Abell 21 – Medusa Nebula

The Medusa Nebula is a planetary nebula in the constellation of Gemini. It is also known as Abell 21 and Sharpless 2-274. It was originally discovered in 1955 by University of California, Los Angeles astronomer George O. Abell, who classified it as an old planetary nebula. Until the early 1970s, the nebula was thought to be a supernova remnant. With the computation of expansion velocities and the thermal character of the radio emission, Soviet astronomers in 1971 concluded that it was most likely a planetary nebula. As the nebula is so large, its surface brightness is very low, with surface magnitudes of between +15.99 and +25 reported.

Imaging telescopes or lenses: Takahashi FSQ130ED
Imaging cameras: QSI 6120i
Mounts: Takahashi EM 400 Temma 2
Guiding cameras: QHY CCD QHY 5 II
Software: PHD 2, Astro Pixel Processer, PixInsight , Sequence Generator Pro SGP
Filters: Astrodon R,G,B, OIII (5nm) & Ha (5nm)
Accessories: ATIK EFW2

Dates: Dec. 15 – Dec. 25, 2020
Astrodon Ha 5nm: 36×1200″
Astrodon OIII 5nm: 27×1200″
Astrodon RGB: 3x15x120″
Integration: 22.5 Hours

Autore: Brendan Kinch (sito)