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Title: Photographs of Nebulæ and Clusters, Made with the Crossley Reflector

Author: James Edward Keeler

Release date: June 19, 2011 [eBook #36470]

Language: English

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*** START OF THE PROJECT GUTENBERG EBOOK PHOTOGRAPHS OF NEBULÆ AND CLUSTERS, MADE WITH THE CROSSLEY REFLECTOR ***

NOTE.

In the original negatives of subjects 10 and 12, there are faint dark rings immediately surrounding some of the stars in the denser parts of the nebulosity. This effect has no doubt been accentuated in the subsequent photographic processes. On the plates of these two subjects in the completed volume, these rings are very distinct and give rise to a suspicion that the effect has been enhanced by the engraver. A critical examination of the prints seems to confirm this view. In the original proofs these rings were inconspicuous and were not noticed. The processes of steel-facing and printing appear to have increased the effect markedly, as it is much stronger on the sheets printed for the edition than in any of the early proofs.

Inasmuch as these effects were not and could not be discovered until the sheets were assembled in Sacramento for binding, it has not been thought desirable to delay the issue of the volume for several weeks additional in order to have new plates and new prints of these subjects made by the distant engraver.

Lick Observatory,

Mount Hamilton,

November, 1908.

Plate 10

THE GREAT NEBULA IN ORION

UNIVERSITY OF CALIFORNIA PUBLICATIONS

PUBLICATIONS

OF THE

LICK OBSERVATORY

PRINTED BY AUTHORITY OF THE REGENTS OF THE UNIVERSITY

VOLUME VIII

SACRAMENTO

W. W. SHANNON

SUPERINTENDENT OF STATE PRINTING

1908

AS A TRIBUTE TO THE MEMORY OF

JAMES EDWARD KEELER

and in recognition of his great worth as a man and as an astronomer, the plates for this volume have been provided by

MR. WILLIAM ALVORD,

MR. F. M. SMITH,

MR. ROBERT BRUCE,

MISS JENNIE SMITH,

MR. WILLIAM H. CROCKER,

MISS MATILDA H. SMITH,

MRS. WILLIAM H. CROCKER,

MR. BENJAMIN THAW,

MR. E. J. DE SABLA,

MRS. WILLIAM THAW,

MR. J. A. DONOHOE,

MR. ROBERT J. TOBIN,

MRS. PHŒBE A. HEARST,

THE UNIVERSITY OF CALIFORNIA,

MR. JOHN B. JACKSON,

THE STATE OF CALIFORNIA.

MR. E. J. MOLERA,

ORGANIZATION OF THE LICK OBSERVATORY.

HON. CHARLES W. SLACK,

HON. WARREN R. PORTER,

HON. WILLIAM H. CROCKER,

REV. PETER C. YORKE,

Committee of the Regents for the Lick Observatory.

BENJAMIN IDE WHEELER,

President of the University.

W. W. CAMPBELL,

Director and Astronomer.

R. H. TUCKER,*

Astronomer.

C. D. PERRINE,

Astronomer.

H. D. CURTIS,

Mills Acting Astronomer.

R. G. AITKEN,

Astronomer.

W. H. WRIGHT,

Astronomer.

J. H. MOORE,

Assistant Astronomer.

SEBASTIAN ALBRECHT,

Assistant Astronomer.

MISS A. M. HOBE,

Carnegie Assistant.

G. F. PADDOCK,

Mills Assistant.

MISS L. B. ALLEN,

Carnegie Assistant.

E. A. FATH,

Fellow.

J. C. DUNCAN,

Fellow.

MISS A. E. GLANCY,

Fellow.

MISS M. E. FRENCH,*

Secretary.

MISS A. J. VAN COOVER,

Secretary.

* Absent on leave.

PHOTOGRAPHS OF NEBULÆ AND CLUSTERS,

MADE WITH

THE CROSSLEY REFLECTOR,

BY

JAMES EDWARD KEELER,

DIRECTOR OF THE LICK OBSERVATORY.

1898-1900.

PREFACE.

When Professor Keeler entered upon the duties of Director of the Lick Observatory, on June 1, 1898, he planned to devote his observing time for several years to photographing the brighter nebulæ and star clusters, with the Crossley reflector. The story of his wonderful success with this difficult instrument is familiar to all readers of astronomical literature: this form of telescope was in effect born again; and his contributions to our knowledge of the nebulæ were epoch-making.

Professor Keeler’s observing programme included one hundred and four subjects. At the time of his lamented death, on August 12, 1900, satisfactory negatives of two-thirds of the selected objects had been secured. The unphotographed objects were mainly those which come into observing position in the unfavorable winter and spring months. The completion of the programme was entrusted to Assistant Astronomer Perrine. The observers were assisted chiefly by Mr. H. K. Palmer, and in smaller degree by Messrs. Joel Stebbins, C. G. Dall, R. H. Curtiss and Sebastian Albrecht.

Professor Keeler’s photographs enabled him to make two discoveries of prime importance, not to mention several that are scarcely secondary to them.

1st.—“Many thousands of unrecorded nebulæ exist in the sky. A conservative estimate places the number within reach of the Crossley reflector at about 120,000. The number of nebulæ in our catalogues is but a small fraction of this.” [The number already discovered and catalogued did not exceed 13,000. Later observations with the Crossley reflector, with longer exposure-times and more sensitive plates, render it probable that the number of nebulæ discoverable with this powerful instrument is of the order of half a million.]

2d.—“Most of these nebulæ have a spiral structure.”

The photographs of the one hundred and four subjects contain the images of 744 nebulæ not previously observed. A catalogue of these is published in the present volume. Their positions, which are thought to be accurate within 1″, were determined by Messrs. Palmer, Curtiss, and Albrecht.

The main purpose of this volume is to reproduce and make available for study, the larger and more interesting nebulæ and clusters on the programme, sixty-eight in number. The thirty-six subjects not reproduced are for the most part small or apparently not of special interest. The difficulties attending the reproduction of astronomical photographs by mechanical processes are well-known to all who have made the attempt. It seems necessary to recognize, at least at present, that delicate details of structure will be lost, and that contrasts between very bright and very faint regions will be changed, especially if a good sky background is preserved; in other words, that the best obtainable reproductions fall far short of doing justice to the original photographs. Technical studies should be based upon the original negatives or upon copies on glass.

After considerable experimental work, involving several methods and several firms, the making of the heliogravure plates and the hand-press prints was entrusted to The Photogravure and Color Company of New York City. To this firm’s continued interest and willingness to act on constructive criticism is due much of the excellence of the results.

The expensive reproductions could hardly have been undertaken without the generous assistance of the donors mentioned on a preceding page.

Professor Keeler’s description of the Crossley reflector, of his methods of observing, and of the chief results obtained, was written only a short time before his death. It is here republished. Other results of his work are described in the several papers to which the footnotes refer.

TABLE OF CONTENTS.

The Orion Nebula,

Frontispiece

The Crossley Reflector of the Lick Observatory,

Page

11

List of Nebulæ and Clusters Photographed,

"

30

Catalogue of New Nebulæ Discovered on the Negatives,

"

31

Positions of Known Nebulæ Determined from the Crossley Negatives,

"

42

List of Illustrations,

"

45

Illustrations,

following

"

46

THE CROSSLEY REFLECTOR OF THE LICK OBSERVATORY.[1]

By JAMES E. KEELER.

The Crossley reflector, at present the largest instrument of its class in America, was made in 1879 by Dr. A. A. Common, of London, in order to carry out, and test by practical observation, certain ideas of his respecting the design of large reflecting telescopes. For the construction of the instrument embodying these ideas, and for some fine astronomical photographs obtained with it, Dr. Common was awarded the gold medal of the Royal Astronomical Society in 1884.

In 1885, Dr. Common, wishing to make a larger telescope on a somewhat similar plan, sold the instrument to Edward Crossley, Esq., F. R. A. S., of Halifax, England. Mr. Crossley provided the telescope with a dome of the usual form, in place of the sliding roof used by its former owner, and made observations with it for some years; but the climate of Halifax not being suitable for the best use of such a telescope, he consented, at the request of Dr. Holden, then Director of the Lick Observatory, to present it to this institution. The funds for transporting the telescope and dome to California, and setting them up on Mount Hamilton, were subscribed by friends of the Lick Observatory, for the most part citizens of California. The work was completed, and the telescope housed in a suitable observatory building, in 1895.[2]

On taking charge of the Lick Observatory in 1898, I decided to devote my own observing time to the Crossley reflector, although the whole of my previous experience had been with refracting telescopes. I was more particularly desirous of testing the reflector with my own hands, because such preliminary trials of it as had been made had given rise to somewhat conflicting opinions as to its merits.[3] The result of my experience is given in the following article, which is written chiefly with reference to American readers. If I have taken occasion to point out what I regard as defects in the design or construction of the instrument, I have done so, not from any desire to look a gift horse in the mouth, but in the interest of future improvement, and to make intelligible the circumstances under which the work of the reflector is now being done and will be done hereafter. The most important improvements which have suggested themselves have indeed already been made by Dr. Common himself, in constructing his five-foot telescope. The three-foot reflector is, in spite of numerous idiosyncracies which make its management very different from the comparatively simple manipulation of a refractor, by far the most effective instrument in the Observatory for certain classes of astronomical work. Certainly no one has more reason than I to appreciate the great value of Mr. Crossley’s generous gift.

DOME OF THE CROSSLEY REFLECTOR.

The Crossley dome is about 350 yards from the main Observatory, at the end of a long rocky spur which extends from the Observatory summit toward the south, and on which are two of the houses occupied by members of the Observatory staff. It is below the level of the lowest reservoir, “Huyghens,” which receives the discharge from the hydraulic machinery of the 36-inch refractor, and therefore the water engine furnished by Mr. Crossley for turning the dome can not be used, unless a new water system—overflow reservoir, pump and windmill—is provided. In this respect a better site would have been a point on the south slope of “Kepler,”—the middle peak of Mount Hamilton—just above the Huyghens reservoir. No addition to the present water system would then have been needed. The slope of the mountain at this place might cut off the view of the north horizon, but since the telescope can not be turned below the pole, this would be a matter of no consequence. Water-power for the dome is not, however, really necessary.

The cylindrical walls of the dome, 36¼ feet inside diameter, are double, and provided with ventilators. Opening into the dome, on the left of the entrance, are three small rooms, one of which has been fitted up as a photographic dark room, and another, containing a sidereal clock and a telephone, which communicates with the main Observatory, as a study, while the third is used for tools and storage. There is also a small room for the water engine, in case it should be used. The dome is at present supplied with water from only the middle reservoir, Kepler, which is reserved for domestic purposes and is not allowed to pass through the machinery.

The dome itself, 38 feet 9 inches in diameter, is made of sheet-iron plates riveted to iron girders. It also carries the wooden gallery, ladders, and observing platform, which are suspended from it by iron rods. The apparatus for turning the dome consists of a cast-iron circular rack bolted to the lower side of the sole-plate, and a set of gears terminating in a sprocket-wheel, from which hangs an endless rope. As the dome does not turn easily, it has been necessary to multiply the gearing of the mechanism so that one arm’s-length pull on the rope moves the dome only about one inch. In some positions of the telescope the dome can not be moved more than six or eight inches at a time without danger of striking the tube, and this slowness of motion is then not disadvantageous. It is only when the dome has to be moved through a considerable angle, as in turning to a fresh object, or in photographing some object which passes nearly through the zenith, that the need for a mechanical means of rotation is felt.

The observing slit, 6 feet wide, extends considerably beyond the zenith. It is closed by a double shutter, which is operated by an endless rope. The upper part, within the dome, is also closed by a hood, or shield, which serves to protect the telescope from any water that may find its way through the shutter, and which is rolled back to the north when observations are made near the zenith. I have recently fitted the lower half of the slit with a wind-screen, which has proved to be a most useful addition. It is made of tarpaulin, attached to slats which slide between the two main girders, and is raised or lowered by halliards, which belay to cleats on the north rail of the gallery. A more detailed description of the dome has been given in an article by Mr. Crossley,[4] from which the reduced figure in Fig. 1[5] has been taken.

The mounting of the three-foot reflector has been very completely described and illustrated by Dr. Common,[6] so that only a very general description need be given here. The most important feature of the mounting is that the telescope tube, instead of being on one side of the polar axis, as in the usual construction, is central, so that the axis of the mirror and the polar axis are in the same line when the telescope is directed to the pole. The declination axis is short, and is supported by a massive goose-neck bolted to the upper end of the polar axis. The mirror is placed just above the declination axis. Its weight, and the weight of the whole tube and eye-end, are counterpoised by slabs of lead, placed in two iron boxes, between which the goose-neck of the polar axis passes. The great advantage of this arrangement, and the controlling principle of the design, is that the telescope is perfectly free to pass the meridian at all zenith distances. No reversal of the instrument is needed, or is indeed possible.

THE CROSSLEY REFLECTOR.

For long-exposure photography, the advantage above referred to is obvious, but it is attended by certain disadvantages. One of these is that a very much larger dome is required than for the usual form of mounting. Another is the great amount of dead weight which the axes must carry; for the mirror, instead of helping to counterpoise the upper end of the tube, must itself be counterpoised. When anything is attached to the eye-end (and in astrophysical work one is always attaching things to the eye-end of a telescope), from ten to twenty times as much weight must be placed in the counterpoise boxes below the declination axis. Where room is to be found for the weights required to counterpoise the Bruce spectrograph, is a problem which I have not yet succeeded in solving.

In his five-foot reflector, Dr. Common has caused the telescope tube to swing between two large ears, which project from the upper end of the boiler-like polar axis, the pivots constituting the declination axis being near, but above, the lower end of the tube. The mirror, therefore, helps to counterpoise the upper end of the tube. This I regard as a distinct improvement. The danger of large masses of metal near the mirror injuring the definition is, in my opinion, imaginary; at least there is no such danger on Mount Hamilton, where the temperature variations are unusually small. Experience with the Crossley reflector, as well as with the other instruments of the Lick Observatory, shows that the definition depends almost entirely on external conditions.

My first trials of the reflector, as first mounted at the Lick Observatory, showed that the center of motion was inconveniently high. Among other difficulties arising from this circumstance, the spectroscope projected beyond the top of the dome, so that it had to be removed before the shutter could be closed. In July, 1898, the pier was therefore cut down two feet. This brought the eye-end down nearly to the level of the gallery rail, where it was at a convenient height for the observer when sitting on a camp-stool, and it made all parts of the mounting more accessible. Toward the north and south, the range of the telescope, being limited in these directions by the construction of the mounting, was not affected by the change, but the telescope can not now be used at such low altitudes as formerly, near the east and west points of the horizon. The only occasion likely to call for the use of the reflector in these positions is the appearance of a large comet near the Sun, and, after some consideration, I decided to sacrifice these chances for the sake of increasing the general usefulness of the instrument. Except in rare cases, all observations are made within three hours of the meridian.

To adapt the mounting to the latitude of Mount Hamilton, a wedge-shaped casting, shown in the illustration, had been provided, but through some error, arising probably from the fact that the telescope had been used in two different latitudes in England, the angle of the casting was too great. When the pier was cut down its upper surface was therefore sloped toward the south, in order to compensate the error in the casting. Plate VII shows the instrument very nearly as it is at the present time.

The polar axis of the Crossley reflector is a long, hollow cylinder, separated by a space of about one-eighth of an inch from its concentric casing. The idea was to fill this space with mercury, and float the greater part of the thrust of the axis, the function of a small steel pin at the lower end being merely to steady the axis. But this mercury flotation, as applied to the Crossley telescope, is a delusion, as I think Mr. Crossley had already found. The mercury, it is true, relieves the thrust to some extent, but it greatly increases the already enormous side pressure on the steel pin at the bottom, thus creating a much greater evil than the one it is intended to remedy. The workmen who set up the mounting inform me that the small bearing at the lower end of the polar axis is badly worn, as I should expect it to be. Instead of putting mercury into the space intended for it, I have therefore poured in a pint or so of oil, to keep the lower bearing lubricated. For the reasons indicated above, the force required to move the telescope in right ascension is perhaps five times greater than it should be. The lower end of the polar axis ought to be fitted with ball bearings to take the thrust, and with a pair of friction wheels on top; but it would be difficult to make these changes now. It should be observed that the disadvantages of the mercury flotation are considerably greater at Mount Hamilton than at the latitude for which the telescope was designed.

THE CROSSLEY REFLECTOR.

As already stated above, the range of the telescope is limited on the south by the construction of the mounting. The greatest southern declination which can be observed is 25°. In England this would doubtless mark the limit set by atmospheric conditions, but at Mount Hamilton it would be easy to photograph objects 15° farther south, if the telescope could be pointed to them.

The original driving-clock having proved to be inefficient, at least without an electric control, a new and powerful driving-clock was made by the Observatory instrument maker, from designs by Professor Hussey. In its general plan it is like that of the 36-inch refractor. The winding apparatus, contained in the large casting of the original mounting, has no maintaining power, and can not easily be fitted with one. The clock could in no case be wound during a photographic exposure, on account of the tremors attending the operation, but it would be somewhat more convenient to have the stars remain on the plate during the winding. With a little practice, however, one can wind the clock without actually stopping it, though the object must afterwards be brought back to its place by means of the slow motion in right ascension.

