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NGC 2516
Mel 82, Cr 172, Rb 69
RA 07:58:24
Dec -60° 51.0'
Open
cluster |
This cluster was discovered by Lacaille and
included in his 1755 catalogue as Class II No. 3. In his half-an-inch 8x
telescope he saw it as a "very close group of 10-12 stars."
Sir John Herschel observed it frequently while
at the Cape of Good Hope with an 18-inch f/13 speculum telescope. His first
record reads: "An orange-coloured star 8th magnitude, in middle of a large
and magnificent cluster of perhaps 200 to 250 stars 8..16th mag. Many of the
larger magnitudes, and really a superb object. Very visible to the naked eye,
etc." His second entry reads: "Place of a double star in a fine
scattered pretty rich cluster of large stars, which fills field, and may contain
150 stars, large and small. No other remarkable double star in it." His
next entry describes it as "A star 6th magnitude, one of the chief of a
large splendid cluster, coarse, filling field, 20'..25' diam., stars 9..13 mag."
His fourth observation saw it as "a star 6th magnitude, in a superb, very
large cluster. Rich and brilliant. In the northern part about 20 seconds;
following this star is a star of 5th magnitude, ruddy. Has two or three neat
doubles in it. The whole region is rich in large stars." His final
observation was recorded as: "chief double star is a fine cluster 7th
class, stars 7..12 mag. Fills field, and has outlying stars two or three fields
preceding."
Burnham calls it a "large and brilliant
group, easily visible to the naked eye, with more than a 100 stars scattered
over a field 1 degree in diameter. The bright red giant star near the centre is
very obvious in small telescopes; T.W. Webb called it orange.
Hartung calls it a "beautiful open
cluster, at least 50' across, needs a large field and makes then a glorious
sight with its scattered groups and irregular spray of stars, effective for
small apertures. A dainty pair h.4031 (7.8, 8.7, 6 arcsec, 358 ) is S.f. from
the centre and another, h.4027 (10.0, 10.2, 9 arcsec, 115 ), is 10' preceding."
Glen Cozens writes: "NGC 2516 at the
False Cross' foot is one of the Southern Hemisphere's best open clusters and is
easily visible to the naked eye as a distant frosty glow. A dazzling red star
forms the heart of NGC 2516, and a small telescope will show more than 100 stars
radiating from it."
Harrington writes that this is "an
impressive open cluster isolated in western Carina ... On dark, clear winter
nights, it is visible as a soft, pale smudge spanning about a Moon's diameter.
Yet with the slightest optical aid it erupts in starlight! Seven-power
binoculars resolve about a third of the 80 component stars, while a 6-inch
telescope can show just about all. A trio of orange orbs dominate the scene of
otherwise pure white stars. ... I also heard other binocularists [at the Winter
Star Party] whimper their sadness that [this] cluster is not visible from back
home."
Gerd Bahr-Vollrath (Noosa Heads, Queensland,
Australia) writes in the The Webb Society Nebulae and Clusters Section Report
No. 11, January 1993: "A large, bright and moderately dense cluster with
around 60 stars of a wide range of brightnesses. Visible to the naked eye.
(8-inch f/12 SCT)"
11x80: The cluster is almost
a degree in diameter, clearly visible to the naked eye just west and slightly
south of the tip of the False Cross. In binoculars -- what a splendid sight! A
glorious mass of stars on a rich field. The main body of the cluster is a
regular-sided diamond, lying north-south/east-west, and filled with stars. A
broad bridge of stars and stardust goes briefly northwards, and then branches
east and west, each branch ending in an orange star. The bridge has a small but
distinct black oval in its centre. On the east and west side of the bridge,
also, are black vacancies, helping to define the bridge. The eastern tip of the
diamond is capped by a bright off-white star. West of this star, near where the
bridge comes out, is an almost equal double star (southern component brighter).
Within the diamond, I count 22 large and small stars; amidst these is an
unresolved glow. (exurban skies, seeing 7, transparency 7, sky darkness 6,
lim.mag. at south pole 6.0 (naked eye), 10.7 (binoculars).) [AS]
6-inch f/8.6 Newtonian:
Stunning extremely large (more than fills 40 arcmin field) open cluster. Great
brightness range - large and smalls stars. A curved row of three 6/7th mag stars
to the north. Many dark, open areas within. Twenty brightest stars (including
two pale-yellow and four orange stars, and two sets of wide coloured double
stars), with a further estimated 80 fainter ones. The richest region lies to the
south, while there are two noticeable dark regions, one on the western side,
another on the eastern side. The two patches are well shown with the K9mm at
144x. (suburban skies) [AS]
10-inch f/5 Newtonian: A
10-inch f/5 at 30x shows it as a beautiful scattered group of bright and faint
stars, guarded on its west and north by three bright stars. Many streamers can
be traced with the eye. Near the centre of the cluster is wide, equal double
star, with one component, towards the south, clearly red in colour. One of the
far northern outliers also appears red. (suburban skies) [AS] |
