Image Description and Details :

Abell 21 is a planetary Nebula that was discovered and catalogued as such, in 1955, by George Abell. Abell 21 is a planetary Nebula that was discovered and catalogued as such, in 1955, by George Abell. This image was taken with narrowband filters (Ha, OIII and NII). NII was added because some planetaries have distinct NII signals. In this case, the NII emission was similar to the Ha emission. Total exposure 31h 40m. Telescope 24 inch f/6.5 reflector, located in NMSkies, Mayhill, New Mexico. Processing: CCDStack and Photoshop CC 2021.

Copyright: Josep Drudis