Two finders have recently been fitted to the Crossley reflector. One has an object-glass of four inches aperture and eight feet six inches focal length, with a field of about 1° 2′, which is very nearly the photographic field of the main telescope. Its standards are bolted to one of the corner tubes of the reflector. The other finder has a three-inch objective and a large field. It had not been mounted when the photograph for the plate was made.

When a telescope is used for photographing objects near the pole, with long exposures, the polar axis must be quite accurately adjusted, for otherwise the centers of motion of the stars and of the telescope will not agree, and the star images will be distorted. It is true that with a double-slide plate-holder, like the one used with the Crossley reflector, one star—namely, the guiding star—is forced to remain in a fixed position with respect to the plate; but the differential motion of the other stars causes them to describe short arcs, or trails, around this star as a center. A considerable part of the spring of 1899 was spent in efforts to perfect the adjustment of the polar axis, an operation which, on account of the peculiar form of the mounting, offers unusual difficulties.

In the first plan which was tried, the reflector was used as a transit instrument. The inclination of the declination axis was determined with a hanging level which had been provided by Mr. Crossley, the hour circle and polar axis being very firmly clamped. The clock correction being known from the records kept at the Observatory, the collimation and azimuth constants were found by the usual formulæ. This method failed to give satisfactory results, and it was found later that the declination and polar axis were not exactly at right angles.

There is only one part of the sky on which the telescope can be reversed; namely, the pole. A method which promised well, and on which some time was spent, consists in photographing the pole (the declination axis being horizontal) by allowing the stars near it to trail for ten or fifteen minutes, then turning the polar axis 180° and photographing the pole again on the same plate. Half the distance between the images gives the error of the polar axis, which, if the plate is properly oriented, is easily resolved into horizontal and vertical components; while the distance of each image from the center of the plate is this error increased or diminished by twice the deviation of the telescope axis. In this case the vertical component depends upon the reading of the declination circle, and the horizontal component gives the error of collimation. This method failed, however, to give consistent results, mainly on account of instability of the mirror, and was abandoned.

The use of the large mirror for purposes of adjustment was finally given up, and the axis was adjusted by observations of Polaris with the long finder, in the usual manner. In order to reach the star at lower culmination the finder tube had to be thrown out of parallelism with the main telescope.

The base-plate having no definite center of rotation in azimuth, and the wedges and crowbars used for moving it being uncertain in their action, a watch telescope, provided with a micrometer eyepiece, was firmly secured to the mounting throughout these operations, in such manner that a mark on the southern horizon could be observed through one of the windows of the dome. The errors of the polar axis were finally reduced to within the limits of error of observation.

The movable hour circle and driving wheel of the Crossley reflector has two sets of graduations. The driving screw having been thrown out of gear, the circle is turned until the outer vernier indicates the sidereal time, whereupon the driving screw is thrown into gear again. The inner vernier is then set to the right ascension of the object which it is desired to observe. As an inconsistency, of minor importance, in the design of the mounting, I may note that the slow motion in right ascension changes the reading of the outer vernier instead of that of the inner one. In practice, however, no inconvenience is caused by this construction.

In the early experiments and photographic work with the Crossley telescope, irregularities in driving were a source of great annoyance. Dr. Roberts, in laying down the conditions which should be fulfilled by a good photographic telescope, says that a star should remain bisected by a thread in the eyepiece for two minutes at a time. The Crossley telescope was so far from fulfilling this condition that a star would not keep its place for two consecutive seconds; and the greatest alertness on the part of the observer did not suffice to ensure round star images on a photographic plate. It was obvious that the fault did not lie with the driving clock; in fact, many of the sudden jumps in right ascension, if explained in this way, would have required the clock to run backward; nevertheless the clock was tested by causing its revolutions to be recorded on a chronograph at the main Observatory, together with the beats of one of the standard clocks. For this purpose a break-circuit attachment was made by Mr. Palmer. The errors of the clock were in this way found to be quite small.

The principal source of the irregularities was found in the concealed upper differential wheel of the Grubb slow motion. This wheel turned with uncertain friction, sometimes rotating on its axis, and sometimes remaining at rest. After it was checked the driving was much better, and was still farther improved by repairing some defective parts of the train. Small irregularities still remain. They seem to be partly due to inaccuracies in the cutting of the gears, or of the teeth of the large driving wheel, and partly to the springing of the various parts, due to the very considerable friction of the polar axis in its bearings. The remaining irregularities are so small, however, that they are easily corrected by the screws of the sliding plate-holder, and with reasonable attention on the part of the observer, round star images are obtained with exposures of four hours’ duration.

The large mirror, the most important part of the telescope, has an aperture of three feet, and a focal length of 17 feet 6.1 inches. It was made by Mr. Calver. Its figure is excellent. On cutting off the cone of rays from a star, by a knife-edge at the focus, according to the method of Foucault, the illumination of the mirror is very uniform, while the star disks as seen in an ordinary eyepiece are small and almost perfectly round. They are not, I think, quite so good as the images seen with a large refractor; still, they are very good indeed, as the following observations of double stars, made recently for this purpose, will show.

Several close double stars were examined on the night of April 17, 1900, with a power of 620. The seeing was four on a scale of five. The magnitudes and distances of the components, as given in the table, are from recent observations by Professor Hussey with the 36-inch refractor.

Star.

Mag.

d.

Result of Obs.

ΟΣ 208 (φ Urs. Maj.)

5.0, 5.5

0″.35

Not resolved; too bright.

ΟΣ 249, AB

7.2, 8.0

0 .54

Easily resolved.

ΟΣ 250

7.7, 8.0

0 .44

Resolved.

ΟΣ 267

8.0, 8.2

0 .30

Just resolved at best moments.

Although the theoretical limit of resolution for a three-foot aperture is not reached in these observations, I do not think the mirror can do any better.

The small mirror, or flat, at the upper end of the tube, is circular, the diameter being nine inches. Its projection on the plane of the photographic plate is therefore elliptical; but the projection of the mirror and its cell on the plane of the great mirror is very nearly circular.

The small mirror, acting as a central stop, has the effect of diminishing the size of the central disk of the diffraction pattern, at the expense of an increase in the brightness of the system of rings. To this effect may be due, in part, the inferiority of the reflector for resolving bright doubles, as compared with a refractor of the same aperture. For photographic purposes, it is evident that the mirror is practically perfect.

The upper end of the tube can be rotated, carrying with it the flat and the eye-end. Whenever the position is changed, the mirrors have to be re-collimated. In practice it is seldom necessary to touch the adjusting screws of the mirrors themselves. The adjustment is effected by means of clamping and butting screws on the eye-end, and a change of the line of collimation, with respect to the finders and the circles, is avoided. The operation is generally referred to, however, as an adjustment of the mirrors.

For adjusting the mirrors there are two collimators. One of these is of the form devised by Mr. Crossley.[7] It is very convenient in use, and is sufficiently accurate for the adjustment of the eye-end when the telescope is used for photographic purposes, inasmuch as the exact place where the axis of the large mirror cuts the photographic plate is not then a matter of great importance, so long as it is near the center. Moreover, as stated farther below, the direction of the axis changes during a long exposure. The other collimator is of a form originally due, I think, to Dr. Johnstone Stoney. It consists of a small telescope, which fits the draw-tube at the eye-end. In the focus of the eyepiece are, instead of cross-wires, two adjustable terminals, between which an electric spark can be passed, generated by a small induction machine, like a replenisher, held in the observer’s hand. The terminals are at such a distance inside the principal focus of the objective, that the light from the spark, after reflection from the flat, appears to proceed from the center of curvature of the large mirror. The rays are therefore reflected back normally, and form an image of the spark which, when the mirrors are in perfect adjustment, coincides with the spark itself. The precision of this method is very great. It is in fact out of proportion to the degree of refinement attained in other adjustments of the reflector, for a slight pressure of the hand on the draw-tube, or movement of the telescope to a different altitude, instantly destroys the perfection of the adjustment. I have provided these collimators with an adapter which fits the photographic apparatus, so that one can adjust the mirrors without having to remove this apparatus and substitute for it the ordinary eye-end carrying the eyepieces.

For visual observation the Crossley telescope is provided with seven eyepieces, with powers ranging from 620 downward. The lowest power is only 60, and consequently utilizes only 12 inches of the mirror, 9 of which are covered by the central flat. It is therefore of little value, except for finding purposes. The next lowest power utilizes 28 inches of the mirror. The other eyepieces call for no remark.

But, while the Crossley reflector would doubtless be serviceable for various kinds of visual observations, its photographic applications are regarded as having the most importance, and have been chiefly considered in deciding upon the different changes and improvements which have been made.

The interior of the dome is lighted at night by a large lamp, which is enclosed in a suitable box or lantern, fitted with panes of red glass, and mounted on a portable stand. In order to diffuse the light in the lower part of the dome, where most of the assistant’s work is done, the walls are painted bright red; while to prevent reflected light from reaching the photographic plate, the inner surface of the dome itself, the mounting, and the ladders and gallery are painted dead black. The observer is therefore in comparative darkness, and not the slightest fogging of the plate, from the red light below, is produced during a four-hours’ exposure. On the few occasions when orthochromatic plates are used the lamp need not be lighted.

Experiments have shown that the fogging of the photographic plate, during a long exposure, is entirely due to diffuse light from the sky, and is therefore unavoidable. For this reason the cloth curtains which lace to the corners of the telescope tube, enclosing it and shutting out light from the lower part of the dome, have not been used, since their only effect would be to catch the wind and cause vibrations of the telescope. They would probably have little effect on the definition, and at any rate could not be expected to improve it.

For photographing stars and nebulæ the Crossley reflector is provided with a double-slide plate-holder, of the form invented by Dr. Common.[8] This apparatus, which had suffered considerably in transportation, and from general wear and tear, was thoroughly overhauled by the Observatory instrument-maker. The plates were straightened and the slides refitted. A spring was introduced to oppose the right ascension screw and take up the lost motion—the most annoying defect that such a piece of apparatus can have—and various other improvements were made, as the necessity for them became apparent. They are described in detail farther below.

The present appearance of the eye-end is shown in the illustration. The plate-holder is there shown, however, on one side of the tube, and its longer side is parallel to the axis of the telescope. This is not a good position for the eye-end, except for short exposures. In practice, the eye-end is always placed on the north or south side of the tube, according as the object photographed is north or south of the zenith. The right ascension slide is then always at right angles to the telescope axis, and the eye-end can not get into an inaccessible position during a long exposure.

As the original wooden plate-holders were warped, and could not be depended upon to remain in the same position for several hours at a time, they were replaced by new ones of metal, and clamping screws were added, to hold them firmly in place. The heads of these screws are shown in the plate, between the springs which press the plate-holder against its bed.

To illuminate the cross-wires of the guiding eyepiece, a small electric lamp is used, the current for which is brought down from the storage battery at the main Observatory. The coarse wires have been replaced by spider’s webs,[9] and reflectors have been introduced, to illuminate the declination thread. A collimating lens, placed at its principal focal distance from the incandescent filament of the lamp, makes the illumination of the wires nearly independent of their position on the slide, and a piece of red glass, close to the lens, effectually removes all danger of fogging the plate. The light is varied to suit the requirements of observation by rotating the reflector which throws the light in the direction of the eyepiece.

DOUBLE-SLIDE PLATE-HOLDER OF THE CROSSLEY REFLECTOR.

In long exposures it is important for the observer to know at any moment the position of the plate with reference to its central or zero position. For this purpose scales with indexes are attached to both slides; but as they can not be seen in the dark, and, even if illuminated with red light, could not be read without removing the eye from the guiding eyepiece, I have added two short pins, one of which is attached to the lower side of the right ascension slide, and the other to its guide, so that the points coincide when the scale reads zero. These pins can be felt by the fingers, and with a little practice the observer can tell very closely how far the plate is from its central position. It would not be a very difficult matter to improve on this contrivance, say by placing an illuminated scale, capable of independent adjustment, in the field of the eyepiece, but the pins answer every purpose. The declination slide is changed so little that no means for indicating its position are necessary.

In this apparatus, as originally constructed, the cross-wires of the guiding eyepiece were exactly in the plane of the photographic plate. The earlier observations made with the Crossley reflector on Mount Hamilton showed that this is not the best position of the cross-wires. The image of a star in the guiding eyepiece, which, when in the middle of its slide, is nearly three inches from the axis of the mirror, is not round, and its shape varies as the eyepiece is pushed in or drawn out. In the plane of the photographic plate (assumed to be accurately in focus), it is a crescent, with the convex side directed toward the center of the plate. This form of image is not suitable for accurate guiding. Outside this position the image changes to an arrow-head, the point of which is directed toward the axis, and this image can be very accurately bisected by the right ascension thread. As the construction of the apparatus did not allow the plane of the cross-wires to be changed, the wooden bed of the plate-holder was cut down, so as to bring the wires and the plate into the proper relative positions.

After some further experience with the instrument, still another change was made in this adjustment. It was found that the focus often changed very perceptibly during a long exposure, and while the arrow-head image above described was suitable for guiding purposes, its form was not greatly affected by changes of focus. Between the crescent and the arrow-head images there is a transition form, in which two well-defined caustic curves in the aberration pattern intersect at an acute angle. The intersection of these caustics offers an excellent mark for the cross-wires, and is at the same time very sensitive to changes of focus, which cause it to travel up or down in the general pattern. The bed of the plate-holder was therefore raised, by facing it with a brass plate of the proper thickness.

Why the focus of the telescope should change during a long exposure is not quite clear. The change is much too great to be accounted for by expansion and contraction of the rods forming the tube, following changes of temperature, while a simple geometrical construction shows that a drooping of the upper end of the tube, increasing the distance of the plate from the (unreflected) axis of the mirror, can not displace the focus in a direction normal to the plate, if it is assumed that the field is flat. The observed effect is probably due to the fact that the focal surface is not flat, but curved. During a long exposure, the observer keeps the guiding star, and therefore, very approximately, all other stars, in the same positions relatively to the plate; but he has no control over the position of the axis of the mirror, which, by changes of flexure, wanders irregularly over the field. The position of maximum curvature, therefore, also varies, and with it the focus of the guiding star relatively to the cross-wires, where the focal surface is considerably inclined to the field of view. It is certain that the focus does change considerably, whatever the cause may be, and that the best photographic star images are obtained by keeping the focus of the guiding star unchanged during the exposures. This is done by turning the focusing screw of the eye-end.

In making the photographs of nebulæ for which the Crossley telescope is at present regularly employed, it was at first our practice to adjust the driving-clock as accurately as possible to a sidereal rate, and then, when the star had drifted too far from its original position, on account of changes of rate or of flexure, to bring it back by the right-ascension slow motion, the observer either closing the slide of the plate-holder or following the motion of the star as best he could with the right-ascension screw. Lately a more satisfactory method, suggested by Mr. Palmer, has been employed. The slow motion in right ascension is of Grubb’s form,[10] and the telescope has two slightly different rates, according to whether the loose wheel is stopped or allowed to turn freely. The driving-clock is adjusted so that one of these rates is too fast, the other too slow. At the beginning of an exposure the wheel is, say, unclamped, and the guiding star begins to drift very slowly toward the left, the observer following it with the screw of the plate-holder. When it has drifted far enough, as indicated by the pins mentioned farther above, the wheel is clamped. The star then reverses its motion and begins to drift toward the right; and so on throughout the exposure. The advantages of this method over the one previously employed are, that the star never has to be moved by the slow motion of the telescope, and that its general drift is in a known direction, so that its movements can be anticipated by the observer. In this way photographs are obtained, with four hours’ exposure, on which the smallest star disks are almost perfectly round near the center of the plate, and from 2″ to 3″ in diameter.

The star images are practically round over a field at least 1 inch or 16′ in diameter. Farther from the center they become parabolic, but they are quite good over the entire plate, 3¼ by 4¼ inches.

From these statements it will be seen that small irregularities in driving no longer present any difficulties. But certain irregular motions of the image still take place occasionally, and so far it has not been possible entirely to prevent their occurrence.

It was found that the declination clamp (the long slow-motion handle attached to which is shown in the illustration) was not sufficiently powerful to hold the telescope firmly during a long exposure. A screw clamp was therefore added, which forces the toothed-declination sector strongly against an iron block just behind it, thus restoring, I think, the original arrangement of the declination clamp as designed by Dr. Common. This clamp holds the tube very firmly.

The irregularities to which I have referred consist in sudden and unexpected jumps of the image, which always occur some time after the telescope has passed the meridian. These jumps are sometimes quite large—as much as one-sixteenth of an inch or 1. They are due to two causes: flexure of the tube, and sliding of the mirror on its bed. When the jump is due to sudden changes of flexure, the image moves very quickly, and vibrates before it comes to rest in its new position, and at the same time there is often heard a slight ringing sound from the tension rods of the tube. There seems to be no remedy for the sudden motions of this class. The tension rods are set up as tightly as possible without endangering the threads at their ends or buckling the large corner tubes. A round telescope tube, made of spirally-wound steel ribbon riveted at the crossings, would probably be better than the square tube now in use.

