Abell 21 - The Medusa Nebula (SH2-274) (Frank Colosimo)

Celestial hemisphere: Northern · Constellation: Gemini (Gem) · Contains: PK205+14.1 · Sh2-274

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Abell 21 - The Medusa Nebula (SH2-274)

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Abell 21 - The Medusa Nebula (SH2-274)

Abell 21, aka SH2-274 or the Medusa nebula in Gemini is a fairly low-brightness planetary, but large for a planetary at 10 arc minutes. It is about 1000 light years away.

It was discovered fairly recently, in 1955.

Imaging data:

Date: Jan 7 2021 - Feb 10 2021, Jan 2009

Location: New Ringgold PA

Optics/Camera (Luminance): Starizon Hyperion 12.5 inch and SBIG STL-11000

Optics/Camera (Color): Celestron Edge HD 11 and ZWO ASI1600MM-Cool

Mount: Paramount ME and Paramount MX

Exposure: Luminance: 46x15 minutes, R:17x8 min G:16x8 min B:13x8 min HA:33x10 minutes OIII:51x10 minutes for a total of 31.6 hours, 176 subs at avg 647 sec (plus some additional color data from 2009)

Processing: Image acquisition using CCD Autopilot. Initial processing was done using Maxim DL with subsequent processing with Photoshop. HA data was added to the Luminance and Red channel, while OIII was added to the Blue.

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Status	Advanced success
Started	...
Astrometry.net job	4403588
PixInsight job	NI0K7GWBXKRF97HN7CDH31XU2UCJ1IQU
PixInsight queue size	n/a
PixInsight stage	n/a

RA (center)	07h29m00s.666
RA (top/left)	07h30m03s.443
RA (top/right)	07h27m57s.456
RA (bottom/right)	07h27m57s.978
RA (bottom/left)	07h30m03s.772

Dec (center)	+13°14′43″.49
Dec (top/left)	+13°26′22″.12
Dec (top/right)	+13°26′13″.90
Dec (bottom/right)	+13°03′04″.41
Dec (bottom/left)	+13°03′12″.79

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Abell 21 - The Medusa Nebula (SH2-274)

Abell 21 - The Medusa Nebula (SH2-274)

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Abell 21 - The Medusa Nebula (SH2-274)

Abell 21 - The Medusa Nebula (SH2-274)

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