|Abell 51: Planetary Nebula (Sagittarius) RA: 19h 01.0m / DEC: -18° 12'.2|
Instrument: 18-inch Obsession
Abell 51 is conveniently located adjacent to a Y-asterism of four 10th to 12th magnitude stars. The planetary nebula is centered in my sketch, which was made at 173X. Directly visible unfiltered in the big Obsession, I also tried UHC and OIII filters and preferred the OIII as providing a noticeably improved view. The planetary covers a 1' diameter patch of sky, the outer portion--particularly that to the east--appearing brighter than the inner. The 15.4 magnitude central star is not seen. But some 50-odd stars field stars are. The Y-asterism is clearly seen west of Abell 51, which has a published photographic magnitude of 15.4.
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Revised: July 9, 2005 [WDF]