Dear Reader,

I am sharing the image that I worked on during the clear nights of October. After the Wizard nebula and the amount of details that I managed to get from one night I decided that I want to make a mosaic in the area. I chose the space between the Cave Nebula and the Lobster Claw due to the interesting cloud formations.

The data was acquired during the only four clear nights in October up to now. The image represents 2x2 mosaic - 1 part of the mosaic per night. I processed the data with the PhotometricMosaic script in PI. The script documentation states that it is not necessary to apply background extraction to the separate frames so I did not use DBE. However when I started to work on the mosaic I saw that the transition between frames was not seamless. I sourced the problem to the green and blue channels. Interesting thing is that my flats managed to fix the vignetting in the red channel but it remained visible in the blue and green. So I ran DBE on all the panels from the green and blue channels. After that the PhotometricMosaic script did its magic but it took me quite some time to extract the background gradients and vignetting. I am glad that I managed to fix this problem and gained additional knowledge on where to look if I see something like this in the future.

Processing wasn't easy for me. The Bubble Nebula and the small Lagoon Nebula are quite bright. I made a lot of tries not to burn the bright parts of the image and bring out all the other HA and dark cloud formations. I had some problems with star extraction which I managed to solve by extracting the stars from each channel separately. And I achieved the final result of my processing with the help of GHS. This stretching process for PI is just WOW!

During processing I had another idea. I imaged the Lobster Claw region back in Y2021. I thought that it would be great If I managed to integrate that data in the image as well. However when I compared the current data with the old one I decided not to bother as the old one was of lower quality. Back then I dedicated two nights and now this old material shows fewer faint details in comparison to the current one. Maybe back then I had imaged during a bright Moon or seeing wasn't good.

The objects in the image are situated on the border between Cepheus and Cassiopeia constellations. The annotated version shows the objects that I managed to capture. There are also some DSOs which are not in the catalogue of PI - patches of clouds near SH2-156. I managed to find them with the help of AladinLite and Simbad. These patches of HA are designated BFS 16, 18 and 19 - discovered in 1982.

Thanks for looking!

Clear skies!
Ivan