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[M 42]

Messier 42

Observations and Descriptions

Probably discovered in 1610 by Nicholas-Claude Fabri de Peiresc.
Independently discovered by Cysatus in 1611.
Independently rediscovered by Hodierna before 1654.
Independently rediscovered by Huygens in 1656.

Messier: M42.
March 4, 1769. 42. 5h 23m 59s (80d 59' 40") -5d 34' 06"
Position of the beautiful nebula in the sword of Orion, around the star Theta which it contains [together] with three other smaller stars which one cannot see but with good instruments. Messier has entered into the great details in this great nebula; he has created a drawing, made with the greatest care, which one can see in the Memoirs of the Academy for 1771, plate VIII. It was Huygens who discovered it in 1656: it has been observed since by many astronomers. Reported in the English Atlas.

[Mem. Acad. for 1771, p. 450-451 (first Messier catalog)]
I have examined a large number of times the nebula in the sword of Orion, which Huygens discovered in the year 1656, & of which he has given a drawing in the work which he has published in 1659, under the title Systema Saturnium [Saturnian System]. It has been observed since by different Astronomers. M. Derham, in a Memoir printed in the Philosophical Transactions, no. 428, page 70, speaks of that nebula which he has examined with a reflecting telescope of 8 feet [FL]. Here is the translation [actually here, the text] of what he has reported in this Memoir. "[But] only that in Orion, hath some Stars in it, visible only with the Telescope, but by no Means sufficient to cause the Light of the Nebulose there. But by these Stars it was, that I first perceived the Distance of the Nebulosae to be greater than that of the Fix'd Stars, and put me upon enquiring into the rest of them. Every one of which I could very visibly, and plainly discern, to be at immense Distance beyond the Fix'd Stars near them, whether visible to the naked Eye, or Telescopick only; yea, they seemed to be as far beyond the Fix'd Stars, as any of those Stars are from Earth." M. le Gentil also examined this nebula with ordinary refractors of 8, of 15 & of 18 feet [focal] length; as well as a Gregorian telescope of 6 feet, which belongs to Mr. Pingré. He has published his observations in a Memoir which can be found printed in the Volumes of the Academy, year 1759, page 453. There is a joint of the drawings which he had made of it at that time, as well as those of Huygens & of Picard; these drawings differ from each other, so that one may suspect that this nebula is subject to sort of variations. Here is what I have reported about that nebula in the Journal of my Observations. On March 4, 1769, the sky was perfectly serene, Orion was going to pass the meridian, I have directed to the nebula of this constellation a Gregorian telescope of 30 pouces focal length, which magnified 104 times; one saw it perfectly well, & I drawed the extension of the nebula, which I compared consequently to the drawings which M. le Gentil has given of it, I found some differences. This nebula contains eleven stars; there are four near its middle, of different magnitudes & strongly compressed to each other; they are of an extraordinary brilliance: here is the position of the brightest of the four stars, which Flamsteed, in his catalog, designated by the greek letter Theta, of fourth magnitude, 80d 59' 40" in right ascension, & 5d 34' 6" in southern declination: this position has been deduced from that which Flamsteed has given in his catalog.
[p. 458] 1769.Mar. 4. RA: 80.59.40, Dec: 5.34. 6.A. Position of the star Theta in the Sword of Orion, which is situatedin the middle of the nebula in that constellation.
[On p. 458-561 of the 1771 memoir follows a Drawing and Description of the Orion Nebula M42/43]

[1609] I have added eighty other stars recently discovered in the vicinity [of Orion's sword and belt]
He did not notice the nebula.

[Feb. 4, 1617] Galileo created a drawing, again not noting the nebula, but showing the three brightest stars of the Trapezium cluster: Theta1 Ori C, A, and D.

[Nov. 26, 1610] In the middle of Orion .... Composed of two stars, there is a nebula ..
Peiresc's discovery is reported by G. Bigourdan in Comptus Rendus, Vol. 162 (Jan-Jun 1916), p. 489-490.

[1611] (compared it to the comet of 1618, published in 1619).
"Caeterum huic phaenomeno similis stellarum congeries est in firmamento ad ultimam stellam Gladii Orionis, ibi enim cernere est (per Tubum) cougestas itidem aliquot stellas angustissimo spatio et circumcirca interque ipsas stellulas instar albae nubis candidum lumen affesum." [This phenomenon is similar to the congeries of stars that is in the firmament towards the last star of the Sword of Orion; there truely is seen (by telescope) a congestion of stars in a narrow space and all round and between those stars light diffuses like a shining white cloud.]
This independent re-discovery was reported by Rudolf Wolf in Astronomische Nachrichten, Vol. 38, No. 895 (1854), col. 109.