Jumps due to shifting of the mirror are characterized by a gentle, gliding motion. They can be remedied, in part, at least, by tightening the copper bands which pass around the circumference of the mirror within its cell. This will be done the next time the mirror is resilvered.

All that the observer can do when a jump occurs is to bring back the image as quickly as possible to the intersection of the cross-wires. If all the stars on the plate are faint, no effect will be produced on the photograph; but stars of the eighth magnitude or brighter will leave short trails. The nebula, if there is one on the plate, will, of course, be unaffected.

Before beginning an exposure the focus is adjusted by means of a high-power positive eyepiece. An old negative, from which the film has been partially scraped, is placed in one of the plate-holders, and the film is brought into the common focus of the eyepiece and the great mirror. The appearance of the guiding star, which varies somewhat with the position of the guiding eyepiece on its slide, is then carefully noted, and is kept constant during the exposure by turning, when necessary, the focusing screw of the eye-end. For preliminary adjustments a ground-glass screen is often convenient. On it all the DM. stars, and even considerably fainter ones, as well as the nebulæ of Herschel’s Class I, are easily visible without a lens.

Plates are backed, not more than a day or two before use, with Carbutt’s “Columbian backing,” which is an excellent preparation for this purpose. During the exposure the observer and assistant exchange places every half hour, thereby greatly relieving the tediousness of the work, though two exposures of four hours each, in one night, have proved to be too fatiguing for general practice. At the end of the first two hours it is necessary to close the slide and wind the clock.

The brightness of the guiding star is a matter of some importance. If the star is too bright, its glare is annoying; if it is too faint, the effort to see it strains the eye, and changes of focus are not easily recognized. A star of the ninth magnitude is about right. In most cases a suitable star can be found without difficulty.

In such an apparatus as that described above, the amount by which the plate may be allowed to depart from its zero position is subject to a limitation which has not, I think, been pointed out, although it is sufficiently obvious when one’s attention has been called to it. It depends upon the fact that the plate necessarily moves as a whole, in a straight line which is tangent to a great circle of the sphere, while the stars move on small circles around the pole. The compensation for drift, when the plate is moved, is therefore exact at the equator only.

Let the guiding star have the declination δ_1, and let a star on the upper edge of the plate (which, when the telescope is north of the zenith, and the eye-end is on the north side of the telescope, will be the southern edge) have the declination δ_2. Then if the guiding star is allowed to drift from its zero position through the distance d, the other star will drift through the distance d (cos δ_2 / cos δ_1). If the guiding star is followed by turning the right-ascension screw, the upper edge of the plate, as well as the guiding eyepiece, will be moved through the distance d. Hence there will be produced an elongation of the upper star, represented by

e = d

(

cos δ_2

— 1

)

cos δ_1

from which

d =

e cos δ_1

.

cos δ_2 - cos δ_1

Now, in the Crossley reflector, the upper edge of the plate and the guiding eyepiece are just about 3⅔ inches, or 1°, apart. If e is given, the above formula serves to determine the maximum range of the slide for different positions of the telescope.

It has been stated farther above that the smallest star disks, on a good photograph, are sometimes not more than 2″ in diameter, or in a linear measure, about 1⁄20 mm. An elongation of this amount is therefore perceptible. There are many nebulæ in high northern declinations, and there are several particularly fine ones in about +70°. If, therefore, we take δ_2 = 70°, δ_1, = 71°, e = 0.05, and substitute these values, we find d = 1.0 mm, which is the greatest permissible range of the plate in photographing these nebulæ. Before I realized the stringency of this requirement, by making the above simple computation, I spoiled several otherwise fine negatives by allowing the plate to get too far from the center, thus producing elongated star images.

There is a corresponding elongation in declination, the amount of which can be determined by an adaptation of the formula for reduction to the meridian, but it is practically insensible.

On account of the short focal length of the three-foot mirror, the photographic resolving power of the telescope is much below its optical resolving power. For this reason the photographic images are less sensitive to conditions affecting the seeing than the visual images. On the finest nights the delicate tracery of bright lines or caustic curves in the guiding star is as clear and distinct as in a printed pattern. When the seeing is only fair these delicate details are lost, and only the general form of the image, with its two principal caustics, is seen. A photograph taken on such a night is not, however, perceptibly inferior to one taken when the seeing is perfect. When, however, the image is so blurred that its general form is barely distinguishable, the photographic star disks are likewise blurred and enlarged, and on such nights photographic work is not attempted.

The foregoing account of the small changes which have been made in the Crossley telescope and its accessories may appear to be unnecessarily detailed, yet these small changes have greatly increased the practical efficiency of the instrument, and, therefore, small as they are, they are important. Particularly with an instrument of this character, the difference between poor and good results lies in the observance of just such small details as I have described.

At present the Crossley reflector is being used for photographing nebulæ, for which purpose it is very effective. Some nebulæ and clusters, like the great nebula in Andromeda and the Pleiades, are too large for its plate (3¼ × 4¼ in.), but the great majority of nebulæ are very much smaller, having a length of only a few minutes of arc, and a large-scale photograph is required to show them satisfactorily. It is particularly important to have the images of the involved stars as small as they can be made.

Many nebulæ of Herschel’s I and II classes are so bright that fairly good photographs can be obtained with exposures of from one to two hours; but the results obtained with full-light action are so superior to these, that longer exposures of three and one half or four hours are always preferred. In some exceptional cases, exposures of only a few minutes are sufficient. The amount of detail shown, even in the case of very small nebulæ, is surprising. It is an interesting fact that these photographs confirm (in some cases for the first time) many of the visual observations made with the six-foot reflector of the Earl of Rosse.

Incidentally, in making these photographs, great numbers of new nebulæ have been discovered. The largest number that I have found on any one plate is thirty-one. Eight or ten is not an uncommon number, and few photographs have been obtained which do not reveal the existence of three or four. A catalogue of these new objects will be published in due time.

Some of the results obtained with the Crossley reflector, relating chiefly to particular objects of some special interest, have already been published.[11] The photographs have also permitted some wider conclusions to be drawn, which are constantly receiving further confirmation as the work progresses. They may be briefly summarized as follows:

1. Many thousands of unrecorded nebulæ exist in the sky. A conservative estimate places the number within reach of the Crossley reflector at about 120,000. The number of nebulæ in our catalogues is but a small fraction of this.

2. These nebulæ exhibit all gradations of apparent size, from the great nebula in Andromeda down to an object which is hardly distinguishable from a faint star disk.

3. Most of these nebulæ have a spiral structure.

To these conclusions I may add another, of more restricted significance, though the evidence in favor of it is not yet complete. Among the objects which have been photographed with the Crossley telescope are most of the “double” nebulæ figured in Sir John Herschel’s catalogue (Phil. Trans., 1833, Plate XV). The actual nebulæ, as photographed, have almost no resemblance to the figures. They are, in fact, spirals, sometimes of very beautiful and complex structure; and, in any one of the nebulæ, the secondary nucleus of Herschel’s figure is either a part of the spiral approaching the main nucleus in brightness, or it can not be identified with any real part of the object. The significance of this somewhat destructive conclusion lies in the fact that these figures of Herschel have sometimes been regarded as furnishing analogies for the figures which Poincaré had deduced, from theoretical considerations, as being among the possible forms assumed by a rotating fluid mass; in other words, they have been regarded as illustrating an early stage in the development of double star systems. The actual conditions of motion in these particular nebulæ, as indicated by the photographs, are obviously very much more complicated than those considered in the theoretical discussion.

While I must leave to others an estimate of the importance of these conclusions, it seems to me that they have a very direct bearing on many, if not all, questions concerning the cosmogony. If, for example, the spiral is the form normally assumed by a contracting nebulous mass, the idea at once suggests itself that the solar system has been evolved from a spiral nebula, while the photographs show that the spiral nebula is not, as a rule, characterized by the simplicity attributed to the contracting mass in the nebular hypothesis. This is a question which has already been taken up by Professor Chamberlin and Mr. Moulton of the University of Chicago.

The Crossley reflector promises to be useful in a number of fields which are fairly well defined. It is clearly unsuitable for photographing the Moon and planets, and for star charting. On the other hand, it has proved to be of value for finding and photographically observing asteroids whose positions are already approximately known.

One of the most fruitful fields for this instrument is undoubtedly stellar spectroscopy. Little has been done in this field, as yet, with the Crossley reflector, but two spectrographs, with which systematic investigations will be made, have nearly been completed by the Observatory instrument-maker. One of these, constructed with the aid of a fund given by the late Miss C. W. Bruce, has a train of three 60° prisms and one 30° prism, and an aperture of two inches; the other, which has a single quartz prism, will, I have reason to expect, give measurable, though small, spectra of stars nearly at the limit of vision of the telescope.

The photogravure[12] of the Trifid nebula, which accompanies this article, was made from a photograph taken with the Crossley reflector on July 6, 1899, with an exposure of three hours. It was not selected as a specimen of the work of the instrument, for the negative was made in the early stages of the experiments that I have described, and the star images are not good, but rather on account of the interest of the subject. At the time the photogravures were ordered no large scale photograph of the Trifid nebula had, so far as I am aware, ever been published.[13] The remarkable branching structure of the nebula is fairly well shown in the photogravure, though less distinctly than in the transparency from which it was made. The enlargement, as compared with the original negative, is 2.9 diameters (1 mm = 13″). The fainter parts of the nebula would be shown more satisfactorily by a longer exposure.

LIST OF NEBULÆ AND CLUSTERS PHOTOGRAPHED.

N.G.C. No.

α 1900.0

δ 1900.0

Remarks.

h

m

s

°

′

185

0

33

25

+47

47.3

H II, 707

205

0

34

56

+41

8.2

H V, 18

221

0

37

15

+40

19.0

M 32

224

0

37

17

+40

43.4

Great nebula in Andromeda

247

0

42

3

-21

17.9

H V, 20

253

0

42

36

-25

50.6

H V, I

524

1

19

33

+ 9

1.0

H I, 151

598

1

28

12

+30

8.6

M 33

628

1

31

19

+15

16

M 74

650

1

36

0

+51

4.0

M 76

891

2

16

15

+41

53.6

H V, 19

1023

2

34

8

+38

38.0

H I, 156

1068

2

37

34

-  0

26.3

M 77

1084

2

41

5

-  8

0.0

H I, 64

...

3

41

+24

Pleiades in Taurus

1555

4

16

8

+19

17

T Tauri   and Hind’s variable nebula

1931

5

24

48

+34

10.1

H I, 261

1952

5

28

30

+21

57

Crab nebula in Taurus

...

5

30

-  5

Great nebula in Orion

1977

5

30

27

-  4

54.2

H V, 30

2024

5

36

48

-  1

54.3

H V, 28

2068

5

41

37

+ 0

0.8

M 78

2239

6

25

37

+ 5

1.1

Cluster and nebula in Monoceros

2264

6

35

+10

0

Nebula near 15 Monocerotis

2287

6

42

43

-20

38.4

M 14

...

6

59

40

-10

18.2

New nebula in Monoceros

2359

7

12

54

-13

2.0

H V, 21

2366

7

18

18

+69

13.4

H III, 748

2371-2

7

19

6

+29

41.0

H II, 316-7

2403

7

27

9

+65

48.9

H V, 44

2437

7

35

24

-14

35.3

Cluster and nebula M 46

2632

8

34

+20

Præsepe   cluster

2683

8

46

29

+33

47.8

H I, 200

2841

9

15

6

+51

24

H I, 205

2903-05

9

26

31

+21

57

H I, 56-57

3003

9

42

38

+33

52.8

H V, 26

3031

9

47

18

+69

32

M 81

3079

9

55

9

+56

10.1

H V, 47

3115

10

0

16

-  7

14.0

H I, 163

3169

10

9

4

+ 3

57.7

H I, 4

3184

10

12

15

+41

55.1

H I, 168

3198

10

13

42

+46

3.7

H I, 199

3226-7

10

17

59

+20

24.1

H II, 28-29

3242

10

19

29

-18

5

H IV, 27

...

10

21

7

+68

58

New nebula in Ursa Major   (Coddington).

3556

11

5

40

+56

13.0

H V, 46

3587

11

9

0

+55

33.7

Owl nebula, M 97

3623

11

13

43

+13

38.4

M 65

3627

11

15

1

+13

32

M 66

3726

11

27

56

+47

35.8

H II, 730

4244

12

12

29

+38

22.0

H V, 41

4254

12

13

45

+14

59

M 99

4258

12

14

2

+47

51.6

H V, 43

4303

12

16

18

+ 5

1.7

M 61

4321

12

17

52

+16

22.7

M 100

4382

12

20

21

+18

44.7

M 85

4485-90

12

25

40

+42

15.3

H I, 197-198

4501

12

26

56

+14

58.5

M 88

4536

12

29

20

+ 2

44.2

H V, 2

4559

12

30

59

+28

30.6

H I, 92

4565

12

31

24

+26

32.2

H V, 24

4631

12

37

19

+33

5.9

H V, 42

4656-57

12

39

6

+32

42.8

H I, 176-7

4725

12

45

33

+26

3

H I, 84

4736

12

46

13

+41

39.5

M 94

4826

12

51

49

+22

13.9

M 64

5055

13

11

20

+42

33.6

M 63

5194-5

13

25

39

+47

42.6

M 51

5247

13

32

39

-17

22.4

H II, 297

5272

13

37

35

+28

53

M 3

5457-8

13

59

39

+54

50

M 101

5857-9

15

2

55

+19

58.9

H II, 751-2

5866

15

3

45

+56

9.0

H I, 215

5904

15

13

29

+ 2

27

M 5

6205

16

38

6

+36

39.0

M 13

6218

16

42

2

-  1

46.2

M 12

6412

17

32

41

+75

47.3

H VI, 41

6514

17

55

43

-23

2

Trifid nebula in Sagittarius

6523

17

57

43

-24

23

M 8

6543

17

58

35

+66

38

H IV, 37

6618

18

15

0

-16

13

M 17 Omega nebula

6656

18

30

17

-23

59.3

M 22

6705

18

45

42

-  6

23.3

M 11

6720

18

49

53

+32

54.0

M 57

6853

19

55

17

+22

27

Dumb-Bell nebula

6894

20

12

22

+30

15.5

H IV, 13

6946

20

32

48

+59

48.0

H IV, 76

6951

20

35

47

+65

45.4

6995

20

53

0

+30

49.8

7008

20

57

38

+54

9.5

H I, 192

7009

20

58

11

-11

48

H IV, 1

7023

21

0

30

+67

46.2

H IV, 74

7078

21

25

9

+11

43.7

M 15

7089

21

28

19

-  1

16.0

M 2

7099

21

34

42

-23

38.0

M 30

7217

22

3

24

+30

52.3

H II, 207

7331

22

32

30

+33

53.9

H I, 53

7448

22

55

7

+15

26.6

H II, 251

7479

22

59

56

+11

47.0

H I, 55

7537-41

23

9

38

+ 3

59.4

H II, 429-30

7662

23

21

5

+41

59.2

H IV, 18

7782

23

48

47

+ 7

24.8

H III, 233

7814

23

58

8

+15

34.5

H II, 240

7817

23

58

52

+20

11.6

H II, 227

CATALOGUE OF NEW NEBULÆ DISCOVERED ON THE NEGATIVES.

No.

α 1900.0

Precession.

δ 1900.0

Precession.

Description.

h

m

s

s

°

′

″

″

1

0

0

27.4

+3.0732

+20

34

57

+20.048

vS eeF

2

0

32

7.7

3.2795

+47

55

29

19.855

eF N

3

0

32

8.1

3.2801

+48

1

22

19.855

F vbM E140°

4

0

32

9.3

3.2776

+47

37

24

19.855

eF bM

5

0

32

28.8

3.2799

+47

39

5

19.851

B vE70°

6

0

33

23.9

3.2674

+47

55

5

19.841

eF vS

7

0

35

43.1

3.3009

+47

46

18

19.810

eF vS

8

0

40

51.1

2.9793

-21

25

48

19.730

18 vS R

9

0

47

0.1

2.9804

-21

9

17

19.727

16 vS bM 3 sep. parts

10

0

41

16.2

2.9781

-21

29

43

19.723

18 vS R bM

11

0

41

16.7

2.9792

-21

15

2

19.723

18 vS R

12

0

41

29.7

2.9798

-21

3

8

19.719

18 vS bM E50°

13

0

42

4.4

2.9633

-26

0

7

19.711

17 vS R bsw

14

0

42

30.7

2.9780

-20

56

38

19.703

18 vS bM E115°

15

0

42

34.2

2.9620

-25

59

10

19.702

17 vS N E160°

16

0

42

37.6

2.9776

-20

58

28

19.701

14 S E stell N

17

0

42

39.7

2.9772

-21

1

54

19.701

17 vS Spiral bM

18

0

42

39.9

2.9774

-21

0

3

19.700

18 vS Ring?

