Astrophotography by Keith B. Quattrocchi

NGC 6621 and 6622
Colliding  Galaxies in Draco
RGB/Ha Image
September 9, 2026

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Copyright 2026
Keith B Quattrocchi

Image Acquisition Information  
                    
Telescope: 16" RCOS Richey Chretien Telescope (ion milled at f/9) 
Camera: ZWO Full Frame Back Illuminated CMOS ASI 6200 MM
Guiding: Starlight Xpress AO with UltraStar Autoguiding Camera (AO control with PHD2).
Filters: Astrodon RBG, H-alpha, S-II and OIII Filters
Acquisition Programs: NINA, The SkyX, PHD2, PWI4
Processing Programs: PixInsight, RC Astro, Photoshop CS4
Date: Data processed on September 9, 2026.  Data acquisition:  August of 2021                           
Time:  Ha (5 min x 120) + RGB (5 min exposures x 120 for each filter) for a total of 40 hours.                
              
Image Information: ​NGC 6621 is an unusual  spiral galaxy in a dramatic cosmic collision with a smaller neighbor named NGC 6622.  Located nearly 300 million light-years away in the constellation Draco, these two galaxies came closest to each other about 100 million years ago.
This encounter pulled and stretched NGC 6621, wrapping a long, beautiful tail of stars and gas completely around its body. The intense gravity from the crash also squeezed the galaxy's gas clouds together, triggering a massive burst of new star formation that shines brightly between the two colliding worlds.
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Processing Information: These RGB + Ha images were obtained using AstroDon filters.  The RGB/Ha images were batch processed (calibrated, registered, normalized and integrated) in PixInsignt.   Further stretching, high pass filtering, background smoothing was performed with Adobe Photoshop CS/4 and PixInsight (including BlurXTerminator, GradXpert, SPCC, NoiseXTerminator). Within PixInsight the 3 main layers (extracted stars, Ha image, and RBG galaxy image) were obtained and then assembled (Photoshop Layers) and further processed in PhotoShop CS4.