Abell 21 - Medusa Nebula
Another view below (Also see 2020 version HERE )
See my 2020 version HERE
The Medusa Nebula is a large planetary nebula in the constellation of Gemini on the Canis Minor border. It also known as Abell 21 and Sharpless 2-274. It was originally discovered in 1955 by UCLA astronomer George O. Abell, who classified it as an old planetary nebula.
Until the early 1970s, the Medusa 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 big, its surface brightness is very low, with surface magnitudes of between +15.99 and +25 reported. Because of this, most websites recommend at least an 8-inch (200 mm) telescope with an OIII filter to find this object although probably possible to image with smaller apertures.
It was indeed a struggle to image it with my 4" refractor.....and it needs so much more time than I have given it here. It is more or less gone for this year; perhaps next year I can add to this and try bring out a little more detail.
An interesting piece in Astronomy Now: https://astronomynow.com/2015/05/21/the-dreadful-beauty-of-medusa/
Imaging telescopes or lenses: Takahashi FSQ106ED
Imaging cameras: QSI 6120i
Mounts: Takahashi EM 400 Temma 2M
Guiding telescopes or lenses: Takahashi FS60CB
Guiding cameras: QHY CCD QHY 5 II
Software: PHD 2, Pleiades Astrophoto PixInsight , Sequence Generator Pro SGP
Filters: Astrodon 5nm Ha, Astrodon 5nm OIII
Accessories: Robofocus Focuser, ATIK EFW2
Original Resolution: 3336 x 2192
Dates: 5th - 22nd Apr. '17
Frames:
Astrodon 5nm Ha 22 x 1200"
Astrodon 5nm OIII 19 x 1200"
Integration: 13 Hours 40 Min
Center (RA, Dec): (112.254, 13.253)
Center (RA, hms): 07h 29m 01.050s
Center (Dec, dms): +13° 15' 10.925"
Size: 67 x 44.1 arcmin
Radius: 0.668 deg
Pixel scale: 1.21 arcsec/pixel
Orientation: Up is -89.4 degrees E of N
Until the early 1970s, the Medusa 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 big, its surface brightness is very low, with surface magnitudes of between +15.99 and +25 reported. Because of this, most websites recommend at least an 8-inch (200 mm) telescope with an OIII filter to find this object although probably possible to image with smaller apertures.
It was indeed a struggle to image it with my 4" refractor.....and it needs so much more time than I have given it here. It is more or less gone for this year; perhaps next year I can add to this and try bring out a little more detail.
An interesting piece in Astronomy Now: https://astronomynow.com/2015/05/21/the-dreadful-beauty-of-medusa/
Imaging telescopes or lenses: Takahashi FSQ106ED
Imaging cameras: QSI 6120i
Mounts: Takahashi EM 400 Temma 2M
Guiding telescopes or lenses: Takahashi FS60CB
Guiding cameras: QHY CCD QHY 5 II
Software: PHD 2, Pleiades Astrophoto PixInsight , Sequence Generator Pro SGP
Filters: Astrodon 5nm Ha, Astrodon 5nm OIII
Accessories: Robofocus Focuser, ATIK EFW2
Original Resolution: 3336 x 2192
Dates: 5th - 22nd Apr. '17
Frames:
Astrodon 5nm Ha 22 x 1200"
Astrodon 5nm OIII 19 x 1200"
Integration: 13 Hours 40 Min
Center (RA, Dec): (112.254, 13.253)
Center (RA, hms): 07h 29m 01.050s
Center (Dec, dms): +13° 15' 10.925"
Size: 67 x 44.1 arcmin
Radius: 0.668 deg
Pixel scale: 1.21 arcsec/pixel
Orientation: Up is -89.4 degrees E of N
Sky Plot
Annotated Image