19

0

42

40.5

2.9770

-21

3

55

19.700

15 S Spiral N bM

20

0

42

40.6

2.9762

-21

13

54

19.700

18 vS R

21

0

43

10.4

2.9603

-25

59

36

19.692

18 vS R bM

22

0

43

16.2

2.9730

-21

37

17

19.691

18 vS dif

23

0

43

27.1

2.9613

-25

40

21

19.688

17 vS R N

24

0

43

29.0

2.9593

-26

0

57

19.687

18 vS R gbM

25

0

44

10.8

2.9714

-21

30

29

19.676

18 vS R

26

0

44

26.6

2.9735

-20

58

35

19.672

17 vS R bM

27

1

18

30.9

3.1475

+ 9

27

25

18.887

F S N

28

1

18

53.5

3.1475

+ 9

24

28

18.875

F vbM Spiral?

29

1

19

11.3

3.1474

+ 9

21

53

18.867

F vbM Spiral?

30

1

19

30.7

3.1467

+ 9

14

18

18.857

F bM E

31

1

29

50.7

3.2101

+15

6

37

18.526

pF E45° bp

32

1

29

54.4

3.2161

+15

43

25

18.524

F R

33

1

30

20.9

3.2127

+15

17

38

18.509

vF L R

34

1

30

24.7

3.2132

+15

20

28

18.507

pF S vF extension 135°

35

1

30

35.9

3.2153

+15

32

2

18.501

S pB pmb M

36

1

30

54.7

3.2176

+15

43

1

18.491

vvF vS

37

1

31

5.0

3.2179

+15

43

38

18.485

F S E95°

38

1

31

15.9

3.2159

+15

30

44

18.478

pF S R

39

1

31

25.7

3.2187

+15

44

34

18.473

vF S R

40

1

31

44.8

3.2194

+15

46

49

18.462

F L R gbM

41

1

31

44.8

3.2126

+15

4

18

18.462

F L gbM R

42

1

32

5.9

3.2158

+15

20

54

18.450

S pB E135°

43

1

32

41.3

3.2171

+15

23

22

18.430

vF S E45°

44

1

32

48.8

3.2156

+15

12

27

18.424

vF pL

45

1

33

10.4

3.2168

+15

16

49

18.413

vF pL gbM

46

1

33

13.2

3.2166

+15

15

14

18.412

p B R gbM

47

2

14

10.2

3.7341

+41

50

8

16.715

pF E135°

48

2

14

26.6

3.7349

+41

49

1

16.701

pB N R

49

2

14

33.9

3.7307

+41

37

31

16.696

B N

50

2

14

36.7

3.7313

+41

38

24

16.694

F

51

2

14

55.0

3.7506

+42

24

20

16.677

eF vS bM E135°

52

2

15

6.2

3.7517

+42

25

6

16.668

F gbM E130° Spiral?

53

2

15

14.9

3.7493

+42

16

44

16.661

F pmbM

54

2

15

16.1

3.7484

+42

14

4

16.659

F B*  f

55

2

15

38.4

3.7666

+42

55

0

16.641

eF vS R

56

2

15

43.8

3.7503

+42

13

58

16.637

S F R

57

2

15

56.5

3.7724

+43

5

24

16.626

F E170° bsf

58

2

16

1.0

3.7539

+42

20

55

16.623

B S vbM E150° bnp

59

2

16

6.4

3.7403

+41

44

51

16.619

S F R

60

2

16

9.7

3.7408

+41

45

26

16.616

F S pmbM

61

2

16

13.0

3.7613

+42

36

32

16.613

pB vbM E150° Spiral?

62

2

16

31.1

3.7640

+42

39

27

16.598

eeF E50°

63

2

16

34.5

3.7412

+41

42

6

16.595

pB pmbM

64

2

16

40.3

3.7620

+42

33

22

16.591

B S pbM

65

2

16

43.3

3.7403

+41

38

14

16.588

pB E0° pmbM

66

2

16

53.2

3.7625

+42

32

12

16.580

vB S mbM

67

2

16

57.8

3.7567

+42

16

48

16.576

F triN npN

68

2

17

13.8

+3.7403

+42

22

37

+16.563

pB bs B*  p

No.

α 1900.0

Precession.

δ 1900.0

Precession.

Description.

h

m

s

s

°

′

″

″

69

2

17

18.9

+3.7661

+42

36

12

+16.559

pS pB gbM E40°

70

2

17

28.5

3.7415

+41

33

3

16.551

pF S R

71

2

17

28.8

3.7560

+42

9

35

16.551

vF

72

2

17

33.2

3.7606

+42

20

17

16.547

F vS bnp

73

2

17

36.2

3.7789

+43

3

25

16.545

eeF S

74

2

17

37.2

3.7469

+41

45

2

16.544

F vL vmbM

75

2

17

41.8

3.7592

+42

15

8

16.540

S pB bs

76

2

17

43.3

3.7554

+42

5

21

16.539

F bsp

77

2

17

44.6

3.7441

+42

18

28

16.538

B S E90° bM

78

2

17

45.5

3.7425

+42

22

45

16.537

F L bM N B*  np

79

2

17

50.8

3.7743

+42

50

20

16.533

pB gbM E135°

80

2

17

51.1

3.7484

+41

46

22

16.532

pB E135° gbM

81

2

18

0.2

3.7743

+42

48

30

16.525

vF pL gbM E50°

82

2

18

0.8

3.7502

+41

48

55

16.525

pF L

83

2

18

4.2

3.7603

+42

14

0

16.522

S B vbM

84

2

18

14.8

3.7579

+42

7

27

16.513

pB E150° Spiral

85

2

18

23.6

3.7792

+42

56

10

16.507

eeF pL E120°

86

2

18

26.7

3.7604

+42

10

8

16.503

vB E45°

87

2

18

30.7

3.7465

+41

34

13

16.499

F E150° bnf

88

2

18

33.5

3.7784

+42

52

19

16.498

B S gbM

89

2

18

34.0

3.7628

+42

14

44

16.497

vS vF bsp

90

2

18

37.4

3.7837

+43

4

26

16.495

S F bs

91

2

31

51.3

3.7209

+38

16

30

15.806

vF vS

92

2

33

53.9

3.7295

+38

19

27

15.694

F vS N

93

2

33

56.7

3.7461

+38

49

15

15.691

F S bn E0° long N

94

2

34

7.5

3.7405

+38

43

4

15.681

pF S i triN

95

2

34

9.2

3.7399

+38

43

10

15.680

pF vS

96

2

34

11.8

3.7259

+38

7

39

15.678

F L E40° Spiral on edge

97

2

34

44.2

3.7402

+38

38

27

15.648

eeeF doubtful

98

2

34

44.4

3.7488

+38

16

16

15.648

pB N E50° S pmbM

99

2

35

1.0

3.7469

+38

18

45

15.632

L F pmbM

100

2

36

32.9

3.7436

+38

30

26

15.548

S F E100°

101

2

36

53.3

3.0662

-  0

24

48

15.525

vS vF gbM

102

2

37

6.0

3.0728

-  0

2

43

15.518

vS F m E30°

103

2

38

44.2

3.0688

-  0

16

20

15.427

F S m E80°

104

2

41

11.6

2.9503

-  8

3

17

15.294

pB vS E135°

105

2

41

53.7

2.9564

-  7

38

9

15.254

vF vS mbM

106

2

42

18.9

2.9499

-  8

2

27

15.230

eeF S

107

4

35

22.9

3.0244

-  2

12

20

7.235

16 S E165° Dif bM

108

4

36

0.6

3.0307

-  1

54

37

7.183

18 vS R

109

4

36

3.6

3.0300

-  1

56

42

7.179

17 vS R stell

110

4

36

12.7

3.0337

-  1

46

19

7.167

16 vS nearly R bM

111

4

36

15.2

3.0238

-  2

13

38

7.164

18 vS R (Spiral?)

112

4

36

40.5

3.0251

-  2

9

53

7.129

18 vS R N

113

4

36

41.2

3.0293

-  1

58

23

7.128

18 vS E30° bn

114

4

37

2.4

3.0268

-  2

5

10

7.099

18 vS dif

115

4

37

26.8

3.0298

-  1

56

51

7.066

15 vS Spiral B N (stell)

116

5

24

48.1

3.9674

+34

6

28

+ 3.075

bright stell N on north side

117

7

14

0.7

6.4903

+69

39

20

- 6.362

17 vS bM

118

7

14

24.5

6.4656

+69

31

49

6.395

17 vS N Ring

119

7

14

37.5

6.4241

+69

18

15

6.413

17 R bM

120

7

15

45.6

6.4282

+69

21

35

6.507

17 vS

121

7

15

50.7

6.4875

+69

41

26

6.514

16 vS R

122

7

16

4.1

6.4719

+69

36

40

6.532

17 vS E125° D?

123

7

16

8.0

6.4219

+69

20

4

6.538

18 vS E70°

124

7

16

35.2

6.4099

+69

16

46

6.575

16 vS iF

125

7

16

48.0

6.4578

+69

33

16

6.593

17 vS R

126

7

17

9.1

6.4119

+69

18

25

6.622

18 vS R

127

7

17

38.5

6.4906

+69

45

29

6.662

17 vS bM R

128

7

17

45.3

6.4750

+69

40

36

6.672

17 vS R bM

129

7

17

49.6

3.7911

+29

41

49

6.677

18 vS F*  inv dif

130

7

17

49.7

6.4843

+69

43

46

6.678

17 vS E135° bM N Spiral

131

7

18

11.1

6.4754

+69

41

28

6.707

16 vS dif 2 or 3 N

132

7

18

14.4

3.7838

+29

27

41

6.711

18 vS iF N

133

7

18

20.1

3.7840

+29

28

20

6.719

18 vS bM

134

7

18

21.1

3.7950

+29

51

18

6.721

18 vS bM

135

7

18

42.2

3.7832

+29

27

23

6.749

18 vS iF sc

136

7

18

51.0

6.6430

+69

38

32

6.763

17 vS E80° bM N Spiral on edge

137

7

18

56.5

3.7827

+29

27

7

6.769

19 vS

138

7

19

10.0

+3.7819

+29

26

7

- 6.788

18 vS R bM N Spiral?

No.

α 1900.0

Precession.

δ 1900.0

Precession.

Description.

h

m

s

s

°

′

″

″

139

7

19

11.6

+3.7800

+29

22

12

- 6.790

18 vS bM

140

7

19

11.8

6.4683

+69

40

54

6.790

15 vS Neb*

141

7

19

25.2

6.4609

+69

38

50

6.809

16 vS R bM N Spiral?

142

7

19

30.0

3.7874

+29

38

22

6.816

18 vS 2N R

143

7

19

34.0

6.4629

+69

39

46

6.821

17 vS R

144

7

19

46.5

3.7859

+29

35

58

6.839

18 vS bM N R

145

7

19

48.3

3.7866

+29

37

21

6.841

18 vS R bM

146

7

21

13.4

6.4694

+69

44

51

6.957

17 vS R bM N Spiral?

147

7

21

57.9

6.4648

+69

44

42

7.018

17 vS bM N R Spiral?

148

7

24

8.0

5.8308

+65

39

28

7.198

pB E200° bn

149

7

30

37.2

5.8297

+65

53

16

7.720

vF vS

150

7

31

10.9

5.8139

+65

47

0

7.767

pB S gpmbM

151

8

32

38.8

3.4536

+19

56

37

12.387

16 S E10° stell N M (Spiral on edge?)

152

8

32

40.2

3.4534

+19

56

0

12.388

17 E95° S dif

153

8

34

11.6

3.4527

+19

59

50

12.493

s17 vS E30° stell N Spiral?

154

8

35

28.9

3.4520

+20

2

47

12.581

17 S Spiral N

155

8

36

7.4

3.4514

+20

3

33

12.624

17 S R bM N

156

8

44

40.5

3.7549

+34

13

21

13.203

eF E140°

157

8

46

1.9

3.7442

+33

50

57

13.290

vF vS

158

8

46

26.8

3.7403

+33

44

26

13.318

F vS N E120° Spiral

159

8

46

52.6

3.7397

+33

45

19

13.345

pB eS N R

160

8

47

20.6

3.7507

+34

14

43

13.376

eF eS bf

161

8

47

56.9

3.7509

+34

18

41

13.415

eeF

162

9

12

0.0

4.2083

+51

47

20

14.898

L 12 m E135°

163

9

12

2.1

4.2062

+51

44

32

14.904

16 E80° bs S

164

9

12

12.5

4.2001

+51

36

54

14.910

17 vS Ring bs

165

9

12

38.0

4.1950

+51

31

43

14.939

16 E155° gbm

166

9

12

40.4

4.1862

+51

18

0

14.936

16 vS E15° stell N

167

9

12

45.4

4.1835

+51

16

34

14.942

16 E75° vbN Spiral?

168

9

13

54.3

4.1814

+51

22

45

15.009

18 vS N bM

169

9

14

0.5

4.1839

+51

26

53

15.016

18 vS scNuclei

170

9

15

23.9

4.1662

+51

11

46

15.091

17 vS R

171

9

15

24.6

4.1652

+51

10

12

15.091

17 vS bN Ring or Spiral

172

9

15

29.3

4.1658

+51

11

59

15.096

17 S R

173

9

15

44.6

4.1631

+51

11

26

15.111

15 B bM E145°

174

9

16

6.3

4.1821

+51

42

11

15.136

17 R S

175

9

16

14.6

4.1638

+51

15

42

15.142

17 L vF bM

176

9

16

31.6

4.1528

+51

46

32

15.168

17 R S bs

177

9

24

20.2

3.4095

+21

49

50

15.597

vF vS

178

9

24

36.8

3.4084

+21

48

6

15.612

pB bs S

179

9

25

58.5

3.4047

+21

45

25

15.687

eF E85°

180

9

26

22.5

3.4046

+21

48

50

15.711

pB S R gpmbM N

181

9

28

0.2

3.4020

+21

52

36

15.801

eeF vS

182

9

41

3.6

3.5855

+33

58

24

16.474

16 vS bM E75°

183

9

41

9.9

3.5850

+33

58

12

16.480

15 vS sbM Spiral

184

9

42

9.0

3.5779

+33

45

49

16.528

17 vS N Spiral?

185

9

42

49.5

3.5822

+34

6

11

16.561

16 vS bM

186

9

43

12.4

3.5805

+34

4

43

16.580

15 vS sbM N Spiral

187

9

43

29.2

3.5789

+34

2

26

16.594

16 vS bnw R

188

9

44

13.0

3.5764

+34

2

7

16.630

14 vS bM N Spiral

189

9

44

24.6

3.5760

+34

3

1

16.640

16 vS R N Spiral?

190

9

44

44.4

3.5668

+33

37

27

16.656

17 vS E20°

191

9

44

52.8

5.0574

+69

28

13

16.670

pB vS R gpmbM

192

9

47

5.7

4.9895

+69

5

27

16.776

pF S bf E90°

193

9

47

22.2

4.9858

+69

5

25

16.790

vF dif

194

9

50

19.4

4.9915

+69

30

40

16.930

pF S E120°

195

9

50

52.8

4.9930

+69

35

26

16.955

eeF S E120°

196

9

50

59.1

5.0068

+69

44

0

16.959

pB S E50° pmbM Spiral

197

9

52

29.2

4.9219

+69

6

51

17.039

eF E100°

198

9

54

4.1

4.1109

+56

5

53

17.096

11 vS neb*

199

9

54

24.7

4.1167

+56

18

38

17.111

18 vS R

200

9

54

26.5

4.1121

+56

11

53

17.113

15 vS E95° bM

201

9

55

14.0

4.1162

+56

27

13

17.148

17 vS R

202

9

56

46.2

4.0872

+56

0

18

17.219

17 vS R bM

203

9

57

29.5

4.0952

+56

20

33

17.250

15 vS R N

204

10

0

15.3

2.9839

-  7

33

34

17.372

17 vS sbN Spiral

205

10

0

40.4

2.9909

-  6

59

25

17.391

17 vS stell sbN

206

1

0

42.8

2.9850

-  7

29

50

17.392

11 S D iF gbN bn

207

10

1

49.7

2.9891

-  7

12

11

17.441

17 vS stell

208

10

6

50.1

+3.1101

+ 3

50

57

-17.653

14 vS D neb*

No.

α 1900.0

Precession.

δ 1900.0

Precession.

Description.

h

m

s

s

°

′

″

″

209

10

7

18.1

+3.1112

+ 4

5

30

-17.671

16 vS iF bM

210

10

7

18.5

3.1112

+ 4

4

25

17.672

16 vS bM N Spiral E50°

211

10

7

58.4

3.1128

+ 3

58

44

17.699

16 vS sbM N Spiral E20°

212

10

8

20.6

3.1137

+ 3

52

13

17.714

15 S iF bM

213

10

9

40.7

3.1169

+ 4

8

34

17.769

18 vS R

214

10

9

44.8

3.1171

+ 4

9

47

17.772

17 vS sbM N Spiral? E45°

215

10

9

48.3

3.6290

+42

0

20

17.776

16 E95° 33″ long small spur follows E45°

216

10

9

50.2

3.1172

+ 4

10

50

17.776

17 vS bM N R

217

10

9

58.9

3.6294

+42

4

6

17.783

17 vS R

218

10

10

3.0

3.6318

+42

12

15

17.786

17 vvS stell

219

10

10

15.5

3.6205

+41

39

52

17.793

15 S E60°

220

10

10

16.8

3.6317

+42

15

56

17.795

vS R stell

221

10

10

16.8

3.6311

+42

14

7

17.795

18 vvS sbN Spiral?

