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NGC 2287
M 41, Mel 52, Cr 118, Rb 40
RA 06:46:02
Dec -20°45.5'
Open
cluster |
In the Appendix to the 1912 'Scientific Papers
of Sir William Herschel' this object is described as "1784, October 20, 20
feet telescope, a large cluster of very coarsely scattered large stars."
The Earl of Rosse, observing with a 72-inch
f/8.8 speculum telescope, noted "Nov 25, 1851. A coarse bright cluster."
In the 5th edition of Webb's Celestial Objects
for Common Telescopes it is described as "superb group, visible to naked
eye. Four degrees beneath Alpha. Larger stars in curves, with ruddy star (Espin:
variable?) near centre, 5.5-inch ."
Burnham calls it a fine bright cluster,
visible to the naked eye and partially resolvable in field glasses. It is a "beautiful
object in low power instruments, and is a favourite of deepsky observers. It
contains about 25 bright stars and many fainter ones ... there is a bright
reddish star near the centre; many of the other stars seem to be arranged in
curving rows and groups. ... M41 was stated by C.E. Barns to be "possibly
the faintest object recorded in classical antiquity"; it was mentioned by
Aristotle about 325 B.C.as one of the mysterious 'cloudy spots' then known in
the sky. Approximately 100 stars are now recognized as true members of this
cluster, ranging in brightness from 7th to 13th magnitude." The brightest
member is a K3 II star of 6.93 magnitude, which is the central reddish star. The
third brightest star is a type K1 II (7.46 mag), the fifth brightest is type K0
II (7.82 mag) and the sixth brightest is a type K4 II (7.87 mag).
Trumpler (Lick Obs Bul, Vol 14, No. 420) gives
the diameter as 32' and the class as 1 3 r. The RNGC (Sulentic and Tifft 1973)
notes that this is a 5.0 mag open cluster.
Hartung calls this a fine cluster, noting the
presence of "some delicate pairs and triplets with a fine yellow star near
the centre."
Houston notes that he has easily seen this
cluster with the naked eye and that it is brighter than M11 in Scutum. He adds:
"Telescopically, it shows curved lines of stars."
Harrington notes that this "dazzling"
cluster is visible to the naked eye on any dark night. He writes: "Even
through a veil of light pollution, low-power binoculars should pick up about two
dozen of the cluster's stars. Telescopes show M41 bursting with splendor. The
brighter members create a central keystone asterism strongly resembling that of
the constellation Hercules. An added bonus, many of M41's stars form closely
tied pairs or triplets. By slightly defocusing the telescope's image, many will
shine with hints of yellow, orange, and blue-white. Most of the suns are crammed
within a half-degree circle, though some stragglers lie farther out."
Sanford notes that this cluster is "visible
to the naked eye, located where you would find the dog's heart. It contains
several fairly bright stars and multiples. The cluster is almost half a degree
in diameter."
Donald J. Ware:”Large and splashy, this
fine open cluster is easily seen as a hazy patch to the naked eye, and is fully
half a degree in diameter in the telescope. About 60-70 stars can be seen at low
power, in many curving chains. The cluster is dominated by a bright orange star
near its center. A great open cluster.”
Tom Lorenzin, in the electronic version of "1000+
The Amateur Astronomers' Field Guide to Deep Sky Observing", notes: “4.5M;
38' diameter; large but sparse; best in 1 degree field at low-x; 6M star at S
edge is 12 CMA; 4 degrees S and a little E of Sirius (Alpha CMA); good binocular
object.”
Steve Coe, using a 17.5” f/4.5, notes: “(M41)
bright, large, somewhat compressed, 60 members with orange star in center. Many
curved lines of stars at 100X. Easily seen in 8X50 finder.”
Todd Gross, in a contibution to the IAAC,
observed it from Cancun, Mexico, with an 80mm APO refractor at various powers.
He writes: “Very nice to view so high in the sky from this (relatively)
southern locale. A moderately rich, large cluster, very easy to pick up in 8x32
binoculars. In the scope, medium-bright stars, about 50 of them, many equal in
brightness, but some weaker members as well. Showed best at around 30x. Took up
nearly the entire field of view at 32x (52 deg apparent field size) It was not
round, but elongated somewhat, seemingly oriented SE-NW.
10x50: Contains a few bright
stars, especially two in centre of cluster. The rest is fainter and shows better
with averted vision. An unresolved element remains. With averted vision a
central bar is seen, with another (shorter) one on the left." (suburban
skies) [DC]
10-inch f/5 Newtonian:
Observing from the 1500 metre plateau of the South African Astronomical
Observatory observing site in Sutherland, I was surprised at the ease with which
this cluster could be seen with the naked eye - it is an easy small patch of
light in the CMa milky way.
This is a beautiful cluster in any instrument;
in a 10-inch f/5 at 30x it appears to span over almost 3/4 of a degree. It is
well spread out and yet stands out well as a fine group. It has a dozen or so
really bright members, the rest of the members fading away as they grow dimmer.
To the side of the cluster, just off centre, lie two stars which appear to be
slightly red; the outermost one more prominent. The stars right in the centre
form a semi-circular grouping of about 7 members. (suburban skies) [AS] |