Hodierna: Ha. I.5
[1654] [5.] The fifth [shines] in the sword of Orion and includes 22 stars as one can see with the telescope. But this Luminosa is more admirable because of some unresolvable luminosity in whose middle can be seen three stars [see figure].
[The three stars mentioned and depicted in the nebula are probably Theta1, Theta2A, and Theta2B. They are very probably not the three brightest Trapezium stars, as had been suspected previously. - hf]

[1756] There is one phenomenon among the fixed stars worthy of mention, which as fas as I know, has hitherto been noticed by no one and indeed, cannot be well observed except with large telescopes. In the sword of Orion are three stars quite close together. In 1656 as I changed viewing the middle one of these with the telescope [a 23-foot FL refractor], twelve showed themselves - not an uncommon circumstance, Three of these almost touched each other and, with four others, shone through a nebula so that the space around them seemed brighter than the rest of the heavens which was entirely clear and appeared quite black, the effect being that of an opening in the sky through which a brighter region was visible.

In 1673, Picard discovered the fourth Trapezium star.

In 1684, Huygens also found the fourth star with a 34-foot FL refractor. In 1695, he sketched the nebula with the "trapezium."

Halley (1716): No. 1, Nebula in Orion.
[in Phil. Trans. XXIX, 390 (1716)] The first and most considerable is that in the Middle of Orion's Sword, marked with Theta by Bayer in his Uranometria, as a single Star of third Magnitude; and is so accounted by Ptolemy, Tycho Brahe and Hevelius: but is in reality two very contiguous Stars environed with a very large transparent bright Spot, through which they appear with several others. These are curiously described by Hugenius [Christiaan Huygens] in his Systema Saturnium pag. 8, who there calls this brightness Portentum, cui certe simile aliud nusquam apud reliquas Fixas potuit animadvertere [a wonderful object, which is certainly unique among the fixed stars]: affirming that he found it by chance in the Year 1656. The Middle of this is at present at [Gemini] 19 deg 00, with South lat. 28 deg 3/4.

De Chéseaux: De Ch. No. 16.
That [nebula] in Orion, discovered by Mr. Huygens.

Le Gentil:
(March 10, 1758) It appeared to have the shape of the open jaws of some animal. I observed toward the west, an extension of light forming a rectangle: this light is very diffuse. The three stars in a straight line in the "lower jaw" appear completely detached from the nebula.

(April 3, 1758) The four stars in the center appear extraordinarily brilliant.

Bode: Bode 10.
[This] Is the most remarkable nebula in the sky, 6' large.
The location of the remarkable nebulous region at the sword of Orion is given very indefinite in most of the sky charts and astronomical scripts known to us. But the 15th figure depicts its actual location correctly. The star Theta, which is the one in the middleat the sword, and was described as double by Flamsteed, is situated in the middle of this nebula. 1. Theta appears fourfold in good telescopes, as it has 3 small stars close to it to the east; 2. Theta is close to the east near the previous one and has two small stars east and near it. These indicated seven stars are all involved ina vivid nebula or luminous glow, which appears inclined from evening to morning, in an elongated and curved tongue-shaped figure. Close to the north of this nebula, a small star appears which has something nebulous around it (M43). About 32' north of 1 and 2 Theta are the stars 1 and 2 c Ori; and about equally south of them is the star Jota after Flamsteed.

Bode (1782):
[From: Vorstellung der Gestirne auf XXXIV Kupfertafeln (Introduction to the Stars on 34 Copper Plates), 1782. Here p. 31, plate 24]
Ori 83, after Messier. RA: 81:06 [05:24.4], Dec: -05:32. The most remarkable nebulous patch in the sky in which there are stars 1.Theta, 2.Theta.
In this nebula & near it are, among others, the stars which can be found in plate 30, Fig. 5.
[The position is that given for 1.Theta. 2.Theta is given at RA=81:07 (05:24.0), Dec=-05:33]

[P. 38, plate XXX (30)]
Fig. 4. The region around the nebula at 1.2 Theta [Theta 1 and Theta 2] in the sword of Orion, with many small stars hanging around there with their incidental positions. The stars 1. 2. c. show up north and Iota south of this nebula.

Fig. 5. Is the previous remarkable nebula in Orion, as it shows up in good telescopes with many small stars standing closest to it after the observation of Mr. Messier. The star 1 Theta after Flamsteed is in the middle of this nebula, and composed of four stars; however, for the discovery of the smallest of them, very good telescopes are required; 2 Theta follows closely eastward and has two smaller stars in a line with it, which are situated together with it in the nebula or luminous space. To the northeast, beyond the nebulous place, there is still another single star, which has some nebulosity around it [M43]. The difference in right Ascension and Declination from 1 Theta of all stars situated near and in the nebula is recognizable from the figure.