222

10

10

21.8

3.1184

+ 3

51

52

17.797

17 vS bM N Spiral

223

10

10

23.0

3.6194

+41

38

24

17.798

16 vS bM Spiral N

224

10

10

23.9

3.6208

+41

42

47

17.799

18 vvS R Spiral? N

225

10

10

24.5

3.6206

+41

42

41

17.800

18 vvS sbN iF

226

10

10

50.9

3.6230

+41

56

45

17.817

18 vvS iF

227

10

10

54.4

3.6245

+42

2

23

17.819

17 vS iF

228

10

11

44.0

3.6222

+42

7

31

17.852

18 vvS bn iF

229

10

11

44.0

3.6221

+42

7

3

17.852

18 vvS Spiral sbN

230

10

11

47.5

3.6210

+42

4

27

17.854

17 vS sbN Spiral

231

10

11

52.1

3.6945

+45

40

52

17.856

F S R gbM bf

232

10

11

52.2

3.6214

+42

6

56

17.857

18 vvS iF stell

233

10

12

6.2

3.6114

+41

36

50

17.861

10 S neb*

234

10

12

21.8

3.6231

+42

19

55

17.878

17 vS sbN Spiral

235

10

12

29.1

3.6192

+42

8

54

17.882

17 vS sbN Spiral

236

10

12

31.5

3.6204

+42

13

16

17.883

16 vS stell

237

10

12

33.4

3.6184

+42

7

46

17.884

18 vS E100° Spiral?

238

10

12

41.5

3.6939

+45

51

34

17.890

eeeF??

239

10

12

43.2

3.6150

+41

59

8

17.891

17 vS sbM N

240

10

12

43.5

3.6168

+42

5

16

17.891

16 vvS bN stell

241

10

12

48.1

3.6940

+45

53

41

17.894

F vS R gbM

242

10

12

50.6

3.6940

+45

54

11

17.896

F S E90°

243

10

12

51.3

3.6163

+42

5

23

17.897

18 vvS R stell

244

10

12

57.8

3.6136

+41

58

39

17.901

18 vvS iF

245

10

13

0.4

3.6212

+42

23

5

17.902

16 vS iB N Spiral E30°

246

10

13

4.1

3.6999

+46

14

17

17.905

B S E130° Spiral on edge

247

10

13

10.1

3.7010

+46

18

50

17.909

B R vm bM

248

10

13

19.7

3.6960

+46

7

15

17.915

eF S R bM

249

10

13

33.8

3.6170

+42

17

28

17.924

18 vS stell

250

10

13

37.1

3.6054

+41

42

39

17.927

17 vS Spiral stell N

251

10

13

44.2

3.6159

+42

16

17

17.929

17 vS R gbN

252

10

13

46.0

3.6110

+42

1

15

17.933

17 vvS gbN Spiral N

253

10

13

48.5

3.6972

+46

17

57

17.934

F S E170° Spiral?

254

10

13

53.9

3.6036

+41

41

1

17.938

18 vS sbN

255

10

13

54.5

3.6107

+42

3

31

17.938

17 vS R gbN

256

10

13

57.9

3.6103

+42

3

5

17.940

17 vS iF gbN

257

10

14

0.0

3.6032

+41

41

9

17.942

18 vvS iF

258

10

14

5.5

3.6812

+45

37

1

17.944

vF vvS R

259

10

14

11.5

3.6113

+42

9

10

17.949

18 vvS bN Spiral

260

10

14

12.5

3.6113

+42

9

44

17.949

17 vS sbN Spiral

261

10

14

24.2

3.6104

-42

9

42

17.958

19 vvS iF E130°

262

10

14

26.8

3.6865

+45

57

27

17.958

B S E45°

263

10

14

33.0

3.6785

+45

36

39

27.962

vF vS E100°

264

10

14

35.7

3.6250

+42

0

31

17.965

17 vS Spiral N E100°

265

10

14

46.3

3.6916

+46

16

40

17.972

vvF E100° spindle shaped

266

10

14

52.3

3.6779

+45

39

59

17.975

vF S R

267

10

15

22.5

3.6866

+46

11

40

17.995

F R S gbM

268

10

16

17.4

3.6765

+45

57

9

18.031

F S R gbM

269

10

16

27.1

4.5844

+68

53

10

18.038

S pB bf

270

10

16

37.1

3.6761

+46

1

1

18.044

F pmbM E10°

271

10

17

8.0

3.2872

+20

19

46

18.062

13 vS sbM N Spiral E135°

272

10

17

12.7

3.2868

+20

18

16

18.065

13 vS gbM Spiral

273

10

17

19.6

3.2865

+20

17

47

18.070

14 vS gbN

274

10

17

47.1

3.2899

+20

40

58

18.087

15 vS iF gbM

275

10

17

53.6

3.2880

+20

31

57

18.091

14 S sbM N Spiral E130°

276

10

18

7.1

3.2906

+20

47

25

18.100

13 vS sbM N Spiral

277

10

19

5.2

3.2870

+20

38

42

18.136

13 S sbM N Spiral

278

10

19

6.9

+3.2857

+20

32

21

-18.137

16 vS iF gbM

No.

α 1900.0

Precession.

δ 1900.0

Precession.

Description.

h

m

s

s

°

′

″

″

279

10

19

10.3

+3.2885

+20

47

38

-18.139

14 vS stell

280

10

19

20.6

4.5635

+69

9

51

18.149

S pF R

281

10

24

6.2

4.4863

+68

59

31

18.317

vS F E95°

282

11

1

52.7

3.5701

+55

59

0

19.407

16 vS bN iF

283

11

2

5.8

3.5753

+56

25

16

19.412

15 vS neb*

284

11

2

9.5

3.5660

+55

53

31

19.413

16 S gbM E100°

285

11

2

22.6

3.5740

+56

28

29

19.419

15 vS stell

286

11

2

54.6

3.5647

+56

11

43

19.429

15 vS sbM stell N

287

11

3

8.0

3.5613

+56

6

26

19.435

17 vS N

288

11

3

12.3

3.5620

+56

11

17

19.435

16 vS sbN R Spiral?

289

11

3

22.7

3.5523

+55

58

43

19.439

14 vS neb*

290

11

4

32.2

3.5510

+56

12

9

19.463

17 vS stell

291

11

4

44.8

3.5467

+56

4

9

19.467

15 S R sbM N Spiral

292

11

4

47.7

3.5469

+56

5

40

19.468

17 vS R neb*

293

11

4

57.3

3.5437

+55

59

16

19.471

17 vS stell

294

11

5

6.2

3.5426

+56

0

26

19.474

Two 18 mag. objects, iF, close together

295

11

5

16.1

3.5379

+55

48

58

19.478

16 vS. Uniform brightness

296

11

5

20.8

3.5431

+56

8

46

19.479

17 vS iF stell

297

11

5

22.1

3.5373

+55

49

20

19.480

15 vS R gbM N Spiral

298

11

5

35.2

3.5408

+56

8

18

19.484

16 vS R gbM

299

11

5

42.3

3.5387

+56

4

33

19.487

18 vS sbM N Ring

300

11

5

50.5

3.5412

+56

16

58

19.490

17 vS sbM N Spiral?

301

11

5

54.8

3.5299

+55

40

11

19.493

vvF E75°

302

11

5

58.2

3.5290

+55

37

33

19.494

S vF R

303

11

6

1.6

3.5352

+56

1

39

19.494

16 vS R sbM N Spiral

304

11

6

6.1

3.5322

+55

53

51

19.495

17 vS gbM iF

305

11

6

8.8

3.5347

+56

3

23

19.496

17 S vm E85°

306

11

6

12.5

3.5292

+55

45

22

19.499

vF E100° spindle shaped

307

11

6

19.1

3.5312

+55

56

37

19.500

17 vS dif

308

11

6

23.7

3.5305

+55

56

44

19.501

vS iF dif

309

11

6

27.1

3.5300

+55

56

40

19.502

17 vS gbM iF

310

11

6

28.4

3.5303

+55

58

4

19.503

16 vS sbM N Spiral

311

11

6

42.0

3.5330

+56

13

33

19.507

16 vS bM E150°

312

11

6

43.0

3.5297

+56

3

13

19.508

17 vS dif iF

313

11

6

45.0

3.5298

+56

4

18

19.508

17 vS dif iF

314

11

6

51.1

3.5313

+56

12

24

19.510

17 vS sbM N Spiral

315

11

6

55.4

3.5262

+55

57

11

19.512

16 vS R sbM N Spiral

316

11

7

6.7

3.5295

+56

13

36

19.516

13 S sbM N Spiral E70°

317

11

7

10.±

...

+56

14

0±

...

16 vS stell iF neb?

318

11

7

15.9

3.5304

+56

21

9

19.519

15 vS R sbM N Spiral

319

11

7

23.9

3.5248

+56

5

58

19.522

15 vS neb*

320

11

7

32.4

3.5239

+56

7

1

19.525

16 vS sbM N Spiral

321

11

7

57.5

3.5230

+56

15

58

19.533

16 vS gbM E25°

322

11

7

59.6

3.5172

+55

57

47

19.534

16 vS neb*

323

11

8

1.8

3.5117

+55

36

17

19.534

pB S R

324

11

8

3.4

3.5177

+56

1

13

19.536

16 vS sbM

325

11

8

4.9

3.5153

+55

51

25

19.536

S F gbM E100°

326

11

8

17.4

3.5200

+56

15

18

19.540

12 S gbN be Spiral E30°

327

11

8

25.0

3.5178

+56

12

21

19.543

17 vS stell

328

11

8

46.3

3.5117

+56

1

58

19.550

15 vS stell N

329

11

8

59.2

3.5043

+55

38

13

19.553

pB S E160°

330

11

9

10.7

3.5006

+55

30

18

19.556

B irr B*  n

331

11

9

20.7

3.5034

+55

45

42

19.559

vS B E100° bM

332

11

9

38.0

3.4948

+55

23

27

19.565

S pF R another apparently distinct neb np

333

11

9

41.7

3.5046

+56

0

2

19.566

L B pmbM R

334

11

9

56.7

3.4978

+55

43

41

19.571

vS B E135° spindle shaped

335

11

10

14.5

3.4873

+55

14

57

19.578

S B E90° gbM

336

11

10

28.9

3.4870

+55

19

48

19.581

S pF E135° companion n

337

11

10

43.8

3.4929

+55

49

55

19.587

vS F E100° bf

338

11

10

58.5

3.4913

+55

14

50

19.592

S B R vmbM

339

11

11

1.0

3.4817

+55

17

47

19.593

S B E45° bsf

340

11

11

4.2

3.4809

+55

16

23

19.594

B Spiral

341

11

11

36.5

3.4780

+55

21

45

19.604

vvF S R

342

11

12

23.8

3.4719

+55

23

11

19.619

vB S e E170°

343

11

13

21.2

3.1360

+13

15

33

19.632

B S R neb*

344

11

13

22.7

3.1362

+13

17

29

19.633

S F gbM

345

11

25

13.4

3.2933

+47

34

7

19.818

S pB N

346

11

26

40.5

3.3848

+47

39

8

19.836

vS F

347

11

27

2.8

3.2828

+47

42

13

19.840

vS F

348

11

27

10.3

+3.2774

+47

2

45

-19.842

vS F gbM

No.

α 1900.0

Precession.

δ 1900.0

Precession.

Description.

h

m

s

s

°

′

″

″

349

11

27

28.6

+3.2797

+47

38

54

-19.846

vS B vmbM Spiral

350

11

27

41.9

3.2757

+47

16

48

19.848

vS B E135°

351

11

28

18.1

3.2698

+46

59

22

19.856

vS F

352

11

28

50.2

3.2694

+47

24

46

19.862

vS B

353

11

29

23.4

3.2668

+47

32

31

19.869

vS vB N E100°

354

11

30

3.6

3.2603

+47

13

56

19.877

pS pF

355

12

10

36.7

3.0230

+38

30

36

20.026

S pB bf

356

12

10

45.3

3.0232

+38

4

44

20.025

S pB E95°

357

12

10

51.8

3.0218

+38

34

3

20.025

S pB bf

358

12

11

18.1

2.9996

+47

51

36

20.025

15 vS stell

359

12

11

27.3

2.9987

+47

49

2

20.024

15 vS E135° sbM N Spiral

360

12

11

46.7

2.9956

+48

6

2

20.022

16 S E65°

361

12

11

48.5

2.9961

+47

55

0

20.022

15 vS R sbM sN Spiral

362

12

11

50.1

3.0176

+38

27

34

20.021

S vF

363

12

12

7.0

2.9935

+48

5

58

20.020

15 vS R

364

12

12

12.2

3.0536

+14

45

22

20.019

17 vS R bM

365

12

12

16.4

3.0529

+15

10

26

20.019

18 vS R

366

12

12

19.7

3.0532

+14

54

6

20.018

18 vS R

367

12

12

23.2

3.0527

+15

11

34

20.018

18 vS vF dif

368

12

12

23.5

3.0535

+14

39

45

20.018

18 vS E160°

369

12

12

25.7

3.0529

+15

1

40

20.018

18 vS R

370

12

12

36.3

2.9903

+48

5

25

20.017

16 vS dif vgbM

371

12

12

42.0

3.0529

+14

45

51

20.016

18 vS vF R

372

12

12

44.4

3.0530

+14

38

8

20.016

18 vS dif

373

12

12

45.0

3.0145

+37

57

9

20.016

S F R

374

12

12

45.6

2.9909

+47

38

17

20.016

16 vS iF

375

12

12

51.5

3.0526

+14

44

42

20.016

18 vS R bs

376

12

12

54.4

2.9895

+47

45

31

20.016

17 vS iF dif

377

12

12

54.6

3.0523

+14

54

0

20.015

18 vS E110°

378

12

12

56.2

3.0521

+15

0

2

20.015

17 vS R bM

379

12

13

2.0

3.0519

+15

2

28

20.015

17 vS R N

380

12

13

5.6

3.0515

+15

15

4

20.014

18 vS vF dif

381

12

13

7.9

3.0518

+15

0

8

20.014

18 vS R bM

382

12

13

9.5

3.0515

+15

12

43

20.014

17 vS R N

383

12

13

13.1

3.0120

+38

6

46

20.014

vS vF

384

12

13

30.1

3.0108

+38

4

43

20.013

S F

385

12

13

33.8

3.0108

+37

57

29

20.013

pL vF R

386

12

13

36.6

3.0510

+15

4

41

20.012

18 vS R

387

12

13

37.3

3.0514

+14

47

32

20.012

18 vS R N

388

12

13

43.8

3.0512

+14

47

28

20.011

18 vS R

389

12

13

53.1

3.0505

+15

6

48

20.010

18 vS E120°

390

12

13

53.6

3.0506

+15

4

0

20.010

17 vS E100° N

391

12

13

57.4

3.0505

+15

3

34

20.010

18 vS R N

392

12

13

58.6

3.0510

+14

40

44

20.010

19 vS vF

393

12

14

5.2

3.0508

+14

41

10

20.009

18 vS R bn

394

12

14

6.2

3.0502

+15

5

31

20.009

19 vS E110° stell N

395

12

14

12.7

2.9815

+47

38

45

20.009

17 vS sbM Spiral

396

12

14

22.8

3.0497

+15

8

31

20.008

18 vS E130°

397

12

14

25.3

3.0499

+14

57

48

20.008

17 vS R N

398

12

14

31.1

3.0497

+14

58

50

20.007

18 vS R

399

12

14

44.0

3.0496

+14

50

50

20.006

18 vS R N

400

12

14

49.2

3.0489

+15

11

38

20.005

18 vS vF

401

12

15

4.9

3.0490

+14

53

4

20.004

18 vS dif

402

12

15

5.0

3.0492

+14

41

30

20.004

18 vS R two N

403

12

15

11.0

3.0643

+ 4

45

22

20.003

pF vE15°

404

12

15

11.1

3.0483

+15

13

37

20.003

17 vS E120° bM

405

12

15

22.7

3.0482

+15

6

45

20.002

17 vS R

406

12

15

31.2

3.0484

+14

47

34

20.002

18 vS E150°

407

12

15

39.3

3.0478

+15

11

10

20.001

18 vS R

408

12

16

10.5

3.0638

+ 5

11

15

19.997

F pS

409

12

16

12.4

3.0647

+ 4

37

52

19.997

vF S bn

410

12

16

31.2

3.0438

+16

32

16

19.995

16 S E0° sbM N Spiral

411

12

16

34.7

3.0442

+16

18

0

19.995

16 S sbM stell N R Spiral?

412

12

16

36.7

3.0442

+16

13

30

19.994

18 vS iF

413

12

16

49.6

3.0439

+16

12

0

19.993

17 vS gbM iF

414

12

17

3.5

3.0432

+16

21

14

19.991

18 S dif iF E135°

415

12

17

5.±

3.0446

+15

56

30±

19.991

17 vS sbM Spiral N

416

12

17

5.2

3.0431

+16

23

20

19.991

18 vs bs R

417

12

17

12.1

3.0638

+ 4

50

23

19.991

F vS l E50°

418

12

17

14.3

+3.0429

+16

21

16

19.990

17 vS dif gbM R

No.

