About image Sh2-157 is a large emission nebula in Cassiopea constellation: due to its particular shape it is also called “Lobster claw” nebula.
It is located on the Perseus Arm, one of the main spiral arms of Milky Way, and it is directly linked with the association OB Cassiopeia OB2: inside this nebula there is a cluster of very young stars called Mrk50 and on the upper side of nebula it is also clearly visible the open cluster NGC 7510. Many other nebulas are visible in this image: among the others the Bubble Nebula NGC 7635 on the left lower side and the very bright HII region NGC 7538 on the left side.
Technical data Optic TS Optics 76 EDPH - Aperture 76mm, focal lenght 342mm, f/4.5 Mount Skywatcher EQ6R Camera ZWO ASI 294MM Pro with external filter wheel 7 positions Filters Antlia 36mm RGB, Antlia 36mm Ha 3.5nm Guiding system Artesky Ultraguide 32mm Exposure details R 52x120" bin2 -15C G 52x120" bin2 -15C B 52x120" bin2 -15C
Ha 46x300" bin2 -15C
Gain 120, offset 30 Total integration 9h2' Acquisition Voyager, PHD2 Processing Pixinsight 1.8, Photoshop CS5 SQM-L NA Location Promiod (Aosta Valley, Italy) Date 8/10/11 August 2021