William Herschel
[1811: PT Vol. 1811, p. 226-336; here p. 278-80]
3. Of Nebulosities joined to Nebulae.
The nature of diffused nebulosities is such that we often see it joined to real nebulae; for instance of this kind we have the following fourteen objects [including M42] ..
No. 42 of the Connoissance is the great nebula in the constellation Orion discovered by Huygens. This highly interesting object engaged my attention already in the beginning of the year 1774, when viewing it with a Newtonian reflector I made a drawing of it, to which I shall have occasion hereafter to refer; and having from time to time reviewed it with my large instruments, it may easily be supposed that it was the very first object to which, in February 1787, I directed my forty feet telescope. The superior light of this instrument shewed it of such a magnitude and brilliancy that, judging from these circumstances, we can hardly have a doubt of its being the nearest of all the nebulae in the heavens, and as such will afford us many valuable informations. I shall however now only notice that I have placed it in the present order because it connects in one object the brightest and faintest of all nebulosities, and thereby enables us to draw several conclusions from its various appearances.
The first is that the extensive diffused nebulosities contained in the objects of the preceding articles are of the same nature with the nebulosity in this great nebula; for when we pursue it in its extensive course it assumes precisely the same appearance as the before-mentioned diffused nebulosities.
The second consequence we may draw from the circumstance of its containing both the brightest and the faintest nebulosity joined in one object is a confirmation of an opinion already conceived in the second article [on "extensive diffused nebulosities"], namely, that the range of the visibility of nebulous matter is what may be called very limited. The depth of the nebulae may undoubtedly be exceedingly great, but when we consider that its greatest brightness does not equal that of small telescopic stars, as may be seen by comparing four of them situated within the inclosed darkness of the nebula, and several within its brightest appearance, with the intensity of the nebulous light; it cannot be expected that such nebulosities will remain visible when exceedingly farther from us than this prime nebula: the ratio of the known decrease of light will not admit a great range of visibility within the narrow limits whereby this shining substance can affect the eye.
From this argument a secondary conclusion may be drawn, which adds to what has already been said in the foregoing article, namely, that if our best telescopes cannot be expected to reach the nebulous matter, which by analogy we may suppose to be lodged among the very small stars plainly to be seen by them; the actual quantity of its diffusion may still farther exceed even the vast abundance of it already proved to exist. A nebulous matter, diffused in such exuberance throughout the regions of space, must surely draw our attention to the purpose for which it may probably exist; and it must be the business of a critical inquirer to attend to all the appearances under which it will be exposed to his view in the following observations.