α 1900.0

Precession.

δ 1900.0

Precession.

Description.

h

m

s

s

°

′

″

″

419

12

17

15.6

+3.0430

+16

17

18

-19.990

16S sbM N Spiral

420

12

17

21.0

3.0633

+ 5

7

14

19.990

! pB L Spiral

421

12

17

29.5

3.0639

+ 4

41

53

19.989

vF vS

422

12

17

37.0

3.0639

+ 4

41

13

19.989

vF vS 1E45°

423

12

17

57.9

3.0414

+16

27

36

19.985

17S gbM Spiral E135°

424

12

18

5.1

3.0633

+ 4

54

53

19.986

vvF vs

425

12

18

16.2

3.0411

+16

22

30

19.983

15S sbM N Spiral?

426

12

18

17.4

3.0409

+16

25

22

19.983

18vS stell N Spiral

427

12

18

19.3

3.0629

+ 5

0

40

19.983

eeF S

428

12

18

34.6

3.0352

+18

54

45

19.981

18vS R diffic

429

12

18

40.4

3.0352

+18

49

41

19.980

18vS vF E160″

430

12

19

17.4

3.0388

+16

37

37

19.976

17vS R gbN Spiral

431

12

19

45.5

3.0333

+18

45

1

19.972

15vS E45° stell N

432

12

20

0.7

3.0399

+16

15

57

19.971

18 vS iF

433

12

20

9.1

3.0374

+16

38

51

19.970

17 S gbM N E60° Spiral on edge

434

12

20

10.9

3.0372

+16

40

27

19.970

17 vS R sbM N Spiral

435

12

20

21.3

3.0322

+18

41

40

19.968

18 vS R bM

436

12

20

21.8

3.0369

+16

40

40

19.968

18 vS iF dif

437

12

20

22.8

3.0314

+19

2

32

19.968

18 vS R

438

12

20

35.2

3.0323

+18

26

52

19.966

18 vS R bM

439

12

20

40.8

3.0307

+19

4

16

19.966

18 vS vF R

440

12

21

21.9

3.0296

+18

59

58

19.960

18 vS R bM

441

12

21

39.2

3.0296

+18

41

29

19.958

18 vs R

442

12

21

55.3

3.0297

+18

35

37

19.956

17 vs R bM

443

12

21

56.5

3.0282

+19

4

14

19.956

18 vS R bM

444

12

21

59.8

3.0290

+18

42

0

19.956

18 vS E120°

445

12

22

13.3

3.0282

+18

49

7

19.954

17 vS R bM

446

12

25

24.7

3.0336

+14

42

46

19.924

14 S E60°

447

12

25

35.6

3.0320

+15

8

33

19.922

18 vS dif

448

12

25

47.1

3.0316

+15

11

13

19.921

15 vS bM iF

449

12

25

49.9

3.0317

+15

6

17

19.920

16 vS gbM

450

12

25

53.0

3.0312

+15

19

36

19.920

16 S E115° bM

451

12

26

0.9

3.0320

+14

54

29

19.918

16 vS R

452

12

26

0.9

3.0308

+15

20

0

19.918

17 vS iF bM

453

12

26

4.7

3.0323

+14

48

53

19.918

18 vS iF

454

12

26

8.1

3.0319

+14

55

14

19.917

16 vS R sbM N

455

12

26

12.2

3.0322

+14

44

59

19.916

12 neb*

456

12

26

17.2

3.0321

+14

44

55

19.916

16 vS iF gbM N

457

12

26

17.3

3.0323

+14

40

6

19.916

16 vS gbM N Spiral?

458

12

26

34.7

3.0299

+15

24

49

19.913

14 S bM E165°

459

12

26

51.1

3.0308

+14

51

34

19.910

15 L m E80° bM N Spiral on edge

460

12

27

26.5

3.0636

+ 3

8

36

19.904

17 vS E80° gbM Spiral on edge?

461

12

27

30.4

3.0634

+ 3

12

55

19.903

15 L vm E40° small spur from M

462

12

27

31.7

3.0290

+15

7

56

19.903

16 vS

463

12

27

31.8

3.0623

+ 3

34

13

19.903

17 vS gbM iF

464

12

27

39.2

3.0304

+14

36

16

19.902

11 L bM iF sc

465

12

27

41.6

3.0299

+14

44

55

19.902

11 neb*

466

12

27

44.2

3.0629

+ 3

21

0

19.900

17 vS vgbM iF

467

12

27

45.0

3.0634

+ 3

10

55

19.900

17 vS vgbM

468

12

27

55.1

3.0641

+ 2

53

13

19.899

18 vS R (Ring?)

469

12

28

10.1

3.0646

+ 2

42

3

19.896

17 vS R

470

12

28

18.2

3.0646

+ 2

42

24

19.894

16 vS ◯

471

12

28

26.5

3.0648

+ 2

50

47

19.893

17 vS E150°

472

12

28

35.9

3.0645

+ 2

41

20

19.891

17 vS E160° N

473

12

28

37.4

3.0272

+15

10

32

19.891

16 vS sbM N Spiral E50°

474

12

28

43.8

3.0653

+ 2

25

53

19.890

16 vS gbM

475

12

28

44.0

3.0646

+ 2

49

52

19.890

17 vS R bM

476

12

23

50.7

3.0653

+ 2

24

19

19.888

18 vS vF R

477

12

28

54.3

3.0267

+15

11

50

19.887

18 vS sbM N Ring?

478

12

28

55.5

3.0656

+ 2

19

2

19.887

18 vS dif

479

12

28

58.5

3.0644

+ 2

41

54

19.887

18 vS E130° N

480

12

29

1.7

3.0653

+ 2

23

42

19.886

17 vS R

481

12

29

8.9

3.0266

+15

6

23

19.885

16 vS sbM N Spiral

482

12

29

15.8

3.0614

+ 3

39

39

19.883

17 vS stell

483

12

29

15.8

3.0615

+ 3

39

15

19.883

18 vS N? Spiral?

484

12

29

27.0

3.0635

+ 2

58

4

19.881

18 vS dif iF

485

12

29

28.7

3.0636

+ 3

7

14

19.881

17 vS sbM N Spiral

486

12

29

30.5

3.0650

+ 2

27

49

19.881

17 vS R stell N

487

12

29

40.8

3.0616

+ 3

33

41

19.879

17 vS bM N Spiral

488

12

29

42.7

+3.0635

+ 2

55

34

-19.879

17 vS R

No.

α 1900.0

Precession.

δ 1900.0

Precession.

Description.

h

m

s

s

°

′

″

″

489

12

29

45.4

+3.0650

+ 2

26

4

-19.878

17 vS E90° N

490

12

29

51.4

3.0620

+ 3

24

29

19.877

17 vS iF

491

12

29

55.3

3.0652

+ 2

21

0

19.876

17 vS R N

492

12

29

56.6

3.0632

+ 3

0

22

19.876

18 vS R N

493

12

29

57.1

3.0652

+ 2

20

13

19.876

17 vS R

494

12

29

58.5

3.0653

+ 2

19

14

19.876

18 vS R

495

12

30

3.3

2.9859

+26

19

54

19.875

15 vS R bM

496

12

30

4.2

3.0652

+ 2

20

7

19.875

18 vS R

497

12

30

6.6

3.0616

+ 3

33

6

19.874

17 vS bs iF

498

12

30

11.2

3.0616

+ 3

30

36

19.873

17 vS stell

499

12

30

12.4

3.0649

+ 2

25

7

19.873

18 vS R

500

12

30

12.8

2.9853

+26

22

24

19.873

17 VS R bM

501

12

30

14.8

3.0648

+ 2

26

29

19.873

18 vS E70°

502

12

30

27.3

3.0648

+ 2

26

16

19.870

18 vS R bM

503

12

30

28.4

3.0648

+ 2

26

41

19.870

17 vS R bM

504

12

30

29.0

3.0651

+ 2

19

36

19.870

16 vS R

505

12

30

30.6

3.0613

+ 3

35

6

19.870

15 L vm E165° sbM Spiral

506

12

30

32.2

3.0650

+ 2

22

17

19.869

18 vS R bM

507

12

30

35.8

3.0642

+ 2

37

39

19.869

18 vS R

508

12

30

36.8

2.9840

+26

24

5

19.868

14 S E135° N

509

12

30

39.5

3.0643

+ 2

34

35

19.868

18 vS R

510

12

30

39.7

3.0645

+ 2

29

55

19.868

18 vS R

511

12

30

42.6

3.0648

+ 2

25

14

19.867

18 vS R bM

512

12

30

43.7

2.9819

+26

50

17

19.867

17 vS E40°

513

12

30

44.2

2.9822

+26

46

25

19.867

15 vS N E50°

514

12

30

52.0

3.0648

+ 2

22

56

19.866

17 vS R

515

12

30

52.6

3.0619

+ 3

19

59

19.866

17 vS sbM Spiral E110°

516

12

31

22.5

2.9809

+26

38

7

19.859

18 vS R

517

12

31

32.7

2.9797

+26

47

58

19.857

18 vS R

518

12

31

39.6

2.9794

+26

47

9

19.856

16 vS R N

519

12

31

46.1

2.9796

+26

39

51

19.855

17 vS R N

520

12

32

6.9

2.9787

+26

38

28

19.850

17 vS R N

521

12

32

21.2

2.9784

+26

31

56

19.848

18 vS vF R

522

12

32

22.7

2.9777

+26

42

36

19.847

18 vS R bM

523

12

22

29.7

2.9777

+26

37

36

19.846

18 vS R bM

524

12

32

34.2

2.9780

+26

28

24

19.845

16 neb*

525

12

32

49.7

2.9758

+26

50

59

19.842

18 vS vF E135° D

526

12

35

41.0

2.9371

+33

7

48

19.805

16 vS E140° bM

527

12

36

34.4

2.9348

+32

56

17

19.792

17 vS R bM

528

12

36

45.3

2.9340

+32

56

48

19.790

18 vS E80°

529

12

36

54.9

2.9309

+33

24

23

19.787

17 vS E0° D

530

12

37

14.3

2.9303

+33

18

35

19.781

15 vS E125° N Spiral on edge

531

12

38

9.9

2.9291

+32

52

38

19.770

18 vS bM E140°

532

12

38

13.8

2.9277

+33

6

12

19.769

18 vS R

533

12

38

15.0

2.9279

+33

2

21

19.768

14 vS E145° bM

534

12

38

33.3

2.9247

+33

26

3

19.764

15 neb*

535

12

38

35.6

2.9268

+33

0

52

19.764

16 neb*

536

12

38

41.7

2.9267

+32

56

47

19.762

18 vS R

537

12

38

45.4

2.9259

+33

2

53

19.761

18 vS R

538

12

44

9.3

2.8448

+41

38

45

19.677

18 vS R N

539

12

44

30.5

2.8431

+41

38

16

19.670

15 vS E60° Spiral?

540

12

44

31.8

2.8425

+41

41

45

19.670

18 vS vR dif

541

12

44

36.3

2.8424

+41

39

31

19.669

18 vS vF R diffic

542

12

44

39.0

2.8418

+41

41

51

19.668

18 vS R diffic

543

12

44

46.6

2.8401

+41

49

26

19.666

17 vS R bM

544

12

44

46.9

2.9440

+26

19

4

19.666

16 vS E60° bM

545

12

44

47.5

2.8417

+41

23

51

19.666

18 vS R bM

546

12

44

52.4

2.8423

+41

30

43

19.664

17 vS R

547

12

44

55.4

2.8398

+41

46

30

19.663

18 vS vF R diffic

548

12

44

56.5

2.8426

+41

25

53

19.663

18 vS R

549

12

45

8.4

2.8376

+41

54

40

19.659

18 vS vF dif D?

550

12

45

16.5

2.8412

+41

23

26

19.657

16 vS E80° bM Spiral?

551

12

45

16.9

2.9453

+25

50

0

19.657

17 vS R bM

552

12

45

21.5

2.8404

+41

26

8

19.656

16 vS R bM

553

12

45

27.0

2.8395

+41

29

21

19.654

18 vS vF E150° bM Spiral on edge

554

12

45

28.2

2.9448

+25

50

38

19.654

18 vS R

555

12

45

29.3

2.9442

+26

13

28

19.653

17 vS E50° bs

556

12

45

30.5

2.9444

+26

14

10

19.653

17 vS R

557

12

45

43.2

2.8361

+41

44

11

19.649

17 vS R N

558

12

45

56.5

2.9436

+25

49

14

19.646

16 vS E40° N

No.

α 1900.0

Precession.

δ 1900.0

Precession.

Description.

h

m

s

s

°

′

″

″

559

12

45

58.3

+2.9436

+25

48

13

-19.645

16 vS E35° N

560

15

45

59.1

2.8368

+41

29

16

19.645

18 vS vF R

561

12

46

10.3

2.8363

+41

25

57

19.641

18 vS vF R bM

562

12

46

22.3

2.8331

+41

56

7

19.638

15 vS E90° bs Spiral?

563

12

46

22.8

2.8358

+41

22

17

19.638

18 vS vF R ◯?

564

12

46

26.4

2.8328

+41

41

43

19.637

17 vS R bM

565

12

46

26.6

2.8335

+41

35

39

19.637

18 vS R bM

566

12

46

37.8

2.8325

+41

36

5

19.633

18 vS R bM

567

12

46

46.6

2.9393

+26

9

36

19.631

16 vS E150° bM

568

12

47

5.2

2.8321

+41

22

31

19.625

18 vS R

569

12

47

13.3

2.8269

+41

54

46

19.623

17 vS R bM

570

12

47

14.6

2.8309

+41

24

52

19.622

17 vS R bM

571

12

47

24.3

2.8272

+41

46

30

19.620

18 vS R bM

572

12

47

29.8

2.8254

+41

56

1

19.618

18 vS R

573

12

47

31.6

2.9395

+25

45

4

19.618

16 vS E10° N

574

12

47

38.9

2.8258

+41

47

20

19.615

18 vS R N

575

12

47

43.7

2.8260

+41

42

48

19.614

18 vS R bM

576

12

47

53.5

2.8245

+41

48

10

19.611

18 vS dif

577

12

48

1.6

2.8256

+41

34

23

19.609

16 vS E125° bM

578

12

48

17.5

2.8252

+41

27

34

19.604

18 vS R

579

12

48

25.4

2.8217

+41

48

40

19.602

18 vS vF R

580

12

48

30.9

2.8246

+41

23

31

19.600

17 vS R N

581

12

48

31.3

2.8206

+41

53

17

19.600

18 vS vF R

582

12

48

32.9

2.8244

+41

23

30

19.600

16 vS R N

583

12

50

50.7

2.9509

+22

25

55

19.557

S R vF

584

12

51

15.7

2.9504

+22

21

0

19.549

vS vF E90°

585

13

9

17.4

2.7068

+42

33

56

19.139

18 vS R

586

13

9

24.6

2.7039

+42

44

21

19.135

14 S E150° four N

587

13

9

25.1

2.7071

+42

30

1

19.135

18 vS R

588

13

9

30.5

2.7093

+42

18

5

19.133

17 vS R bM

589

13

9

35.1

2.7083

+42

20

47

19.131

17 vS R bM

590

13

9

36.1

2.7089

+42

17

28

19.130

17 vS R bM

591

13

9

38.6

2.7084

+42

19

5

19.129

18 vS R bM

592

13

9

43.4

2.7086

+42

15

56

19.127

18 vS R

593

13

9

46.8

2.7056

+42

28

13

19.125

17 vS E120°

594

13

9

47.8

2.7078

+42

18

1

19.125

16 vS E150° bM

595

13

9

53.2

2.7077

+42

16

31

19.123

18 vS R bM

596

13

9

53.3

2.7086

+42

12

19

19.123

18 vS vF R

597

13

9

56.2

2.7042

+42

28

40

19.121

16 vS E90° bM

598

13

9

57.3

2.7028

+42

36

34

19.121

18 vS R

599

13

10

1.3

2.7084

+42

10

13

19.119

14 vS E15° gbM

600

13

10

4.6

2.7015

+42

40

5

19.117

18 vS R

601

13

10

5.4

2.6999

+42

47

12

19.117

16 vS R bM neb*  ?

