Astrophotography by Anthony Ayiomamitis

Deep Sky Object Image Gallery

Open star clusters are widely distributed in our galaxy and represent a loose collection of stars which number from a few dozen to a few hundred stars and are weakly-held gravitationally. Perhaps the three most famous such open clusters are the Pleiades (M45) in Taurus, the Beehive (M44) in Cancer and the double cluster in Perseus. They are all characterized with a handful of hot and white prominent stars and nebular material surrounding these stars.

Note: Open cluster NGC 2244 in Monoceros depicted below lies at the core of the large and expansive Rosette emission nebula and, quite often, the NGC 2244 designation is also associated with the nebula itself. Comprised of over 100 member stars which are interspersed and without a central concentration, the brigher 0B-association member stars help illuminate the surrounding gas. These stars have blown away the gas in the immediate vicinity with their intense radiation, thus leaving behind a hole within the nebula. NGC 2244 spans approximately 23 arc-minutes in diameter and lies 4715 light-years away. In addition to the double classification (NGC 2239 and NGC 2244), a number of other classifications exist including NGC 2237 and NGC 2238 to the immediate west of the cluster as well as NGC 2246 to the northeast representing various small portions of nebulosity involving the Rosette nebula itself. Also of interest are the various Blok globules visible in the periphery and which often lead to the formation of binary and multiple star systems. NGC 2246 was discovered by John Flamsteed (1646-1719) in 1690.

Please click on the image below to display in higher resolution (1200 x 950)

Image Details
NGC 2239/2244 - Open Cluster in Monoceros
Imaging Details
NGC Number:
2239 / 2244

Common Name(s):
Rosette Nebula

Other Designations:
Cr 99, OCL 515

Object Type:
Open Cluster

Object Classif:
II 3 r n


RA / Dec:
06h 31m 54s /
04 56' 30"

4715 light-yrs

Object Size:
23' x 23'


Nov 05, 2010
02:25 - 5:55 UT+2

Athens, Greece

AP 160 f/7.5 StarFire EDF
Baader 7nm H-a
SBIG LRGB + IR-block

H-a :  080 min (08 x 10 min)
Lum :  030 min (10 x 03 min)
Red :  030 min (05 x 06 min)
Green :  030 min (05 x 06 min)
Blue :  030 min (05 x 06 min)
Binning :  1x1 (Lum, H-a),
 1x1 (RGB)

Image Scale:
1.16" per pixel

Ambient : + 17.0 C
CCD Chip : - 12.5 C

CCDSoft V5.00.201
CCDStack V1.6.0.5
eXcalibrator V1.0.4.0
Aladin V6
Photoshop CS2