[p. 320-325]
31. Of the Distance of the Nebula in the Constellation Orion
In my 3rd article [above] I concluded, from the appearance of the great nebula in Orion, that the range of the visibility of the diffused nebulous matter cannot be great, because we may there see in one and the same object, both the brightest and faintest appearance of nebulosities that can be seen any where. It will therefore be a case of some interest, if we can form any conception of the place among the fixed stars to which we ought to refer the situation of this nebula; and this I believe my observation of it will enable us to determine pretty nearly.
In the year 1774, the 4th of March, I observed the nebulous star, which is the 43d of the Connoissance des Temps [M43], and is not many minutes north of the great nebula; but at the same time I also took notice of two similar, but much smaller nebulous stars; one on each side of the large one, and at nearly equal distance from it. Fig. 37 is a copy of the drawing which was made at the time of observation.
In 1783, I reexamined the nebulous star, and found it to be faintly surrounded with a circular glory of whitish nebulosity, faintly joined to the great nebula.
About the latter end of the same year I remarked that it was not equally surrounded, but most nebulous toware the south.
In 1784 I began to entertain an opinion that the star was not connected with the nebulosity of the great nebula in Orion, but was one of those which are scattered over that part of the heavens.
In 1801, 1806, and 1810 this opinion was fully confirmed, by the gradual change which happened in the great nebula, to which the nebulosity surrounding this star belongs. For the intensity of the light about the nebulous star had by this time been considerably reduced, by attenuation or dissipation of nebulous matter [this observation was probably an illusion]; and it seemed now to be pretty evident that the star is far behind the nebulous matter, and that consequently its light in passing through it is scattered and deflected, so as to produce the appearance of a nebulous star [these speculations are not correct]. A similar phenomenon may be seen whenever a planet or a star of the 1st or 2nd magnitude happens to be involved in haziness; for a diffused circular light will then be seen, to which, but in a much inferior degree, that which surrounds this nebulous star bears a great resemblance.
When I reviewed this interesting object in December 1810, I directed my attention particularly to the two small nebulous stars, by sides of the large one, and found that they were perfectly free from every nebulous appearance; which confirmed not only my former surmise of the great attenuation of the nebulosity, but also proved that their former nebulous appearance had been entirely the effect of the passage of their feeble light through the nebulous matter spread out before them [actually, these nebulous stars had probably been illusions].
The 19th of January 1811, I had another critical examination of the same object in a very clear view through the 40-feet telescope; but notwithstanding the superior light of this instrument, I could not perceive any remains of nebulosity about the two small stars, which were perfectly clear, and in the same situation, where about thirty-seven years before I had seen them involved in nebulosity.
If then the light of these three stars is thus proved to have undergone a visible modification in its passage through the nebulous matter, it follows that its situation among the stars is less distant than the largest of the three, which I suppose to be of the 8th or 9th magnitude. The farthest distance therefore, at which we can place the faintest part of the great nebula in Orion, to which the nebulosity surrounding the star belongs, cannot well exceed the region of the stars of the 7th or 8th magnitude, but may be much nearer; perhaps it may amount to the distance of the stars of the 3rd or 2nd order; and consequently the most luminous appearance of this nebula must be supposed to be still nearer to us. From the very considerable changes I have observed in the arrangement of its nebulosity, as well as from its great extent, this inference seems to have support from observation; for in very distant objects we cannot so easily perceive changes as in near ones, on account of the smaller angles which both the objects and its changes subtend at the eye. The following memorandum was made when I viewed it in 1774: "its shape is not like that which Dr. Smith has delineated in his optics, though somewhat resembling it, being nearly as in fig. 37: from this we may infer that there are undoubtedly changes among the regions of the fixed stars; and perhaps from a careful observation of this lucid spot, something may be concluded concering the nature of it."
In January 1783, the nebulous appearance differed much from what it was in 1780, and in September it had again undergone a change in shape suince January [again, these presumed changes are probably illusions caused from different viewing conditions].
March 13, 1811. With a view to ascertain such obvious alterations in the disposition of the nebulous matter as may be depended on, I selected a telescope that had the same light and power which thirty-seven years ago I used, when I made the above-mentioned drawing; and the relative situation of the stars remaining as before, I found that the arrangement of the nebulosity differs considerably. The northern branch N still remains nearly parallel to the direction of the stars a b ; but the southern branch S is no longer extended towards the star d; its direction is now towards e, which is very faintly involved in it. The figure of the branch is also different; the parallel P F of the three stars being more advanced towards the following side than it was formerly.
I compared also the present appearance of this nebula with the delineation which Huygens has given in his Systema Saturnium, page 8, of which fig. 38 is a copy. The twelve stars which he has marked are sufficient to point out the arrangement of the nebulous matter at the time of his observation. By their situation we find that the nebula had no southern branch, nor indeed any to the north, unless we call the nebulosity in the direction of the parallel a branch; but then this branch is not parallel to the line drawn from a to the star b; moreover the star f is now involved in faint nebulosity, which also reaches nearly up to g, and quite incloses h. The star b which is now nebulous, is represented as perfectly out of all nebulosity, and can hardly be supposed to have been affected when Huygens observed it. [The "changes" assumed here are actually effects of Huygens' inferior instrumentation]

[Unpublished Observations of Messier's Nebulae and Clusters. Scientific Papers, Vol. 2, p. 654-657]
M.42 and M.43 [NGC 1976 and NGC 1982, Great Nebula in Orion]
(*) Dreyer's note: The following observations have already appeared in print in Holden's "Monograph of the Central Parts of the Nebula of Orion," Washington Observations for 1878, Appendix I., but only copied from Caroline Herschel's transcript and not from the original Journal. They are here given in full on account of the special interest attaching this object. The rough pen-and-ink sketch made on March 4, 1774, was copied on the plate belonging to the paper of 1811, see Pl. III, fig 37; compare p. 465 [of SP2].
1774, March 1. Observed the Lucid Spot in Orion's sword belt; but the air not being very clear, it appeared not distinct.
1774, March 4. Saw the lucid spot in Orion's sword thro' a 5 1/2 foot reflector; its shape was not as Dr Smith has delineated in his Optics; tho' something resembling it, being as follows [Plate III, fig. 37]. From this we may infer that there are undoubtedly changes among the fixt stars, and perhaps from a careful observation of this spot something might be concluded concerning the nature of it.
1776, Nov. 11. The lucid spot in Orion, about 10 o'clock just rising at 5d high [see diagram, 1779 Oct. 7]. The greatest glare immediately about the 3 small stars 2, 5, 6 in the corner, the middle whereof is one or two magnitudes larger than the other two. The three succeeding stars 1, 3, 4 were almost on the upper side of this figure free from any glare, and there was a total darkness in the corner by the 3 before mentioned close in the corner. There was a very faint glimmering of a seventh star which I have marked but which must be several magnitudes less than the other 6. The two Nos. 1 2 were of one size, the two 3 4 next, the two 5 6 considerably less and 7 very much less again, almost invisible. The whole was exceedingly distinct. Instrument 10 ft. reflector, power 120. There was also an 8th star visible near the 6th with the same small size with the 7th or rather less.
1778, Jan. 25. Die Nebula im Orion [sic!] from 10 to 12 o'clock. In the east the lucid ray seems to make an equilateral (*) triangle with the stars 1 & 3 where one is the vertex and seems from the base to go on in the direction of 1 3 4 rather approaching to 4 and afterwards bend round 4 in an angle of about 110 to 120 degrees to the east. From 2 to 7 the lucid part is concave, the concave part turned towards 3, and goes to the northwest about 3/4 of the distance from 2 to 7; it turns from thence to west in angle of about 75 or 70.

