by Anthony Ayiomamitis
The open cluster NGC 7039 in Cygnus depicted above is comprised of approximately 100 member stars which are not very well detached from the background sky owing to the fact the cluster is in a very rich section of Cygnus and is comprised of many mag 11-13 member stars near the core as well as a handful of brighter stars to the northeast (SAO 50547 at mag 6.69 and SAO 50561 at mag 7.83) and southwest (SAO 50531 at mag 8.82 and GSC 3588:1025 at mag 6.6) which effectively border the cluster. NGC 7039 spans 25 arc-minutes in diameter or nearly the apparent diameter of the full moon and is estimated to be relatively young at 66 million years-old while lying at a distance of 3,100 light-years away. The cluster is best observed using low magnifications (50-100x) during summer when it is directly overhead. NGC 7039 was discovered by John William Herschel (1792-1871) in 1829.
Technical Details:
Date: July 13, 2010 @ 02:05 - 04:15 UT+3
Location: Athens, Greece (38.2997° N, 23.7430° E)
Equipment: AP 160 f/7.5 StarFire EDF, AP 1200GTO GEM, SBIG ST-10XME, SBIG CFW10, SBIG LRGB filters
Integrations: LRGB @ 30:30:30:30 using 3-/6-min subs, 1x1 binning, 1.17"/pixel, -12.5d C
Further details are available here.