NGC 3766 Mel 107, Cr 248, Rb 92 RA 11:36:05 Dec -61° 35.0' Open
cluster |
This cluster was discovered by Lacaille and
included in his 1755 catalogue as Class III No. 7. In his half-an-inch 8x
telescope he saw it as "three faint stars in nebulosity."
Dunlop 289: "A pretty large cluster of
stars of mixt magnitudes, about 10' diameter. The greater number of the stars
are of a pale white colour. There is a red star near the preceding side; another
of the same size and colour near the following side; another small red star near
the centre; and a yellow star near the south following extremity, all in the
cluster."
h: "the preceding of two chief stars of a
fine, large, loose, round cluster of stars 8..12th mag; gradually pretty much
brighter in the middle, fills field; 150..200 stars." His second
observation recorded "A very fine cluster class VII; nearly round, 8'
diameter, slightly compressed in the middle, stars of 9..15th magnitude; place
that of an orange star 9..10th mag following the centre."
Hartung calls it a "fine scattered
cluster with broad central condensation [which] is effective even for small
apertures. It is at least 15' across, merging into a rich field with a pattern
of star loops giving a lobed appearance and containing orange, yellow, white and
bluish stars."
Burnham calls it a pretty large, pretty rich
compact cluster, 12' across, containing about 60 stars of 8..13th magnitude,
including Inness 421, a double star of 7th and 10th mag components 1.5
arcseconds distant in PA 117 .
Harrington writes that "smaller
instruments show this open cluster as a very pretty, compact swarm of stars
buried within the nebulous glow of fainter suns. A 6-inch telescope resolves
about 80 stars of 7th to 13th mag set in an arrowhead. The brighter stars - some
appearing golden, others bluish - form an arc across the cluster's northern
perimeter."
Gerd Bahr-Vollrath (Noosa Heads, Queensland,
Australia) writes in the The Webb Society Nebulae and Clusters Section Report
No. 11, January 1993: "Fairly large, rich and bright. Set in a dense and
rich region of the southern Milky Way, it is difficult to tell how many stars
actually belong to the cluster. My guess is about 60, these ranging from mag 8
downwards. Many apparent chains and loops of stars make NGC 3766 a very
attractive cluster. (8-inch f/12 SCT)"
10x50: Small bright
triangle, very distinct from background. Seven brighter members can be resolved
in the cluster. Taken together with the surrounding star field, forms a 2-shaped
asterism (suburban skies, dew) [RH]
11x80: Magnificent! A
beautiful tight grouping of stars; grander version of nearby 4103. Lies in a
rich field; part of a four-degree long snaking chain of bright stars. Due north
of the cluster is a nice triangle of 7th mag stars. The triangular cluster
appears like a lop-sided Jewelbox (elongated 2.5 : 1, pointing northwest).
Three bright stars in a narrow triangle, with stars scattered between them
irregularly. The two stars forming the northern edge of the triangle are a
remarkable deep red. At least 15 stars can be make out as fine points of light,
and averted vision shows surrounding glow of many more. Chains! A short
chain of about five stars, starting north of the cluster, crosses the northern
leg of the triangle and then, inside the triangle, appears to curve back,
forming a stretched S-shaped chain. Rui Henriques pointed out that the long
snake-like curve of field stars can be made to look quite like a 2 -
this asterism lies between 11:48 and 11:46, -61 and -63.5; contains Lambda Cen
in the tip. (suburban skies) [AS]
4-inch f/15 Unitron refractor:
A beautiful, 9 arcmin, scattering of bright and faint stars, well resolved in
the 42x sweeper eyepiece. Shares this wide field with very bright stars (two
west-ish, one east). The 25 arcmin field of the K18-eyepiece frames the cluster
perfectly, showing a wonderfully intricate grouping of large and small stars -
sketch made. The cluster has a vague oblong shape, north-east to south-west.
Very rich, and large brightness range - six or so bright stars in the grouping,
filled in by a host of smaller ones. There are two distinct orange stars - one
on north-east and the other on south-west edge of cluster. (suburban skies) [AS]
10-inch f/5 Newtonian: A
wonderful tight compact grouping in a rich field filled with bright stars. The
cluster sports two red beacons on opposite sides. At 30x, direct vision shows
about thirty stars, but averted vision brings out the fainter members, filling
in the empty spaces, resulting in a fine sprinkling of large and small stars
making up this very rich cluster. At 120x the cluster is framed beautifully,
showing it to be very rich in small 10th mag and fainter stars. (suburban skies)
[AS] |