(*) [Over this word ("equilateral") is written in pencil "isosceles." - Ed. (Dreyer)]
1778, Jan. 26. From 10 to 12, observation of the Nebula.
6.2.1 make a straight line.
6.8.7 make a straight line.
The lines 2 . 5 and 1 . 3 . 4 diverge; 5 a little larger than 6; 4, 5, 8 make a straight line.
1778, Feb. 7. 11h 30'. I observed the Lucid Spot again and saw all 4 stars very well, and their place agreed with the observation of Jan. 25.
1778, Feb. 25. I observed the Lucid Spot in Orion when on and near the meridian and found everything in regard to the situation of the 4 little stars to agree with the observation of Jan. 25.
1778, Dec. 15. Lucid Spot in Orion's sword handle.
6 . 8 . 7 make a straight line.
6 . 2 . 1 make a straight line.
4 . 5 . 8 make a straight line.
The lines 2 . 5 and 1 . 3 . 4 diverge. This agrees with the observation of Jan. 26. But there is a visible alternation in the figure og the lucid part.
1779, Oct 7. Theta Orionis. The line 6 . 2 . 1 is a little convex towards 5, when that line is taken into the middle of the field; this I mention, as it is possible there might be a little curvature arising from the spherical figure of the eyepiece, tho' I believe there is not. If a line be drawn from 6 to 7, the star 8 stands outward I suppose no less than 15deg, so that 6 . 8 . 7 is concave towards the side 1 . 3 . 4. The line 4 . 5 . 8 I cannot very well compare, being rather too far distant by the power I now use, but I believe it is not far from a right line. I see a 9th star which is marked in annexed figure, where however not the least exactness is intended. Altitude about 26 degrees. 14h 10'. The figure of the lucid part is much altered.
[With this observation is a sketch of the stars 1..9; Trapezium is 2,5,6,8]
1779, Dec. 5. 6 . 2 . 1 concave, the concave part turned to the south. 8 . 6 . 7 still makes an angle at 6, tho' very small. I see the 9th star mentioned [Oct. 7].
1780, Jan 22. 10h 30'. The stars 6 . 2 . 1 instead of seeming concave towards the north appear convex. This may however be a deception as the star 2 is the largest, and since there is pretty strong aberration on account of a fog, its diameter is more increased than that of 6 and consequently may give the balance towards the north.
1780, Feb. 19. Exactly as described [Oct. 7, 1779].
1780, Feb 28. The two stars 6 . 2 measure 12".812; the measure is pretty narrow, but I believe true enough. The two stars 2 . 5 measure 14".271, this is also a pretty narrow but just measure. The two stars 6 . 8 measure about 9".062, but this is doubtful on account of the obscurity of the stars 8, which is hardly perceptible when the field of view is illuminated properly so as to make the parallel hair very distinct. The two stars 5 . 8 measure 20".521. This is also doubtful on the same account.
1780, Oct. 10. Theta. The upper stars concave by the hair, the spot extremely fine. The 4 stars are all full and well defined.
1780, Nov. 24. 12h. The Nebula in Orion is very fine indeed. I perceive not the least alteration.
1783, Jan. 31. Theta Orionis. The Nebula quite different from what it was last year. The 9th star very strong.
1783, Sept. 20. The Neb. in Orion has evidently changed its shape since I saw it last. The star under the nebula is nebulous. 20 ft., 200.
1783, Sept. 28. Surprising changes in the Nebula Orionis.
1783, Nov. 3. The Nebula in Orion is beautiful, and I see several circumstances which I never observed with other instruments, viz. just close to the four stars it is totally black for a very short space, a few seconds. Below, in the open black part is a small distinct nebula of an extended shape. (*) The eastern branch of the great nebula extends very far; it passes between two very small stars and runson so far as to meet a pretty bright star. The nebulous star below the nebula is not equally surrounded, but most towards the south; on the north of this lesser nebula it is joined by one still fainter, which makes a rectangular corner by its meeting the small nebula.
(*) [This is III.1, an appendage to Messier 43. - Ed. (Dreyer)]
1784, Oct. 16 (Sweep 296). The beginning of the neb., 5 Monocerotis p. 41' 6" n 0d 43'. My small neb. is just under the south following corner of the great one. The 43rd [M43] is not a nebulous star, the star not being at all in the center of it; my little one makes a part of it. It is altogether the most wonderful object in the heavens.
1784, Dec. 20. The nebula in Orion as before described, but the moon being bright it seems to extend hardly 3/4 of a degree.
1785, Feb. 13. With the new 10 feet reflector I examined the neb. in Orion, and with long attention could just perceive my small faint nebula in the dark part of the great nebula.
