Messier 48

Discovered by Charles Messier on February 19, 1771.
Independently rediscovered by Johann Elert Bode before 1782.
Independently rediscovered by Caroline Herschel in 1783.

Messier: M48.

February 19, 1771. 48. 8h 02m 24s (120d 36' 00") -1d 16' 42"
Cluster of very small [faint] stars, without nebulosity; this cluster is at a short distance from the three stars that form the beginning of the Unicorn's tail.

(As for M47, Messier did a reduction error, this time giving a position about 2.5 degrees north of the object, so that M48 was missing until Oswald Thomas identified it correctly but perhaps by chance, in 1934, with Herschel's H VI.22 (NGC 2548), and T.F. Morris, in 1959, pointed out that this is the only object in that region of the sky matching Messier's description.)

Bode (1782): Monoceros 35.

[From: Vorstellung der Gestirne auf XXXIV Kupfertafeln (Introduction to the Stars on 34 Copper Plates), 1782. Here p. 32, plate 25]
[Bode lists both Messier's wrong position [Mon 35] and Bode's correct position [Mon 38] for M48 separately. The latter indicates an independent rediscovery of M48 by J.E. Bode!]
Monoceros 35, after Messier. RA = 120:42 [08:02.8], Dec = -01:18. Small star cluster.
Monoceros 38, after Bode. RA = 120:30 [08:02.0], Dec = -04:30. Small Star Cluster with Nebula.

Caroline Herschel: No. 5.

No. 5.
March 8th [17]83. At an equal distance from 29 [Zeta] & 30 Monocerotis, making an equilateral triangle with those two stars is a nebulous spot. By the telescope it appears to be a cluster of scattered stars. It is not in Mess. catalogue.
[actually, Messier had reduced a wrong position - hf]

William Herschel: H VI.22.

H VI.22. Feb. 1, 1786. A beautiful Cl. of much com. st. consid. rich. 10 or 12' dia. C.H. discovered it in 1783.
A beautiful Cluster of much compressed stars, considerably rich. 10 or 12' diameter. Caroline Herschel discovered it in 1783.

[WH's journal note] Lina [CH]. equilateral triangle with 29 & 30 Monocerotis, to the south, a Cluster of scatter'd stars.

[Scientific Papers, Vol. 2, p. 657; Dreyer's remark: Not in NGC, 8h 7m, 91d 32' for 1860. This is not our modern M48 - hf]
1790, March 5 (Sweep 935). Looked for 48 of the Connoiss. des Temps but found that it does not exist in the place mentioned by Wollaston.
Mem. (*) I looked with the Sweeper for the 48th of the Conn., &c., and found a parcel of coarsely scattered stars , not deserving the name of a cluster; which on account of their being too far from each other could not be seen clustering in my 20 ft. Teles. They are scattered over a place near 2d in extent. [again, this is not M48 - hf]
(*: Dreyer's note: At the end of the same sweep)

John Herschel (1833): h 496.

h 496 = H VI.22.
Sweep 235 (February 20, 1830)
RA 8h 5m 18.7s, NPD 95d 14' 40" (1830.0) [Right Ascension and North Polar Distance]
Fine L, p rich, very straggling cluster of st 9 . 10 and 10 . 11 m. The straggling edges extend a full field either way. Place of a D * in the most comp part.
Fine large, pretty rich, very straggling cluster of stars of 9th to 10th and of 10th to 11th magnitude. The straggling edges extend a full field either way. Place of a double star in the most comp part.

Sweep 234 (February 19, 1830)
RA 8h 5m 18.8s, NPD 95d 18' 54" (1830.0)
A superb cl which fills the whole field; st 9 . 10 .... 13 m and none below, but the whole ground of the sky on which it stands is singularly dotted over with infinitely minute points. Place that of a B st, the s of two which point into the concavity of an arc.
A superb cluster which fills the whole field; stars of 9th and 10th to the 13th magnitude - and none below, but the whole ground of the sky on which it stands is singularly dotted over with infinitely minute points [stars]. Place that of a bright star, the southern of two which point into the concavity of an arc.

