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Re: (IAAC) Obj: Sanduleak 2-21 - Inst: 40" f/5 dob
I think this object was known but as a galaxy before 1975. It had a listing
in the MCG as MGC 3-21-4. The problem with re-identifying it as a PN comes
from it being rather close to a bright star ( see the DSS/RealSky image ).
There also a lot of faint galaxies around. I guess an emission line survey
picked it up as strange for a galaxy.
At 02:54 22/01/2000 -0500, you wrote:
>----
>
>Observer: Mark G.Birkmann
>Your skills: Intermediate (some years)
>Date/time of observation: 1/14/2000, 8:10 UT, 2:10 CST
>Location of site: New Haven, Missouri (Lat ~38, Elev ~700 feet)
>Site classification: Rural
>Sky darkness: 5 <1-10 Scale (10 best)>
>Seeing: 6 <1-10 Seeing Scale (10 best)>
>Moon presence: None - moon not in sky
>Instrument: 40" f/5 dob
>Magnification: 235, 470
>Filter(s): orion ultrablock
>Object(s): Sanduleak 2-21
>Category: Planetary nebula.
>Class:
>Constellation: Pupis
>Data: mag 13.6 size 40"
>Position: RA 8:8m 44s DEC -19:14'
>Description:
>This planetary is easily found 4' west of the 4th mag. star 16 pupis. At
235x
>it was faint, but visible with direct vision. With the Orion Ultrablock
filter
>the nebula appeared very bright and somewhat larger, even with 16 pupis in
the
>field of view. The nebula was grey, had a uniform surface brightness, no
hint
>of structure or of a central star, and had indistinct edges. Interestingly,
>Steve Gottlieb noted in the autumn 1998 issue of DeepSky that for some unkown
>reason this nebula wasn't identified until 1975. This would be
understandable
>if it were only visible in very large scopes but he reported it as easily
>visible in his 13.1" scope with OIII filter. If this object escaped
detection
>for so long might there be other? A drawing can be seen at
>http://www.fortunecity.com/greenfield/twyford/637/drawings.htm
>--
>Optional related URLs:
http://www.fortunecity.com/greenfield/twyford/637/drawings.htm
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