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NGC 1851
Bennett 32
Dun 508, ESO305-SC016, GCL-9
RA 05:14:05
Dec
-40°02.8'
Globular cluster |
Dunlop 508: "An exceedingly bright,
round, well-defined nebula, about 1.5' diameter, exceedingly condensed, almost
to the very margin. This is the brightest small nebula that I have seen. I tried
several magnifying powers on this beautiful globe; a considerable portion round
the margin is resolvable, but the compression to the centre is so great that I
cannot reasonably expect to separate the stars. I compared this with the 68
Conn. des Tems, and this nebula greatly exceeds the 68 in condensation and
brightness." Dunlop observed it on 5 occasions.
h: "superb globular cluster; all resolved
into stars of 14th mag.; very suddenly much brighter in the middle to a blaze or
nucleus of light; diam. in RA = 15 seconds of time. Difference of left and right
eyes in resolving this cluster very remarkable. Returning from the left to the
right eye, the object (in comparison) appears as if glazed over with a kind of
dull film." He recorded it a second time as "very bright; round; very
suddenly very much brighter in the middle; 3'; all clearly resolved into stars
from 14 to 16 mag except at the centre, where they are massed together into a
blaze of light." His final observation recorded it as "Superb globular
cluster, very bright; round; first very gradually then suddenly very much
brighter in the middle; 4'; resolved, the stars barely visible in strong
twilight."
Houston observed this cluster with 20x 5-inch
binoculars and wrote: "This ball of stars is quite bright, about 7th
magnitude, and must be a fine sight from the Southern Hemisphere. It was readily
seen at 20x."
Hartung writes "This beautiful globular
cluster rises sharply to a very bright centre; including outliers it is about 4'
across and well resolved into gleaming points. It is round but somewhat
unsymmetrical and resolution is doubtful with a 6-inch telescope but 3-inch is
enough to show the strong central condensation..."
Phil Harrington (1990, Touring the Universe
through Binoculars) notes "NGC 1851 is the only nonstellar deep sky object
found in Columba through binoculars. Due to its isolation from any bright stars,
observers should be prepared to search for a while. Once spotted, however, this
magnitude 7.3 globular cluster stands out quite well as a small, circular patch
of fuzzy light."
Steve Coe, using a 13” f/5.6, notes: “Very
bright, very large, round, very suddenly very bright middle, well resolved at
220X. Averted vision makes this globular cluster grow much larger. About 30
stars are resolved with several chains of stars winding outward from a blazing
core that is about 10" across. This cluster was seen in the finder.”
Steve Gottlieb, 17.5-inch: “small bright
core, large very mottled halo. About 20 stars are resolved mostly W of the
core.”; 13-inch: “mottled bright core, not resolved except for two or
three faint stars at the W edge.”; 8-inch: “small, very small bright
core, faint halo.”
Van den Bergh and Hagen ("UBV photometry
of star clusters in the Magellanic Clouds", Astronomical Journal, Vol. 73,
1968) find that the integrated V magnitude through a 60'' diaphragm is 8.02.
They remark: "color peculiar."
11x80: Very bright cluster,
not much fuzziness; looks like a star with a tiny halo, or a slightly
out-of-focus star. (urban skies, light and air pollution) [AS]
8-inch Newtonian, 66x: “Very
small, circular and symmetric. Intensely bright centre with a faint halo. Very
easily found but very difficult to resolve into stars.” (suburban skies) [GG]
15.5-inch f/9 Newtonian: At
220x, it has a bright nucleus and overall mottled appearance. A number of stars
sparkle out close to the nucleus. The nucleus is very small compared to the rest
of the body. (suburban skies) [AS] |
