by Anthony Ayiomamitis
The large and dim emission nebula Sh 2-155 in Cepheus lies at a distance of 2400 light-years away and spans another 35 light-years across. It is characterized with rich H-II emission nebulosity with the northern half of the nebula being significantly brighter than the southern half. Commonly referred to as the Cave Nebula owing to a circular formation near the center resembling a cave, Sh 2-155 is also characterized with reflection nebulosity and as indicated by the small bluish nebulosity to the upper right as well as dark nebulae to the southwest. Star formation in Sh 2-155 is believed to be low.
Technical Details:
Date: Aug 12-13, 2010 @ 22:45 - 04:35 UT+3
Location: Athens, Greece (38.2997° N, 23.7430° E)
Equipment: Takahashi FSQ-106/f5, AP 1200GTO GEM, SBIG ST-10XME, SBIG CFW10, Baader 7nm H-α,SBIG LRGB filters
Integrations: HaRGB @ 140:60:60:60 using 10-/20-min subs, 1x1 binning, 2.65"/pixel, -10.0d C
Further details are available here. Due to light pollution, the RGB portion of the data was discarded and not blended with the Ha. Over the next few weeks, Sh2-155 will be revisited for a repeat attempt.