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NGC 2477
Mel 78, Cr 165, Rb 65
RA 07:52:17
Dec -38°32.0'
Open
cluster |
This open cluster was discovered by Lacaille
and included in his 1755 catalogue as Class I No. 3, classifying it as a nebula.
In his half-an-inch 8x telescope he saw it as a "big nebula 15' to 20'
diameter."
James Dunlop observed this object from
Paramatta, New South Wales, and included it as No. 535 in his catalogue of 1827.
Using a 9-inch f/12 telescope, he described it as "a pretty large faint
nebula, easily resolvable into small stars, or rather a cluster of very small
stars, with a small faint nebula near the north preceding side, which is rather
difficult to resolve into exceedingly small stars. This is probably two clusters
or nebula in the same line; the small nebula is probably three times the
distance of the large nebula." Dunlop recorded this cluster on 5
occassions.
h: "Superb cluster, gbM, 20' diameter,
much more than fills the whole field. Stars 10 and 11th mag all nearly equal."
On a second occassion he called it "Cluster 6th class, bright, large, rich,
not very highly condensed in the middle. Stars very remarkably equal. All 12 or
13th mag. Very few 14th mag; none 11th mag. A fine object." His third
observation was recorded as "a very beautiful large cluster, very rich;
stars nearly equal, and 12th mag, gbm, not much compressed in the middle; more
than fills the field. (N.B. It is visible in the finder of the equatorial, and
in the telescope of that instrument appears as a fine cluster."
Burnham calls this "probably the finest
of the galactic clusters in Puppis." The NGC calls it a remarkable cluster,
rich and well spread-out, consisting of stars of 12th magnitude. Burnham notes
that it is a "striking group, somewhat smaller than M46, but richer and
more compact." P. Doig called it "almost globular" and Shapely
wrote of it as "in superficial appearance... the richest of galactic
clusters; or perhaps it is the loosest of globular clusters."
Hartung writes that the cluster is "broadly
concentrated to a dense centre of 12'; the stars are very numerous and many are
grouped in curved lines and sprays with dark sky between, making a beautiful
effect. A 6" shows this cluster fairly well."
Harrington says the cluster "appears like
a ball of celestial cotton spanning about a Moon's diameter when viewed through
low-power binoculars. With a rich-field telescope, the cluster's fuzziness
dissolves into a myriad of faint points of light. In all, 160 stars dwell within
NGC 2477, though none shine brighter than 10th magnitude."
Glen Cozens notes that "a moderate
aperture will show it as well-resolved stars against a grainy background of
faint starlight."
Tom Lorenzin, in the electronic version of "1000+
The Amateur Astronomers' Field Guide to Deep Sky Observing", notes: “6M;
25' diameter; hundreds of 10M and dimmer members; use wide field at 50x; great
binocular object just N of 4M b PUP.”
Steve Coe, observing with a 13” f/5.6,
notes: “Bright, large, very, very rich, very compressed. 180 total members
estimated by counting 45 stars in the northeast quadrant at 100X. There are many
lovely dark lanes that wind there way through several star chains and an
ever-present glowing backround of more stars. I can resolve 20 stars in the
11X80 finder.”
11x80: A really beautiful
sight; 11x80 binoculars show it as a large round, nebulous patch, with no stars;
a bright star, b Pup, lies to its southeast. The cluster is easy to locate,
since it lies north of the pretty bright b Puppis. A hasty glance shows nothing,
but the slightest averted vision shows a glorious glow, a faint glimmer of
starlight, which is remarkabley large. This is quite unexpected, because you
don't expect a patch of barren sky to suddenly burst into a puff of starlight.
It looks like the faint extended halo of a comet. Contrasts nicely with nearby
NGC 2451. Even poor conditions, with light pollution and haze, don’t spoil
it; it remains a fantastic sight, appearing as a perfectly insubstantial object.
It is difficult to judge its shape - I would suggest it appears round. This
cluster is the slightest of glows imaginable, not a star in sight - remarkable!
(suburban skies) [AS]
6-inch f/8.6 Newtonian: What
a splendid object! Exquisitely minute stars almost fill the half-degree field of
view. The cluster appears distinct from the background sky, a myriad stars
evenly but densely spread out. This extremely rich gathering has no central star
or otherwise dominant member. There is a chain of stars leading off to the
north-east. The dark lanes are very noticeable in this cluster. The cluster has
a bright triangular stellar region, defined on the east and north by the two
dark lanes, which intersect at an almost 90 degree angle. The eastern dark lane
ends in a definite bulbous lobe, which is the most prominent in the cluster. The
dark lane making the southern edge also has a bulbous ending; the cluster seems
to vaguely extend beyond this barrier. These two dark lanes look somewhat like
golfclubs, crossed near their handles with the heads facing inwards. The effect
of the dark lanes on the shape of the cluster is quite noticeable. At low
(finding) power initially, and afterwards, the impression is created that the
cluster is box-shaped, with the eastern edge more sharply outlines. (exurban
skies) [AS]
10-inch f/5 Newtonian: A
10-inch f/5 at 30x evenly resolves the cluster into small stars; it appears just
under a third of a degree across, and although it has an irregular outline, the
stars are pretty evenly distributed across the surface; there does, however,
appear to be a more concentrated triangular region cutting right across the
cluster's surface. At 66x, about half a dozen brighter-than-average (10th mag)
stars are distributed across the clusters surface, causing it to appear lumpy
and irregularly condensed. The textured appearance of this remarkable cluster is
most pleasing. It really is a most beautiful sight, and forms a nice contrast
with the bright star (b Pup) which can be seen in the same field; it sort of
looks as if once there were two bright stars here, and one suddenly
disintegrated into faint shards of light. (suburban skies) [AS] |
