NGC 2237 / NGC 2238 / NGC 2246 (Sh2-275, LBN 949) /

NGC 2244 (Lund 229, Cr 99) (part of 'Rosette Nebula')

Bright Nebulae / Open Cluster in Monoceros

Center of field at approximately: RA 06 hours 31 minutes 39 seconds, Dec +05 degrees 01 minutes 42 seconds

Size: 80' x 60' / 23' (30') Magnitude: -- / 4.8 Class: Emission (Sharpless) 1 2 3 / II 3 r n

North is up

West to the right

Telescope:

 8" f5 Newtonian reflector

Camera:

  ST-8XME, self-guided, binned 1x1, temp -25c & -20c, camera control MaxIm DL 4.56

Image:

Lumicon Red filter, 680 minutes (68 x 10 minute subs), 03/12/13/16/17/2009; seeing 1.8-3.2 FWHM per CCDStack

Processing:

CCDStack 1.5.2.1, Photoshop 7.0

Location:

 Rolling Roof Observatory, Thousand Oaks, CA 91360 (+34d 13m 29s -118h 52m 20s)

Notes:

This image replaces a red filtered 120 minute Track & Accumulate image from 03/21/2006. The image is centered on the 'hole' of the much larger 'Rosette Nebula'. The center of the open cluster is approximately at the brightest star near the lower left of this image. The Rosette Nebula (NGC 2237 / NGC 2238) is approximately 80' x 60' in size, and brighter parts of it carry numerous designations. See here for my 14.5" f5 Newtonian Kodak Tech Pan film image of this area. See here for Robert Gendler's stunning 'mega mosaic' of the Rosette Nebula.

According to "Star Clusters", by Brent Archinal and Steven Hynes, the size of the open cluster NGC 2244 is 30 arc minutes.

The Rosette has many NGC designations ... here are just two from the NGC / IC Project:

Contemporary Visual Observation(s) for NGC 2237

NGC 2237 = Rosette Nebula = Sh 2-275
06 30.3 +05 03
Size 80x60

13.1" (11/5/83 and 1/23/82): the complete annulus of the Rosette Nebula was 
clearly visible surrounding the naked-eye cluster N2244.  Appears brightest and 
broadest in the NW region with a bright knot in the NE quadrant (N2246).  The SE 
portion is split into two shells.  The western section has sharp corner on the 
inner edge.  N2237 refers to a brighter section in the western section of the 
Rosette.  The brighter embedded cluster, N2244, is offset within the 20', darker 
central region, and the SE end of the cluster (including the brightest member 12 
Mon) spills over into the nebula.

8" (1/1/84): complete annulus easy visible in field at 42x or 8x50 finder with 
filter.

Naked-eye (1/8/00): using an OIII filter, the apparent diameter of the bright 
cluster (N2244) noticeably increases in size due to the surrounding nebulosity 
although the overall brightness is slightly less with the filter.

- by Steve Gottlieb
Historical Research Notes / Correction for NGC 2237
NGC 2237, 2238, and 2246 are all parts of the large annular HII region often 
called the Rosette.  Embedded in the middle of the nebula is a bright cluster
of young stars, NGC 2239 = NGC 2244 (which see) discovered by WH, and observed
again by JH.

Albert Marth is apparently the first to see any part of the nebulosity (NGC
2238, which see), though Lewis Swift was the first to call attention to its 
great size.  Barnard ran across the nebula independently in 1883 while 
sweeping for comets, and his observations inspired Swift to finally publish
a note about it in 1884.  Scanning the area again in 1886, Swift found part
of the eastern side of the nebula (NGC 2246, which see), but it was not until
Barnard began his photographic work at Lick in the early 1890s that the full 
extent of the nebula became known.

The position for NGC 2237 given by Swift in his second list of nebulae 
actually comes from Barnard, though it is about 45 seconds of time west of the 
center of gravity of the western part of the Rosette to which it refers.  
Barnard's description is accurate, however, and there is no question as to 
which part of the nebulosity he saw. - Dr. Harold G. Corwin, Jr.
Contemporary Visual Observation(s) for NGC 2244
NGC 2239 = N2244 = Cr 99 = Mel 47 = OCL-515 = Ced 76b
06 31 55 +04 56.6

See observing notes for N2244.

Listed by JH (h392) under the synonym VII 2 = N2244.  Catalogued in Lynga as 
OCL-512 although h's description "the place of a *8 in most compressed part of a 
large, poor but brilliant cl." describes N2244 (central cluster in the center of 
the Rosette) with a 1.0 tmin error in RA.  Although h originally made the 
equivalence with N2244, he listed N2239 separately (probably because of the 1 
tmin difference in RA) in GC. The identification with N2244 was noticed by 
Alister Ling.  Reinmuth puts both together as "NGC 2239 and 2244 B Cl, pL, P, 
sc, B st in eeL dif neb".

- by Steve Gottlieb

NGC 2244 = Cr 99 = Mel 47 = OCL-515 = Ced 76b = N2239
06 31 55 +04 56.6
V = 4.8;  Size 24

17.5" (2/11/96): unusually bright, large cluster of ~15'x5' elongated NW-SE in a 
rectangular outline and situated in the heart of the Rosette Nebula!  The 
brightest 8 mag 6/7 stars lie along the sides and vertices of the rectangle with 
the brightest member, yellowish 12 Mon (V = 5.9), residing at the SE vertex.  
There are ~40 stars within the cluster although the only concentration is 15 mag 
11/12 stars surrounding mag 6.8 SAO 114010 (W of center) and trailing to the E 
towards the wide bright pair of mag 8 stars E of center (one of these stars is a 
close double).

8": bright, large cluster in the center of the Rosette Nebula.  The six 
brightest stars form a rectangular outline with the brightest star 12 
Monocerotis (V = 5.9) at the SE corner.  At the N and NW corners of the 
rectangle are two bright wide pairs with mag 7/8 stars.  Many faint stars are 
near the center surrounding the wide pairs.  Faint naked-eye cluster in dark 
sky.

- by Steve Gottlieb
Historical Research Notes / Correction for NGC 2244
NGC 2239 = NGC 2244, the bright young cluster in the center of the HII region 
called the Rosette (see the discussion under NGC 2237), was found by WH.  JH 
recovered it 30 years later during his northern sweeps from Slough, though he 
made an error of 1 minute of time in the position.  Neither noticed the 
nebulosity around the cluster; that remained for Marth, Swift, and Barnard to 
bring to our attention. - Dr. Harold G. Corwin, Jr.