1785, Oct. 5 (Sweep 458). The nebula in Orion. A wonderful phenomenon. One of the clearest nights I ever had.
1786, Nov. 28 (Sweep 640). The nebula in Orion which I saw by the front-view was so glaring and beautiful that I could not think of taking any place of its extent.
1799, Dec. 30, Review.(*) No. 43 of the Connoiss. [M43] is not visible in the finder but is the star north of No. 42. 10 feet, 300. The nebulosity about the star is not central and belongs probably to the rest of the nebulosity, the star being one of the scattered ones.
(*) [This and the following observations were not taken in the course of sweeps. - Ed. (Dreyer)]
1801, Jan. 14, Review. Large X [10] feet telescope, power 120. As before described. The nebulosity of the 43rd [M43] does not seem to belong to the star.
1806, Feb. 11, Review. Large 10 feet. The 4 stars are completely in the nebulosity. The 3 stars are entirely out of it with 270. With the double eyeglass, appearances are very different.
1810, Feb. 4, Review. 10 feet. The nebulosity is entirely of the milky kind and extends a great way. The 43rd [M43] is not a nebulous star, but a star happens to be situated in a place where some of the milky nebulosity of the great nebula happens to be. 1810, Dec. 31, Review. 10 feet, double eyepiece. The 4 stars are within the nebulosity. The star No. 7 (see the figure of Oct. 7, 1779) is upon the borders of the dark vacancy. I see No. 9 very well. The little star between 3 and 4 is still within very faint nebulosity. The nebulosity reaches beyond 4, as far as from 1 to 4 nearly. It touches a very small star and from that star goes on to two very bright ones, in the direction from the small star to the preceding one of the two. The black space near the four stars is much contracted. The nebulosity from 1 to 4 is concave, the concavity being to the following side. The parallel is nearly in the line 1 . 3 . 4. I can see eight different condensations notwithstanding the moon is very bright. The nebulous star is pretty equally involved, it has the appearance of a star shining through a very faint mist. The star is little larger than 4. The concavity from 2 to 7 goes beyond 7.
1811, Jan. 19, Review. 10 feet. Two of the four stars are within the nebulosity. No. 7 is very near the borders of the black. The little star between and following 3 and 4 is still within very faint nebulosity. The nebulosity reaches beyond 4 rather farther than form 1 to 4.
X feet. I perceive 7 or 8 different condensations. The place near the 4 stars is much contracted. The nebulous stars is exactly what we might expect to see if a star were to shine through whitish nebulosity.
40 feet. 5h 16' B. affected.(+)
[5h] 17 B. much affected.
[5h] 22 The 4 stars are entirely involved in nebulosity. The 7th and 9th stars are very bright.In the brightest part are four places brighter than the rest. I see the small detached nebula, it is extremely faint. It is between the corner and a small star. The star called nebulous is within a nebulosity nearly detached; but the small star marked nebulous in the figure of the 4th March 1774 (+) are free from nebulosity.There is a very small, nearly detached, nebulosity north of the nebulous star. The nebulous star has some resemblance tp a star shining through a very thin mist.
1811, Mar. 13, Review.(+) 7 feet, double eyepiece. The following or rather the south branch (for I find the parallel is nearly in the line 1 . 3 . 4) goes towards the preceding star e of the two large stars d e, or rather little preceding it, but it partly includes the star e and makes it appear a little nebulous. The light about the nebulous b is a little denser nearer the star than at a distance. A line from 5 through 7 goes to b or rather a little south of it; and 7 is about a 1/4 of the distance towards b. The star south of 3 and 4 makes an equilateral triangle with them. The two large stars d and e are parallel to 1 . 3 . 4 nearly. A line from the four stars parallel to 1 . 3 . 4 passes a little south of the small formerly nebulous star c. There are many other stars connected with the nebula which I do not notice.
1811, Mar. 15, Review. 7 feet, double eyepiece. The northern branch is parallel to the stars a b. The nebulosity reaches nearly up to the stars g h. A very faint nebulosity still joins the star b to the northern branch, but b is more nebulous than the intermediate nebulosity. The southern nebulosity goes towards the star e, and some part of the very faint nebulosity incloses the star.
1811, March 16, Review. 10 feet reflector, power 100. The stars 1.3 are in the parallel; 4 is a very little south of their parallel. The nebulosity about b is brightest about the star.
(+) [Compare Plate III fig. 37 and p. 489 (of SP2). - Ed. (Dreyer)]

