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NGC 2548
Messier 48, Mel 85, Cr 179
RA 08:13:40
Dec -05° 47.0'
Open
cluster |
This open cluster in Hydra was long believed
to be a "missing" Messier object until astronomer Owen Gingrich linked
it with NGC 2548.
Recorded on December 7, 1786 by William
Herschel (H VI-022) with an 18.7-inch f/13 speculum telescope. He called it "a
beautiful cluster of much compressed stars, considerably rich, 10 or 12'
diameter. C.H. [Caroline Herschel] discovered it in 1783." In the Appendix
to the 1912 'Scientific Papers of Sir William Herschel' M48 is discussed: "1790,
March 5, Looked for the 48 of the Connoissance des Temps, but found that it does
not exist in the place mentioned by Wollaston. I looked with the Sweeper .. 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 telescope. They are scattered over a place near 2 degrees
in extent."
Hartung notes: “A large field is needed
for this bright open cluster, at least 30’ across; the stars are numerous
with many pairs, triplets and small groups which make a fine effect. Near the
centre is a delicate close pair.”
Houston notes that it has "a diameter
about equal to that of the Moon and it can just be seen by the unaided eye when
the sky conditions are right. My 5-inch apogee scope at 20x offers an excellent
view of the cluster as it brings out a thinly scattered blanket of background
stars."
Listed by the Herschel Club, described as “large,
bright nucleus with similar mag among stars. 8-inch, 48x.”
Tom Lorenzin, in the electronic version of "1000+
The Amateur Astronomers' Field Guide to Deep Sky Observing", notes: “5.8M;
40' x 25' extent; not so round, not so firm, not so fully packed (not a
kilbasa!); uneven distribution of knots and strings; good binocular object!.”
Donald J. Ware: ”This is a fine open
cluster over one half of a degree in diameter, and easily seen in binoculars. It
is composed primarily of fairly bright stars, loosely concentrated to the
center. I estimated about 75 stars in the area.”
Steve Coe, observing with a 17.5” f/4.5
at 100X, notes: “Somewhat scattered, Very Bright, can be seen naked eye, 12
stars are resolved in 8X50 finder, many chains of stars, little compressed, 7
*'s near center form an arch or boomerang shape. One * 9 mag orange at 60X. AZ
city-- just naked eye, 12 stars in 11X80. 13" 60X (38mm Erfle)--bright,
very large, pretty rich, little compressed, stars 9 to 13th mag. No fuzzy
background, seems all stars are resolved. There are several chains and bright
members. 61 stars counted in cluster.” ... “In my 5-inch binoculars,
its shape appears distinctly triangular.”
10x50: "quite large,
quite bright. Individual stars can be resolved. Quite a large number of stars.
In the middle of the cluster there is a brighter bar/wedge that stands out with
averted vision. Quite beautiful." (suburban skies) [DC]
11x80: Easy to find with
hand-held 11x80 binoculars. It appears as a very delicate object, a matte cloud
of starlight. [AS]
10-inch f/5 Newtonian: After
hunting the faint galaxies in this region with the 10-inch, it makes a pleasant
change to happen upon this nice cluster. The shape defies definite
classification, although it does appear to form a broad triangle lying northwest
to southeast. I estimate at least 50-60 stars here. The cluster is pretty well
spread out, the members forming no clear groupings other than a wedge-shaped
knot of 13 stars in the cluster centre. This triangular asterism lies northeast
to southwest, pointing towards the northeast. (suburban skies) [AS] |
