(IAAC) FW: Sh2-242
Member National Deep Sky Observers Society (NDSOS), Webb Society, and
Association of Lunar and Planetary Observers (ALPO)
"Sight is a faculty; seeing, an art" - George Perkins Marsh
> -----Original Message-----
> From: DRiddle941@aol.com [mailto:DRiddle941@aol.com]
> Sent: Wednesday, January 27, 1999 8:27 PM
> To: firstname.lastname@example.org; email@example.com
> Subject: Re: Sh2-242
> Hi All
> Here are my thoughts on the Sh2-242 nebula(e) .
> The double entry in the Lynds' Bright Nebulae Catalogue may be due to a
> failure to recognize DG 84 and Sh2-242 as the same object . The
> original LBN
> catalogue cross references 826 as Sh2-242 and 827 as DG 84 . I
> speculate that
> a closer examination of the data may have caught the duplicated entry .
> A look at the original ( scanned ) Sharpless ' A Catalogue of
> HII Regions '
> ( ApJS , 4 , pg. 262 ) reveals that the 242 entry does indeed
> have a published
> diameter of 7' - this should eliminate the confusion over the 1 arc minute
> diameter quoted by Mr. Cragin . Without digging deeper , I assume
> that a typo
> crept into the online databases along the way .
> To confuse the issue , I noted that the scatter of published
> postions from
> the Lynds and DG ( MOL) positions fall along a roughly east to
> west line . A
> look at the RealSky image reveals the east side of the Sh2-242 nebula to
> contain a curving filament of dark nebulosity that appears to
> isolate a small
> ( 1'x2' ) glow from the main body of the nebula . I intially thought this
> might explain the double entries in the Lynds and DG catalogues and the 1'
> diameter in the Sh2 catalogue , but I can't make that theory hold water .
> This kind of detective work can be quite interesting at times
> - as long as
> I have a big bottle of Tylenol handy !
> Dave Riddle
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