602

13

10

5.7

2.7054

+42

22

10

19.117

18 vS R

603

13

10

5.8

2.7061

+42

18

47

19.117

17 vS R bM

604

13

10

5.8

2.7014

+42

37

56

19.117

18 vS R N

605

13

10

7.0

2.7032

+42

31

16

19.116

17 vS E165° gbM

606

13

10

11.5

2.7018

+42

35

45

19.114

18 vS R bM

607

13

10

11.7

2.7030

+42

30

44

19.114

18 vS E50°

608

13

10

12.4

2.7030

+42

30

7

19.114

18 vS R

609

13

10

12.8

2.7009

+42

39

44

19.114

18 vS R

610

13

10

14.1

2.7027

+42

31

8

19.113

18 vS R vF

611

13

10

16.2

2.7027

+42

30

10

19.112

18 vS E70° bM

612

13

10

21.0

2.7057

+42

14

33

19.110

14 neb*

613

13

10

22.6

2.7064

+42

10

52

19.110

18 vS vF R

614

13

10

31.3

2.7009

+42

32

28

19.105

17 vS R bM

615

13

10

32.5

2.6979

+42

45

51

19.105

18 vS R

616

13

10

38.2

2.7026

+42

22

18

19.102

18 vS R bM

617

13

10

38.9

2.7042

+42

14

22

19.102

18 vS R

618

13

10

41.2

2.7033

+42

17

50

17.101

17 vS E150° gbM

619

13

10

43.5

2.7016

+42

24

33

19.100

18 vS E80°

620

13

10

47.8

2.7041

+42

11

39

19.098

18 vS vF R

621

13

10

51.4

2.6951

+42

51

13

19.096

16 vS E75° gbM

622

13

10

53.8

2.6947

+42

52

3

19.095

17 vS E150° bM

623

13

10

57.6

2.7032

+42

11

42

19.094

18 vS R

624

13

10

58.1

2.7007

+42

22

50

19.094

17 vS R bM

625

13

11

3.2

2.7008

+42

20

46

19.091

18 vS R

626

13

11

5.9

2.7011

+42

17

58

19.090

18 vS E30°

627

13

11

8.3

2.7022

+42

12

22

19.089

17 vS R bM

628

13

11

9.6

+2.7002

+42

20

44

-19.088

18 vS vF R

No.

α 1900.0

Precession.

δ 1900.0

Precession.

Description.

h

m

s

s

°

′

″

″

629

13

11

15.1

+2.7001

+42

19

9

-19.086

18 vS R bM

630

13

11

19.7

2.7017

+42

10

0

19.084

18 vS E35°

631

13

11

21.3

2.6978

+42

27

13

19.083

17 vS E100° bM

632

13

11

27.5

2.6973

+42

27

7

19.080

17 vS E60° gbM

633

13

11

29.8

2.6982

+42

22

18

19.079

18 vS R

634

13

11

30.7

2.6978

+42

23

27

19.079

17 vS E75°

635

13

11

36.8

2.6985

+42

17

58

19.076

17 vS R N

636

13

11

38.3

2.6935

+42

40

21

19.075

18 vS R

637

13

11

38.6

2.6973

+42

22

44

19.075

18 vS E110°

638

13

11

40.2

2.6925

+42

43

58

19.075

18 vS E125°

639

13

11

43.0

2.6960

+42

27

5

19.073

17 vS E130° gbM

640

13

11

44.1

2.6972

+42

21

11

19.073

18 vS R

641

13

11

50.0

2.6933

+42

36

47

19.070

17 vS R bM

642

13

11

51.6

2.6967

+42

20

17

19.070

17 vS R bM

643

13

11

53.9

2.6963

+42

21

24

19.068

18 vS R bM

644

13

11

54.9

2.6964

+42

20

41

19.068

18 vS R bM

645

13

11

57.0

2.6963

+42

20

7

19.067

17 vS E110° gbM

646

13

11

58.6

2.6949

+42

25

54

19.066

18 vS R

647

13

12

15.4

2.6903

+42

40

36

29.0S9

18 vS R

648

13

12

24.1

2.6907

+42

35

22

19.055

17 vS R N

649

13

12

29.4

2.6861

+42

54

15

19.053

17 vS E130°

650

13

12

37.4

2.6880

+42

42

38

19.049

16 vS R bM neb*  ?

651

13

12

38.9

2.6893

+42

35

47

19.048

18 vS R

652

13

12

39.7

2.6862

+42

49

45

19.048

27 vS E45°

653

13

12

44.7

2.6885

+42

37

23

19.046

18 vS R

654

13

12

56.6

2.6872

+42

38

34

19.040

18 vS R

655

13

13

4.2

2.6861

+42

40

46

19.037

18 vS R

656

13

13

11.7

2.6913

+42

13

29

19.033

17 vS R bM

657

13

13

11.8

2.6850

+42

42

56

19.033

18 vS vF dif

658

13

13

19.6

2.6877

+42

27

12

19.030

18 vS E160°

659

13

13

21.4

2.6829

+42

48

36

19.029

18 vS R

660

13

13

22.0

2.6878

+42

25

44

19.029

18 vS R

661

13

13

22.8

2.6837

+42

44

34

19.029

17 vS R N

662

13

13

28.2

2.6825

+42

47

49

19.026

18 vS vF R

663

13

13

36.3

2.6830

+42

42

9

19.023

17 vS R bM

664

13

13

57.0

2.6802

+42

47

4

19.014

18 vS R

665

13

14

2.4

2.6802

+42

44

54

19.011

17 vS R bM

666

13

23

5.2

2.5574

+47

23

8

18.746

vS eeF

667

13

24

19.1

2.5489

+47

26

42

18.707

B pL E80°

668

13

26

4.1

2.5313

+47

49

42

18.651

vS eF

669

13

26

15.2

2.5313

+47

45

47

18.644

S pB l E135°

670

13

27

7.8

2.5273

+47

41

54

18.616

S eeF

671

23

27

19.5

2.5333

+47

18

40

18.610

F S R

672

23

27

33.2

2.5315

+47

20

14

18.602

vS vF E90°

673

13

31

34.8

3.2319

-17

4

23

18.468

16 vS E150°

674

13

31

38.8

3.2351

-17

22

4

18.466

16 vS E150° bM

675

13

31

47.9

3.2332

-17

9

33

18.460

18 vS R

676

13

31

52.4

3.2335

-17

10

52

18.458

18 vS E50°

677

13

31

52.5

3.2339

-17

12

47

18.458

18 vS bn dif

678

13

32

54.9

3.2386

-17

29

57

18.422

17 vS bM E105°

679

13

57

42.5

2.1379

+54

54

5

17.461

B S E90° neb*  ?

680

14

1

50.9

2.1136

+54

44

50

17.280

S pF bp

681

14

2

3.1

2.1055

+54

56

17

17.272

pB L i

682

15

0

8.1

1.6712

+55

59

2

14.170

18 vS R bM

683

15

0

32.4

1.6694

+55

58

21

14.144

18 vS vF E110°

684

15

0

33.7

1.6634

+56

4

52

14.143

17 vS E160°

685

15

1

2.9

1.6722

+55

51

53

14.113

17 vS R bM

686

25

1

4.1

1.6638

+56

0

58

14.111

17 vS R bM

687

15

1

30.4

2.7322

+19

40

56

14.082

S R F

688

15

1

32.3

2.7225

+20

11

15

14.080

S pF E45°

689

25

1

37.2

2.7251

+20

3

1

14.075

vS F E10°

690

15

2

31.5

1.6443

+56

12

53

14.018

16 vS R bM

691

15

2

49.2

2.7273

+19

49

56

13.999

pS F gbM

692

15

2

59.6

1.6345

+56

20

44

13.989

17 vS R bs

693

25

3

18.1

1.6535

+55

57

34

13.970

13 neb*

694

15

3

29.0

2.7243

+19

56

29

13.958

vF S R

695

25

3

30.9

1.6493

+56

0

49

13.956

16 vS N E105°

696

15

3

34.9

2.7213

+20

5

39

13.952

vS F E45°

697

15

3

40.9

2.7207

+20

7

7

13.946

vF pL Spiral

698

15

3

47.8

+1.6564

+55

51

5

-13.939

17 vS E45°

No.

α 1900.0

Precession.

δ 1900.0

Precession.

Description.

h

m

s

s

°

′

″

″

699

15

3

54.2

+1.6479

+55

59

40

-13.932

17 vS bM E135°

699

15

3

54.22

+1.64792

+55

59

40

-13.932

17 vS bM E135°

700

15

3

56.82

2.72422

+19

54

41

13.929

vS F

701

15

4

23.72

2.72812

+19

40

23

13.901

F pL gbM Spiral?

702

15

4

28.22

2.72482

+19

50

25

13.896

pB S E90°

703

15

4

31.92

1.65632

+55

46

6

13.892

18 vS E35°

704

15

5

45.52

1.62772

+56

20

45

13.815

17 vS R N

705

15

5

52.12

1.64012

+55

55

5

13.807

18 vS R N

706

15

6

37.42

1.62632

+56

5

17

-13.760

18 vS R bM

707

22

29

41.02

2.72142

+34

22

53

+18.513

F S E90°

708

22

30

38.12

2.72992

+33

58

36

18.544

F S R

709

22

30

54.82

2.73062

+34

0

21

18.552

F pS vmbM

710

22

31

3.12

2.73442

+33

44

58

18.557

pB vS m E90° vmbM

711

22

31

17.62

2.73032

+34

8

35

18.566

vF vS m E160°

712

22

31

43.92

2.73342

+34

1

32

18.579

F pL i*   inv

713

22

32

1.52

2.73942

+33

42

15

18.588

vF S m E140°

714

22

32

29.82

2.73242

+34

19

13

18.603

pB vS gmbM

715

22

32

33.22

2.73542

+34

6

5

18.605

vF pL gbM

716

22

32

46.22

2.73932

+33

51

20

18.612

D* inv set on p*

717

22

32

50.32

2.73472

+34

13

53

18.614

pB S E0° vmbM

718

22

33

1.32

2.74062

+34

19

38

18.620

vB S l E50° vmbM

719

22

33

37.72

2.73612

+34

21

1

18.640

pF pL l E90°

720

22

33

50.52

2.74482

+33

43

16

18.647

Neb*

721

22

33

58.12

2.74102

+34

4

9

18.651

vF pS E45°

722

22

34

0.62

2.74422

+33

49

6

18.652

F S E20°

723

22

34

10.82

2.74532

+33

46

59

18.658

F pL gbM

724

23

8

29.32

3.05142

+ 4

0

38

19.543

B vS E135°

725

23

8

49.62

3.04992

+ 4

20

26

19.549

vvF S R

726

23

9

42.02

3.05152

+ 4

5

43

19.566

B S vE 170°

727

23

10

1.12

3.0529

+ 3

49

42

19.572

B S neb*

728

23

10

24.42

3.05042

+ 4

21

20

19.580

B neb*

729

23

10

28.12

3.05012

+ 4

25

14

19.581

pS vF i

730

23

11

11.52

3.05212

+ 4

5

19

19.594

S l E90°

731

23

47

4.62

3.06202

+ 7

50

21

20.016

F pL N Spiral?

732

23

48

15.72

3.06322

+ 7

35

32

20.021

vF BN E100° Spiral

733

23

49

39.32

3.06402

+ 7

49

26

20.027

F vS mbM l E45°

734

23

56

13.32

3.06612

+15

55

34

20.045

vvF vS

735

23

56

16.02

3.06632

+15

43

36

20.045

pB vS

736

23

56

36.92

3.06682

+15

45

12

20.045

F vS

737

23

56

40.12

3.06692

+15

45

59

20.045

F vS E60°

738

23

56

52.92

3.06572

+20

25

57

20.046

S vF F*   sp

739

23

57

4.82

3.06762

+15

49

9

20.046

vF pS

740

23

58

4.02

3.06922

+15

24

34

20.046

B m E135° N

741

23

58

18.12

3.06862

+20

47

8

20.047

vS vF E45°

742

23

58

53.32

3.07052

+15

27

48

20.047

F vS

743

23

59

20.82

3.07132

+15

25

32

20.047

vvF vS

744

23

59

23.22

+3.07102

+20

9

40

+20.047

S F E170°

ABBREVIATIONS USED IN DESCRIPTION.

The number denotes magnitude,—estimated from the negative.

vS

very small, < 30″

S

small, 30″ to 2′ or 3′

L

large, > 2′ or 3′

B

bright

D

double

E

elongated

F

faint

iF

irregular figure

M

middle or in the middle

N

nucleus

R

round

b

brighter

bn

brighter toward the north side

bs

brighter toward the south side

bp

brighter toward the preceding side

bf

brighter toward the following side

bsw

brightest toward the south-west

bM

brighter toward the middle

dif

diffused

diffic

difficult

eF

extremely faint

g

gradually

i

irregular

l

little

m

much

p

pretty

pB

pretty bright

pF

pretty faint

sc

scattered

stell

stellar

sbM

suddenly brighter toward the middle

v

very

vbM

very much brighter toward the middle

vS

very small

F*inv

faint star involved

◯

planetary

POSITIONS OF KNOWN NEBULÆ DETERMINED FROM THE CROSSLEY NEGATIVES.

N.G.C.

α 1900.0

Precession.

δ 1900.0

Precession.

Remarks.

h

m

s

s

°

′

″

″

185

0

33

27.9

+3.2866

+47

47

8

+19.840

247

0

42

11.0

2.9770

-21

18

21

19.708

253

0

42

38.6

2.9526

-25

50

4

19.701

509

1

18

9.6

3.1429

+ 8

54

40

18.894

516

1

18

53.2

3.1444

+ 9

1

46

18.876

518

1

19

3.0

3.1428

+ 8

48

32

18.871

522

1

19

30.6

3.1486

+ 9

28

19

18.857

524

1

19

33.0

3.1414

+ 9

1

2

18.856

525

1

19

37.9

3.1464

+ 9

10

54

18.854

532

1

20

2.5

3.1430

+ 8

44

35

18.841

...

1

21

7.3

3.1493

+ 9

23

21

18.810

N. G. C. Sup. 114

628

1

31

24.8

3.2141

+15

16

22

18.473

891

2

16

17.7

3.7447

+41

53

44

16.609

906

2

18

59.5

3.7502

+41

38

10

16.476

1023

2

34

8.1

3.7387

+38

37

42

15.681

1055

2

36

37.5

3.0739

+ 0

0

48

15.545

1068

2

37

33.7

3.0658

-  0

26

23

15.493

1072

2

38

23.7

3.0715

-  0

7

8

15.447

1084

2

41

4.5

2.9513

-  7

59

56

15.300

1638

4

36

33.4

3.0287

-  2

0

6

7.139

1931

5

24

48.7

3.9695

+34

10

7

+ 3.067

2366

7

18

19.3

6.4249

+69

24

51

- 6.718

2371-2

7

19

16.4

3.7891

+29

41

13

6.797

2403

7

27

11.7

5.8367

+65

49

13

7.445

2624

8

32

24.2

3.4566

+20

4

24

12.370

2683

8

46

27.6

3.7417

+33

47

51

13.317

2841

9

15

7.8

4.1755

+51

24

3

15.080

2903, 5

9

26

30.4

3.4065

+21

56

15

15.716

N. G. C. 2903 and 2905

3003

9

42

39.1

3.5786

+33

53

9

16.553

3021

9

45

1.0

3.5735

+34

1

14

16.670

3031

9

47

17.9

5.0430

+69

32

14

16.785

3079

9

55

11.4

4.1050

+56

9

34

17.147

3115

10

0

15.1

2.9877

-  7

14

6

17.372

3156

10

7

30.5

3.1107

+ 3

37

29

17.680

3166

10

8

34.9

3.1143

+ 3

55

11

17.724

3169

10

9

4.2

3.1154

+ 3

57

41

17.744

3184

10

12

17.4

3.6158

+41

55

27

17.874

3198

10

13

47.9

3.6919

+46

3

3

17.933

3222

10

17

6.5

3.2879

+20

23

30

18.062

3227

10

17

59.1

3.2864

+20

24

14

18.094

3226

10

18

2.8

3.2859

+20

22

13

18.097

...

10

20

55.2

4.5248

+68

55

14

18.204

Coddington’s Neb. in Ursa Major  .