Sweep 21 (March 12, 1826)
RA 8h 5m 26.1s:, NPD 95d 18' 2" (1830.0)
A cl of about 100 large st 10 and 11 m.
A cluster of about 100 large [bright] stars of 10th and 11th magnitude.

Smyth: CCCXVIII [318]. H. VI.22 [M48].

CCCXVIII. 22 H. VI. Monocerotis [now Hydrae].
AR 8h 05m 40s, Dec N 5d 19'.2
Mean Epoch of Observation: 1834.29 [April 1834]
Position 205d.0 (w 1), Distance 4".0 (w 1)
A neat but minute double star, in a tolerably compressed cluster on the Unicorn's flank, and lying 14deg south-east of Procyon. A 9 1/2 [mag], and B 10, both white. This object is in the middle of a splendid group, in a rich splashy region of stragglers, which fills the field of view, and has several small pairs, chiefly of hte 9th magnitude. It was discovered by Miss Herschel in 1783, and was classed by WH [William Herschel] in February, 1783.

John Herschel, General Catalogue: GC 1637.

GC 1637 = h 496 = H VI.22. C.H.
RA 8h 6m 50.1s, NPD 95d 22' 30.6" (1860.0) [Right Ascension and North Polar Distance]
Cl; vL; pRi; pmC; st 9...13. 7 observations by W. & J. Herschel.
Cluster; very large; pretty rich; pretty much compressed; stars from 9th to 13th magnitude.

Dreyer: NGC 2548.

NGC 2548 = GC 1637 = h 496 = H VI.22; C.H.
RA 8h 6m 50s, NPD 95d 22.5' (1860.0) [Right Ascension and North Polar Distance]
Cl, vL, pRi, pmC, st 9...13; = M48
Cluster, very large, pretty rich, pretty much compressed, stars from 9th to 13th magnitude.

Dreyer (IC I)

[Introduction to the IC I catalog]
Two clusters in MESSIER's catalogue do not occur in the New General Catalogue, and may perhaps be mentioned here. They are (for 1860):

    M. 25  18h 23m 17s  109d  2'.0  Cl of S st [cluster of small (faint) stars]
    M. 48   8h  6m 54s   91d 32'.1  Cl of S st [cluster of small (faint) stars]

[This remark concerns Messier's wrong position, not "modern" M 48 = NGC 2548]

Oswald Thomas (1934)

[From: Astronomie, Tatsachen und Probleme. Verlag "Das Bergland" Buch, Deutsche Vereins-Druckerei AG, Graz, Wien, Leipzig, Berlin, 1934. 10. Abschnitt, Himmelstafeln. (14) Sternhaufen und Nebel. P. 137]
M 48, RA: 08:09, Dec: -06 (1900.0), NGC 2548, Hydra, Open Cluster.
[This identification is given without any further comment. - hf]

T.F. Morris (1959)

[Identified M48 with NGC 2548 according to Owen Gingerich (1960) and others]

Owen Gingerich (1960)

[Sky & Telescope, Vo. 20, No. 4 (October 1960), p. 196]
Although the circumstances of M48 are not so obvious, only one cluster of the size and brightness likely to be recorded by Messier is found in the region near "the three stars that form the beginning of the unicorn's tail" (Zeta, 27, and 28 Monocerotis). Dr. Morris has pointed out that this cluster, NGC 2548, has the same right ascension as the position given for M48. (Allowance must, of course, be made for precession in comparing Messier's figures with modern positions).
The declination disagrees by about 5 degrees. Since no conspicuous star is located 2 1/2 degrees away in declination, we cannot account for this position by another error in sign. It seems unlikely that the comparison star was misidentified, since the right ascension is probably correct. Messier did not publish the name of the star used, and his original records are apparently no longer extant. [..]
Thus, a careful survey of the region described by Messier leads to the conclusion that NGC 2548 is the cluster the French observer intended as his 48th object, for lack of any cluster nearby that fits the description.