NGC/IC Project Restoration Effort
(This is a very very beta version)
NGC7175
Basic Information
Location and Magnitude
Right Ascension: 21:58:50.0
Declination: +54:31:30
Constellation: CYG
Visual Magnitude:
Historic Information
Discoverer: Herschel J.
Year of discovery: 1829
Discovery aperture: 18.3
Observational
Summary description: Cl, vL, pRi, lC
Sub-type: *Grp
Corwin's Notes
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NGC 7175 is probably part of the Milky Way. JH's position applies to "The
chief * 9 m of a vL, loose clustering group which fills two fields, and is
pretty rich of large stars." Checking the POSS1, I see such a grouping of a
few dozen stars, roughly 30 arcmin by 20 arcmin, oriented pretty much east-
west, and centered about 3 arcmin southwest of JH's 9th magnitude star.
I've also checked the sweep (number 212 on 25 Sept 1829) in the Herschel
Archives. The page is faint (aside from the reduced position which comes
through as strongly as usual -- it agrees with JH's published position) but
insofar as I can make out the handwriting, the information there suggests that
JH's position reduction is correct.
However, about 30 arcmin south is a smaller, sparcer, but much more obvious
clustering of brighter stars. Years ago, I suggested that this might be JH's
object. It is much too small, though, to "fill two fields" (30 arcmin), and
JH's position is very close to the bright star he mentions in his sweep. So,
while his object is less obvious on the POSS (and DSS), it is almost certainly
the one he saw.
Jaakko Saloranta independently suggested to me in October 2010 that the
cluster to the south might be NGC 7175. He further pointed out that the
southern object has been found to be a real cluster (see Karchenko et al, A&A
440, 403, 2005 where this is number 116). While this might be a candidate for
JH's object, the objections I note above suggest that it is not.
Nevertheless, I've put the new cluster in the main table with a query. Note,
too, that Karchenko et al put it about 10 arcmin closer to JH's position than
I did.
In summary, then, the fields are only candidates for JH's object. We may need
some more work visual work on this, and a look at the original pages of the
sweep.
Steve's Notes
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NGC 7175
17.5" (10/25/97): at 100x there is no noticeable clustering at the John Herschel's position centered on a mag 9 star at 21 58 51.5 +54 49 01. Visually, this appears to be a rich Milky Way field over unresolved haze.