by Anthony Ayiomamitis
The large and bright emission nebula Sh 2-157 in Cassiopeia (near the northern border with Cepheus) lies 8,150 light-years away and spans another 215 light-years across. Sh 2-157 is described as a ring nebula surrounding the Wolf-Rayet star WR 157 (SAO 20512, mag 9.58) and is in the immediate vicinity of both the open cluster M52 as well as the stunning Bubble Emission Nebula. Also visible in the field of view of the image above is the small open cluster NGC 7510 at the top right quadrant which is comprised of approximately 100 member stars, is well-detached from the background and is relatively bright at mag 7.9. Similarly, the bottom right quadrant has the small elliptical planetary nebula PLN 110-0.1 (aka WeSb 6, RA: 23h 12m 12s, Dec: +59°36'02") with an apparent diameter of two arc-minutes.
Technical Details:
Date: Jul 31-Aug 1, 2010 @ 22:20 - 05:10 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 @ 240:50:50:50 using 10-/20-min subs, 1x1 binning, 2.65"/pixel, -12.5d C
Further details are available here.