by Anthony Ayiomamitis
NGC 6618 in Sagittarius is yet another fine example of a large, bright and impressive emission nebula. Most commonly referred to as the Swan Nebula, it is also referred to as the Omega Nebula, the Horseshoe Nebula as well as the Lobster Nebula. This large expanse of H-II emission lies approximately 5000 to 6000 light-years away and spans another 40 light-years across. Similar to other emission nebulae, star formation is characteristic of the Swan Nebula but with only about 35 such new stars being visible and embedded within the nebulosity. It is believed the greatest proportion of such newborn stars are hidden behind the nebula and which help in its illumination. The Swan nebula was first detected by Philippe Loys de Cheseaux in 1745 and later by Messier in 1764.
Technical Details:
Date: July 06-07, 2010 @ 22:45 - 01:45 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, Baader 7 nm Ha, SBIG LRGB filters
Integrations: HaRGB @ 70:30:30:30 using 6-/10-min subs, 1x1 binning, 1.16"/pixel, -12.5d C
Further details are available here.