For that I choose the Abell 2256 cluster in Ursa Minor. It's a cluster that's captured very, very rarely.
Abell 2256 has around 500 galaxies in it and is at around 800 million lightyears. It was thought to be just another galaxy cluster, yet studies with radio telescopes show a different story.
Like the studies with the LOFAR (Low Frequency Array) shows that Abell 2256 most likely is formed out of collisions and mergers of smaller clusters. This leaves a kind of radio signature like the one that can be seen here: https://aasnova.org/2022/05/02/featured ... bell-2256/
I couldn't capture really deep due to the fact that nights here at the moment are not really dark. Still a nice result.
I also made a negative, b/w version with annotations. For this I used the annotation feature of Sharpcap. This shows galaxies up to MAG18 but I checked in Aladin with the NED catalogue and the faintest one showing is MAG21.3.
I platesolved a single sub and used the annotation feature. I then dialed the Display Histogram totally down, leaving only the annotations and some stars. This I saved as image and used in Photoshop as layer with Screen. Since all but the annotations was black, it acted as a nice transparent layer
![Smile :)](./images/smilies/icon_e_smile.gif)
Altered the overal color from orange to blue for better viewing.
The 3000x2044px color version can be seen here: https://i.ibb.co/ZY0MNDP/Abell2256-RGB.jpg
The negative, b/w annotation 4048x2758px version here: https://i.ibb.co/NNNBQ9R/Abell2256-bw-ann.jpg
![Image](https://i.ibb.co/ZY0MNDP/Abell2256-RGB.jpg)
![Image](https://i.ibb.co/NNNBQ9R/Abell2256-bw-ann.jpg)
Bortle 6/7
Meade LX200 8" f/10 ACF OTA
Ioptron CEM25EC mount (no guiding)
Baader IR/UV Cut filter
Zwo ASI071MC Pro camera
Captured with SharpCap Pro @ -10 Celsius / White balance R50 B50
22 x 180sec / Gain 90 / Offset 4
26 x 300sec / Gain 90 / Offset 4
20 x darks, 50 x flats and 50 x darkflats per set
Stacked with SiriL and Sirilic
Processed with Siril and Photoshop
Siril: Crop, Photometric Color Calibration, Background Extraction, Histogram
Photoshop: Camera Raw Filter (white balance, lights, contrast, color saturation, clarity, vignette), noise reduction with NoiseXterminator plug-in.