John Herschel (1833): h 360.
h 360 = Theta Orionis.
Various sweeps.
RA 5h 26m 55s +/-, NPD 95d 30' 30" (1830.0) [Right Ascension and North Polar Distance]
Observed in sweeps 16, 38, 40, 110, 172, 173, 232 .. 235, 309, 318, &c. See description and figure in Mem. Astr. Soc. 1826.
[The sweeps listed correspond to the dates: 16 - February 13, 1826; 38 - December 28, 1826; 40 - January 2, 1827; 110 - December 16, 1827; 172 - September 5, 1828; 173 - September 7?, 1828; 232 - February 10, 1830; 233 - February 11, 1830; 234 - February 19, 1830; 235 - February 20, 1830; 309 - December 13, 1830; 318 - January 8, 1831]

Smyth: CCXVI [216]. Theta1 Ori [Trapezium and M42].
CCXVI. Theta1 Orionis.
AR 5h 27m 25s, Dec S 5d 30'.0
Mean Epoch of Observation: 1834.07 [January 1834]
  Position AB 311d.1 (w 8)   Distance 13".0 (w 6)
  -------- AC  60d.2 (w 8)   -------- 13".5 (w 6)
  -------- AD 344d.7 (w 8)   -------- 16".7 (w 6)
  -------- BE 350d.0 (w 8)   --------  5".0 (w 6)
[with drawing]
A multiple star, the beautiful trapezium in the "Fish's mouth" of the vast nebula in the middle of Orion's sword-scabbard. A 6 [mag], pale white; B 7, faint lilac; C 7 1/2, garnet; D 8, reddish; and E 15, blue. This was entered 1 H. III. [M43], in November, 1776, and had the honour of being the object to which the grand forty-foot reflector was first directed, in February, 1787, under the designation "quadruple." As a trapezium it was gazed at, measured, and delineated, for upwards of fifty years, when Struve announced it "quintuplex," by the addition of the little star E. Now when we consider the eye of WH [William Herschel], the measures of South, and the rigorous examination of JH [John Herschel], this little companion must be looked upon as variable; indeed nothing can exceed the confidence with which H. [John Herschel] assured me, of its not being visible when he made the beautiful drawing of 1824, confirmed by himself and Mr. Ramage on the 3rd of March, 1826: and yet in 1828 it was not to be overlooked but by wilful inattention. Mr. Dawes afterwards saw it well with his five-foot telescope. The best measures for comparison with my epoch, are those of Struve and South; and by adjusting the latter's uncials and quadrants, they will stand thus:
       South 1824.50                         Struve 1836.15
  AB  Pos. 310d 48'  Dist. 13".453      Pos. 311d 14'  Dist. 12".983
  AC        60d 04'        13".582            60d 07'        13".467
  AD       345d 03'        16".685           342d 10'        16".780
  BE          (not seen)                     353d 42'         3".860 (1832.53)
Ptolemy, Tycho Brahé, and Hevelius, ranked Theta of the 3rd magnitude, as did Bayer in his Uranometria, all evidently supposing the two contiguous stars and the bright spot constituted a single star. The effulgent nebula in which it is placed, familiarly called the Fish's head, with its streaming appendages, certainly has an irregular resemblance to the head of some monster of the polyneme genus. Its brilliancy is not equal throughout, but the glare og the brighter parts gives intensity to the darkness which they bound, and excites a sensation of looking through it into the luminous regions of illimate space, a sensation not entirely owing to any optical illusion of contrast. [..]

John Herschel (1847)
[Plate VIII, Fig 1]

John Herschel, General Catalogue: GC 1179.
GC 1179 = h 360 = M42 = Theta1 Orionis.
RA 5h 28m 24.0s, NPD 95d 29' 10.9" (1860.0) [Right Ascension and North Polar Distance]
!!!; Theta1 Ori & the great neb
Magnificient, Theta1 Orionis & the Great Nebula. Monographingly observed by W. & J. Herschel.
Remark: GC 1179 = h 360. 3.3 s added to h.'s [JH's] P.D. to bring it to the place in B.A.C.
Figures in: C.G.H. [Results of astronomical observations at the Cape of Good Hope, JH 1847], plate viii, fig. 1; B.A.A. [Bond's Memoirs in vol. iii NS of the Transactions of the American Academy of Arts and Sciences], opp. p. 96. Lass. [Lassell's Memoirs, vol. xxiii of the Transactions of the RAS], plate i, fig. 1; (*)
(*) No. 1179 = h. 360. Other figures of the great nebula in Orion will be found in Huygens's Systema Saturnium, 1659; ditto, copied by Le Gentil in Mém. Acad. Sci. Par. 1759, pl. 21, fig. 1; Le Gentil's own figure in do. do. fig. 2; by Picard, do. do. fig. 5, another by Le Gentil, do. do. fig 6. See also: -
Mairan, "Sur la Lumière Zodiacale", copied in Lalande's 'Astronomy.' These older representations, however, are mere curiosities, and present no points to exact resemblence.
Messier, Hist. de l'Acad. Sci. Par., 1771, p. 435...461. Plate 8 is a careful and (for the time) elaborate figure.
J.F.W. Herschel, Mem. Astron. Soc. ii, 1826.
De Vico, Memoria intorno ad alcune osservazione fatte nel Collegio Romano nel corrente anno 1838, nebulosa d'Orione osservata al Telescopio di Cauchoix. 1839.
Bond. A very fine engraving. Not yet published.

