Lobster Claw Nebula (SH2-157)

Sharpless 157, also known as the Lobster Claw Nebula imaged from a very cloudy vacation at our cottage in Marion Bridge, Nova Scotia. The object is a low surface brightness emission nebula in the constellation Cassiopeia. It lies just south of the better-known Bubble Nebula (NGC 7635). Within this image are a few other objects. Planetary Nebula PLN 110-0.1 is located at the bottom in the lower left quadrant. The bright nebular spot near the center of the image is Lyn's Bright Nebula 537 (LBN537), also known as Sharpless 157a.

I'm not a fan of monochrome red images with completely white stars that seem to be the normal for this target and worked to avoid getting the same result here. There is a lot of subtle green and blue from OIII and H-beta in the region. The star colour is not close to true as this image used a filter, but they didn't turn out too badly.

Click on the image to see a higher resolution version. Click again to return to this page


Object SH2-157  Object RA 23:16:07, Dec+60:02:00
Date 21 August, 2020
Exposure 4 hours (24 X 10 minutes)
Conditions Bortle 4 skies, low light pollution levels.
ISO 800
Camera Canon 60Da DSLR
Optics Prime focus of a  SkyWatcher Esprit 120 f/7 APO refractor with a focal length of 840 mm
Filter Optolong L-eNhance
Location Marion Bridge, Nova Scotia
Processing This image was captured using Sequence Generator Pro, telescope control provided by Mosaic Engine and processed entirely in Images Plus.  Arcsinh stretch then a root n stretch to brighten the image. The result was cropped to remove stacking artifacts. Noise was reduced using a masked noise reduction with a frequency domain low pass filter then a detail preserving noise reduction filter with an edge mask..  Multi-point flatten used to remove gradient and balance the background. Curves and levels used to set the final image contrast. Star reduction and then a saturation boost using the HSL microcurve tool. Final image binned by two for web display.