3556

11

5

36.8

3.5420

+56

13

0

19.485

3587

11

9

0.1

3.5029

+55

33

47

19.553

3623

11

13

42.8

3.1374

+13

38

23

19.639

3627

11

15

2.2

3.1352

+13

32

18

19.662

3726

11

27

55.4

3.2764

+47

34

50

19.851

4226

12

11

28.2

2.9995

+47

34

53

20.024

4231

12

11

51.1

2.9956

+48

0

46

20.022

4232

12

11

51.2

2.9957

+47

59

39

20.022

4244

12

12

29.4

3.0148

+38

24

34

20.017

4248

12

12

53.1

2.9890

+47

57

52

20.016

4254

12

13

45.0

3.0509

+14

58

19

20.011

4258

12

14

0.8

2.9821

+47

51

35

20.010

4292

12

16

10.3

3.0639

+ 5

9

1

19.997

4303

12

16

48.7

3.0637

+ 5

1

42

19.993

4321

12

17

51.0

3.0418

+16

22

36

19.986

4379

12

20

11.2

3.0382

+16

9

43

19.970

4382

12

20

21.3

3.0321

+18

44

45

19.968

4394

12

20

53.0

3.0310

+18

46

7

19.964

4501

12

26

56.6

3.0304

+14

58

21

19.909

4516

12

28

5.1

3.0282

+15

7

38

19.898

4527

12

29

2.2

3.0629

+ 3

12

19

19.886

4533

12

29

15.6

3.0638

+ 2

52

39

19.884

4536

12

29

20.6

3.0642

+ 2

44

22

19.883

4565

12

31

23.3

2.9812

+26

32

20

19.859

4627

12

37

7.3

2.9316

+33

7

22

19.784

4631

12

37

14.4

+2.9315

+33

5

19

-19.783

4712

12

44

40.3

+2.9475

+26

0

55

-19.667

4725

12

45

33.0

2.9434

+26

2

44

19.652

4736

12

46

10.5

2.8344

+41

39

54

19.641

4747

12

46

52.4

2.9381

+26

19

8

19.629

4826

12

51

49.1

2.9499

+22

13

30

19.538

5055

13

11

20.5

2.6965

+42

33

28

19.083

5194

13

25

40.1

2.5358

+47

42

43

18.663

5247

13

32

38.6

3.2368

-17

22

28

18.431

5457

13

59

40.4

2.1264

+54

49

44

17.375

5857

15

2

54.8

2.7244

+19

58

56

13.993

5859

15

3

2.2

2.7245

+19

58

1

13.986

5866

15

3

45.3

1.6405

+56

8

54

13.941

5870

15

3

48.5

1.6556

+55

51

50

-13.938

7315

22

30

53.4

2.7270

+34

17

8

+18.552

7331

22

32

24.5

2.7374

+33

53

55

18.600

7333

22

32

40.1

2.7380

+33

55

44

18.609

7336

22

32

42.6

2.7377

+33

57

47

18.610

7340

22

33

4.7

2.7399

+33

53

28

18.622

7537

23

9

29.3

3.0521

+ 3

57

14

19.562

7541

23

9

38.7

3.0520

+ 3

59

21

19.565

7778

23

48

12.9

3.0635

+ 7

18

55

20.021

7779

23

48

20.0

3.0636

+ 7

19

12

20.021

7780

23

48

25.5

3.0633

+ 7

33

44

20.021

7781

23

48

39.2

3.0638

+ 7

18

17

20.022

7782

23

48

47.1

3.0638

+ 7

24

52

20.023

7814

23

58

7.5

3.0693

+15

35

20

20.046

7817

23

58

51.2

3.0699

+20

11

46

20.047

LIST OF ILLUSTRATIONS.

No.

N.G.C.

No.

Date.

Exposure.

Enlargement.

Orientation

Top.

Remarks

h

m

1

224

1899, September

7

3

0

2.0

W

Great nebula in Andromeda  .

2

253

1902, December

18-20

3

0

2.5

S

H V, 1.

3

598

1899, September

12

3

30

2.1

W

M 33.

4

628

1899, October

31

4

0

3.4

S

M 74.

5

650

1899, September

11

3

0

3.4

S

M 76.

6

891

1899, November

6

4

0

3.4

S

H V, 19.

7

1068

1899, December

3

3

0

7.2

S

M 77.

8

..

1899, December

28

4

0

2.1

W

Pleiades  .

9

1952

1899, December

24

2

0

3.4

S

Crab nebula.

10

..

1898, November

16

0

40

2.2

S

Great nebula in Orion  .

11

..

1899, February

9

0

5

2.5

S

Great nebula in Orion  .

12

1977

1900, January

21

2

50

2.4

S

H V, 30.

13

2024

1902, January

28

3

0

2.4

S

H V, 28.

14

2068

1902, November

26

3

0

2.4

S

M 78.

15

2264

1903, February

23

3

0

2.5

S

Nebula near 15 Monocerotis  .

16

..

1903, February

26

4

0

2.5

S

New nebula in Monoceros   (Roberts).

17

2403

1900, February

27

4

0

3.4

S

H V, 44.

18

2683

1900, February

23

3

20

3.3

S

H I, 200.

19

2841

1901, April

17

3

0

3.4

S

H I, 205.

20

2903-5

1900, February

24

3

30

3.4

S

H I, 56, 57.

21

3031

1900, March

21

3

55

3.4

S

M 81.

22

3115

1901, April

9

2

30

5.0

S

H I, 163.

23

3198

1900, March

24

4

0

4.3

S

H I, 199.

24

3226-7

1901, April

10

3

0

3.4

S

H II, 28, 29.

25  1

3242   {

1901, April

9

0

1

20

S

H IV, 27.

25  2

1901, April

8

0

10

20

S

H IV, 27.

26

3556

1902, May

3

4

0

3.3

S

H V, 46.

27

3587

1900, March

28

4

0

3.3

S

Owl nebula.

28

3623

1900, April

23

3

30

3.8

S

M 65.

29

3627

1900, April

23

3

30

4.3

S

M 66.

30  A

3726

1900, March

29

4

0

4.9

S

H II, 730.

30  B

3726

1900, March

29

4

0

4.9

S

H II, 730.

31

4244

1900, March

30

3

0

3.7

S

H V, 41.

32

4254

1902, June

7

3

19

3.7

S

M 99.

33

4258

1903, May

23

3

53

3.8

S

H V, 43.

34

4303

1900, April

27

3

0

3.4

S

M 61.

35

4321

1901, April

19

3

0

4.2

S

M 100.

36

4485-90

1901, April

17

1

45

4.4

S

H I, 197-8.

37

4501

1902, June

27-28

3

0

3.9

S

M 88.

38

4536

1903, May

27

3

30

3.3

S

H V, 2.

39

4559

1901, May

9

3

0

3.4

S

H I, 92.

40

4565

1901, April

21

3

0

3.3

S

H V, 24.

41

4631

1902, June

6

3

0

3.3

S

H V, 42.

42

4725

1902, June

30-July 2

3

32

3.4

S

H I, 84.

43

4736

1902, July

7

0

30

3.3

S

M 94.

44

4736

1902, July

4

3

0

3.3

S

M 94.

45

4826

1900, May

27

2

30

3.8

S

M 64.

46

5055

1902, July

5

3

30

3.3

S

M 63.

47

5194-5

1899, May

10

4

0

3.3

S

M 51.

48

5272

1900, May

22

1

30

3.8

S

M 3.

49

5457-8

1899, June

8

4

0

3.2

S

M 101.

50

5857-9

1900, May

31

2

30

7.2

S

H II, 751-2.

51

5866

1902, July

28

3

0

4.9

S

H I, 215.

52

5904

1900, May

24

1

30

3.7

S

M 5.

53

6205

1900, June

22

2

0

3.8

S

M 13.

54

6218

1899, July

11

2

0

3.7

S

M 12.

55

6514

1899, July

6

3

0

4.1

S

Trifid nebula.

56

6523

1899, July

7

4

0

2.0

W

M 8.

57

6543

1899, August

8

0

5

19

S

H IV, 37.

58

6618

1899, July

9

4

0

3.1

S

Omega nebula.

59

6720

1899, July

14

0

10

13

S

M 57.

60

6853

1899, July

31

3

0

3.8

S

Dumb-Bell nebula.

61

6894

1899, August

9

1

0

7.2

S

H IV, 13.

62

6946

1899, August

7

4

0

3.9

S

H IV, 76.

63

6995

1899, August

29

4

0

2.2

S

Network nebula in Cygnus  .

64

7009   {

1899, July

28

0

10

}  17

S {

H IV, 1.

1899, July

30

0

2

H IV, 1.

65

7023

1903, August

19-20

3

0

3.8

S

H IV, 74.

66

7217

1899, August

12

4

0

7.1

S

H II, 207.

67

7331

1899, August

11

4

0

3.8

S

H I, 53.

68

7479

1899, August

9

2

0

4.8

S

H I, 55.

69

7662

1899, September

5

{

10s

}  17

S

H, IV, 18.

20s

30s

1m

2m

70

7814

1899, September

30

3

0

4.9

S

H II, 240.

Plate 1

THE GREAT NEBULA IN ANDROMEDA

Plate 2

THE SPIRAL NEBULA H.V.I. CETI

Plate 3

THE SPIRAL NEBULA M.33 TRIANGULI

Plate 4

THE SPIRAL NEBULA M.74 PISCIUM

Plate 5

THE NEBULA M.76 PERSEI

Plate 6

THE NEBULA H.V. 19 ANDROMEDAE

Plate 7

THE SPIRAL NEBULA M.77 CETI

Plate 8

THE PLEIADES

Plate 9

THE CRAB NEBULA IN TAURUS

Plate 11

CENTRAL PORTION OF THE GREAT NEBULA IN ORION

Plate 12

THE NEBULA H.V. 30, ORIONIS

Plate 13

THE NEBULA H.V. 28 ORIONIS

Plate 14

THE NEBULA M.78 ORIONIS

Plate 15

NEBULA NEAR 15 MONOCEROTIS

Plate 16

NEW NEBULA IN MONOCEROS (ROBERTS)

Plate 17

THE SPIRAL NEBULA H.V.44 CAMELOPARDI

Plate 18

THE NEBULA H.I.200 LEONIS MINORIS

Plate 19

THE SPIRAL NEBULA H.I.205 URSAE MAJORIS

Plate 20

THE SPIRAL NEBULA H.I.56-57 LEONIS

Plate 21

THE SPIRAL NEBULA M 81, URSAE MAJORIS

Plate 22

THE NEBULA H.I.163, SEXTANTIS

Plate 23

THE SPIRAL NEBULA H.I.199, URSAE MAJORIS

Plate 24

THE DOUBLE NEBULA H.II 28-29, LEONIS

Plate 25

THE PLANETARY NEBULA H.IV 27, HYDRAE

Plate 26

THE NEBULA H.V 46, URSAE MAJORIS

Plate 27

THE OWL NEBULA, M 97, URSAE MAJORIS

Plate 28

THE SPIRAL NEBULA M 65, LEONIS

Plate 29

THE SPIRAL NEBULA M 66, LEONIS

Plate 30 A

THE SPIRAL NEBULA H.II, 730, URSAE MAJORIS

Plate 30 B

THE SPIRAL NEBULA H.II, 730, URSAE MAJORIS

Plate 31

THE NEBULA H.V 41, CANUM VENATICORUM

Plate 32

THE SPIRAL NEBULA M 99, COMAE BERENICES

Plate 33

THE SPIRAL NEBULA H.V 43, URSAE MAJORIS

Plate 34

THE SPIRAL NEBULA M 61, VIRGINIS

Plate 35

THE SPIRAL NEBULA M 100, COMAE BERENICES

Plate 36

THE NEBULA H.I 197-198, CANUM VENATICORUM

Plate 37

THE SPIRAL NEBULA M 88, COMAE BERENICES

Plate 38

THE SPIRAL NEBULA H.V 2, VIRGINIS

Plate 39

THE SPIRAL NEBULA H.I 92, COMAE BERENICES

Plate 40

THE NEBULA H.V 24, COMAE BERENICES

Plate 41

THE NEBULA H.V 42, COMAE BERENICES

Plate 42

THE SPIRAL NEBULA H.I 84, COMAE BERENICES

Plate 43

THE SPIRAL NEBULA M 94, CANUM VENATICORUM

Plate 44

THE SPIRAL NEBULA M 94 CANUM VENATICORUM

Plate 45

THE SPIRAL NEBULA M 64, COMAE BERENICES

Plate 46

THE SPIRAL NEBULA M 63, CANUM VENATICORUM

Plate 47

THE SPIRAL NEBULA M 51, CANUM VENATICORUM

Plate 48

THE STAR CLUSTER M 3, CANUM VENATICORUM

Plate 49

THE SPIRAL NEBULA M 101, URSAE MAJORIS

Plate 50

THE DOUBLE NEBULA H.II 751-752, BOOTIS

Plate 51

THE NEBULA H.I 215, DRACONIS

Plate 52

THE STAR CLUSTER M 5, LIBRAE

Plate 53

THE STAR CLUSTER M 13, HERCULIS

Plate 54

THE STAR CLUSTER M 12, OPHIUCHI

Plate 55

THE TRIFID NEBULA, M 20, SAGITTARII

Plate 56

THE NEBULA M 8, SAGITTARII

Plate 57

THE PLANETARY NEBULA H.IV 37, DRACONIS

Plate 58

THE HORSE SHOE OR OMEGA NEBULA M 17, SAGITTARII

Plate 59

THE RING NEBULA, M.57, IN LYRA

Plate 60

THE DUMB-BELL NEBULA IN VULPECULA

Plate 61

THE ANNULAR NEBULA H.IV 13, CYGNI

Plate 62

THE SPIRAL NEBULA H.IV 76, CEPHEI

Plate 63

THE NET-WORK NEBULA IN CYGNUS

Plate 64

THE PLANETARY NEBULA H.IV 1, AQUARII

Plate 65

THE NEBULA H.IV 74, CEPHEI

Plate 66

THE NEBULA H.II 207, PEGASI

Plate 67

THE SPIRAL NEBULA H.I 53, PEGASI

Plate 68

THE SPIRAL NEBULA H.I 55, PEGASI

Plate 69

THE PLANETARY NEBULA H.IV 18, ANDROMEDAE

Plate 70

THE NEBULA H.II 240, PEGASI

Footnotes:

[1] Reprinted from The Astrophysical Journal, 11, 325, 1900.

[2] For a more complete history of this part of the subject, see Dr. Holden’s articles in Pub. Ast. Soc. Pacific, 7, 197 et seq., 1895.

[3] The difficulties here referred to, about which a good deal has been written, seem to have had their origin in the fact that it was impossible, at the time of the preliminary trials, to provide the observer with an assistant, while the Crossley reflector is practically unmanageable by a single person.

[4] Mon. Not. R. A. S., 48, 386.

[5] Kindly lent by the Astronomical Society of the Pacific.

[6] Mem. R. A. S., 46, 173.

[7] Mon. Not. R. A. S., 48, 280, 1888.

[8] Mon. Not. R. A. S., 49, 297. The construction here described is not followed exactly in the Crossley apparatus. The guiding eyepiece slides freely when not held by a clamp. Pin-holes for preventing fogging are unnecessary when red light is used.

[9] It so happens that the tension of the vertical thread is such that it begins to slacken when the temperature falls to within about 2° of the dew point. The thread thus forms an excellent hygrometer, which is constantly under the eye of the observer. When the thread becomes slack, it is time to cover the mirrors.

[10] Mon. Not. R. A. S., 48, 352.

[11] The following list includes all papers of interest:

“Photographic Observations of Comet I, 1898 (Brooks), made with the Crossley Reflector of the Lick Observatory.” A. J. No. 451, 19, 151; see also Ap. J., 8, 287.

“The Small Bright Nebula near Merope,” Pub. A. S. P., 10, 245.

“On Some Photographs of the Great Nebula in Orion, taken by means of the Less Refrangible Rays in its Spectrum,” Ap. J., 9, 133. See also Pub. A. S. P., 11, 70; Ap. J., 10, 167; A. N., 3601.

“Small Nebulæ discovered with the Crossley Reflector of the Lick Observatory,” Mon. Not. R. A. S., 59, 537.

“The Ring Nebula in Lyra,” Ap. J., 10, 193.

“The Annular Nebula H. IV. 13 in Cygnus,” Ap. J., 10, 266; see also Pub. A. S. P., 11, 177.

“On the Predominance of Spiral Forms among the Nebulæ,” A. N., 3601.

“The Distribution of Stars in the Cluster Messier 13 in Hercules” (by H. K. Palmer), Ap. J., 10, 246.

“The Photographic Efficiency of the Crossley Reflector,” Pub. A. S. P., 11, 199; Observatory, 22, 437.

“New Nebulæ discovered photographically with the Crossley Reflector of the Lick Observatory,” Mon. Not. R. A. S., 60, 128.

“The Spiral Nebula, H. I., 55 Pegasi,” Ap. J., 11, 1.

“Photographic Observations of Hind’s Variable Nebula in Taurus, made with the Crossley Reflector of the Lick Observatory,” Mon. Not. R. A. S., 60, 424.

“Use of the Crossley Reflector for Photographic Measurements of Position,” Pub. A. S. P., 12, 73.

“Discovery and Photographic Observations of a New Asteroid 1899 FD.,” A. N., 3635.

“Elements of Asteroid 1899 FD.” (by H. K. Palmer), A. N. 3635.

[12] Footnote added in 1908: This concluding paragraph, retained in the present publication for completeness, loses point in some particulars, because the photogravure referred to is not reproduced here. The heliogravure reproduction of the Trifid nebula is No. 55.

[13] Since then a photograph by Dr. Roberts has appeared in Knowledge, 23, 35, February, 1900.

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Table of Contents

PREFACE.

TABLE OF CONTENTS.

THE CROSSLEY REFLECTOR OF THE LICK OBSERVATORY.[1]

LIST OF ILLUSTRATIONS.

THE FULL PROJECT GUTENBERG™ LICENSE