[On the Spectrum of the Great Nebula in the Sword-handle of Orion. Phil. Trans. Roy. Soc., Vol. 155 (1865), p. 39-42; here p. 40-41]
[..] I then observed the Great Nebula in the Sword-handle of Orion. [..]
The light from the brightest parts of the nebula near the trapezium was resolved by the prisms into three bright lines, in all respects similar to those of the gaseous nebulae, and which are described in my former paper.
These three lines, indicative of gaseity, appeared (when the slit of the apparatus was made narrow) very sharply defined and free from nebulosity; the intervals between the lines were quite dark.
When either of the four stars Alpha, Beta, Gamma, Delta Trapezii was brought upon the slit, a continous spectrum of considerable brightness, and nearly linear (the cylindrical lens of the apparatus having been removed), was seen, together with the bright lines of the nebula, which were of considerable length, corresponding to the length of the slit. The fifth star Gamma' and the sixth Alpha' are seen in the telescope, but the spectra of these are too faint for observation.

Dreyer (1877)
GC 1179, h 360 [M 42]. The following monographs have appeared since 1864: (*) Two old drawings of the Neb. in Orion (not mentioned by h.) are to be found in Rozier's Journal de Physique, vol. 22, 1779 (by Le Fevre de l'Oratoire), and in Schröter's "Aphroditographische Fragmente," Helmstedt, 1796, Plate II. Both these drawings are not without value.

Vol. VIII of the Annals of the Observatory of Harvard College, which was received at Birr Castle in the summer 1877, contains lithographs from drawings by Mr. Touvelot of the following Nebulae: GC 116 [M 31] (Pl. 33), 1179 [M 42] (Pl. 24, Woodbury type), 4230 [M 13] and 4294 [M92] (Pl. 25), 4355 [M20] (Pl. 32), 4447 [M57] (Pl. 34), 4532 [M27] (Pl. 35).

Dreyer: NGC 1976.
NGC 1976 = GC 1179 = h 360; Cysat, M 42.
RA 5h 28m 24s, NPD 95d 29.2' (1860.0) [Right Ascension and North Polar Distance]
!!! Theta1 Ori and the great neb; = M42
Magnificient, Theta1 Orionis and the Great Nebula.
Remark: Figures (together with M43) in J. Herschel [Mem. R.A.S. ii]; C.G.H. [JH 1847], plate VIII, fig 1; Lam. [Lamont, Ueber die Nebelflecken, Munich, 1837], fig. 11; De Vico [Mem. Oss. d. Coll. Rom. 1839], plate I, II; Bond [W.C. and G.P. Bond, Transactions of American Academy of Arts and Sciences, N.S. vol. iii], p. 96; Lass [Lassell, Memoirs R.A.S. vol. xxiii], plate I, fig. 1; Secchi [A.N. xlv], p. 60; Tempel [A.N. lviii], p. 240; G.P. Bond [Ann. Harv. Coll. Obs. v]; Ld R [P.T. 68]; Secchi [Mem. Soc. Ital. 3rd Ser. I]; d'A 3 [d'Arrest, Undersögelser over de nebulose Stjerner, Copenhagen, 1872], plate II; H.C. [Winlock and Trouvelot, Annals of Harvard College Observatory, vol. viii], plate XXIV; Wash. [Holden and Trouvelot, Washington Observations, 1874, App. I], plate VI, fig. 4; Holden [Wash. Obs. 1878, App. I]; Tempel [Ueber Nebelflecken (Abh. d. K. Böhm. Gesell. d. Wiss. 1885)], plate II.

[Descriptions of 762 Nebulae and Clusters photographed with the Crossley Reflector. Publ. Lick Obs., No. 13, Part I, p. 9-42]
NGC 1976, RA= 5:30 , Dec=- 5:28. The Great Nebula in Orion; [Publ. Lick Obs.] Vol. VIII, Plates 10 and 11. ``Circumsitae nebulae descriptio `res Deo improba' '' (D'Arrest.) 0 s.n.
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