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Re: (IAAC) Obj: pyxis globular - Inst: 20" ff4



> Andrew, yet again your observation was stimulating - not to say tantalizing for
> us Northerners! :) The only additional information I can provide on the Pyx GC
> is from Jeff Bondono's 'dObjects' database, where it is listed as containing
> brightest stars of photographic magnitude 17.5, and having size 2'!
> 
> BTW, note that this object SHOULD be visible to observers from the Southern
> United States at the appropriate times in the late Fall and Winter. With an
> unusually low surface brightness though (for a GC), it would be a challenge.
> 
> Has anyone observed it from the Continental US or similar latitudes?
> 
Lew,
Jay McNeil and I observed the Pyxis Globular a couple of years ago from
Columbus Texas in my 20".  And it has been observed from the Winter Star
Party in the Florida Keys as well. My notes from 2-15-97 at 1:10 AM on a
night of 7 of 10 seeing conditions indicate it was faint but clearly
visible as a round evenly illuminated 1' glow with no resolution even at
450 power in my 20" f/4.  It is enclosed within a sideways "V" shaped
asterism of stars.  Listed magnitude is 12.9. the horizontal branch
magnitude of the stars is 19.25 and as you mentioned Lew, the brightest
star is 17.5
Below is the discovery abstract for the Pyxis Cluster:
Barbara Wilson
_________________________________________
The Pyxis cluster: a newly identified galactic globular cluster
Authors:            DEMERS, SERGE; IRWIN, M. J.; KUNKEL, W. E.
Affiliation:       AA(U. de Montreal), AB(RGO), AC(OCIW)
Journal:            Bull. American Astron. Soc., 186, #49.06
Publication Date:05/1995
Origin:        1995: American Astronomical Society
Bibliographic Code: 1995BAAS..186.4906D
 Abstract</h3>
In a recent paper Weinberger (1995 PASP 107 58) produced a catalogue of
several new interesting objects discovered from a systematic search
ofsky survey plates.  One of these objects appeared to just resolve
intostars at the plate limit, suggesting it might be a previously
unknown
distant Galactic satellite.  We carried out a preliminary
investigationof this object using UKST Bj and R sky survey copies of the
regiondigitised with the APM facility in Cambridge.  The object just
resolved into stars on both digitised plates supporting the idea that it
is either a distant star cluster or even a small dwarf spheroidal
galaxy. To investigate this object further we obtained deep CCD images
in B, R and I on the Du Pont telescope at Las Campanas during March
1995.  A B,R
CMD to R=23 reveals a well defined main sequence with a turnoff at
R=21.5.  A sparsely populated sub-giant branch leads up to a horizontal
branch at R=18.8. Assuming a reddenning of E(B-V) = 0.27 read from the
maps of Burstein & Heiles (1982 AJ, 87, 1165) and a horizontal
branch
magnitude of M_R = 0.2 gives a true distance modulus of ~ 18.0 and hence
a distance of 40 kpc. The cluster of stars is some 2 arcmin in core
size, or 23 pc if it is at a distance of 40 kpc.
 The object lies in the constellation of Pyxis and we propose to call it
the Pyxis ``globular'' cluster.  It is similar in morphological
appearance to the outer halo Pal globular clusters.  Interestingly, the
Pyxis cluster lies close to the plane of the Magellanic Clouds orbit
(Jones et al. 1994) and might be a detached cluster of this system. A
radial velocity is urgently needed to examine this possibility.<p>
 We will present further analysis of our data at the meeting, including
better reddenning estimates from the B,R,I data, an age estimate
obtained by fitting to the revised Yale isochrones and an analysis of
the cluster morphology from structure counts of detected images.
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