Abell 21 or Madusa Nebula - reprocessed Sept. 2021
Below: A slightly wider view.
Abell 21 - Madusa Nebula
Above image awarded APOD GrAG 'Image of the Day' 10th January 2021
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
Original Resolution: 3692 x 2528
Dates: Dec. 15 - Dec. 25, 2020
Frames:
Astrodon Ha 5nm: 36x1200"
Astrodon OIII 5nm: 27x1200"
Astrodon RGB: 3x15x120"
Integration: 22.5 Hours
Center (RA, Dec): (112.146, 13.395)
Center (RA, hms): 07h 28m 35.131s
Center (Dec, dms): +13° 23' 41.190"
Size: 60.7 x 41.5 arcmin
Radius: 0.613 deg
Pixel scale: 0.986 arcsec/pixel
Orientation: Up is 278 degrees E of N
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
Original Resolution: 3692 x 2528
Dates: Dec. 15 - Dec. 25, 2020
Frames:
Astrodon Ha 5nm: 36x1200"
Astrodon OIII 5nm: 27x1200"
Astrodon RGB: 3x15x120"
Integration: 22.5 Hours
Center (RA, Dec): (112.146, 13.395)
Center (RA, hms): 07h 28m 35.131s
Center (Dec, dms): +13° 23' 41.190"
Size: 60.7 x 41.5 arcmin
Radius: 0.613 deg
Pixel scale: 0.986 arcsec/pixel
Orientation: Up is 278 degrees E of N
Sky Map
Annotated Image
