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(IAAC) Obj: Abell 1656 (Coma Cluster, AGC 1656, IC 3955, NGC 4864, NGC 4867, NGC 4869, NGC 4874, NGC 4889, NGC 4898) - Inst: 16" f/4.45, Newtonian dob, with tracking



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Observation Poster: Don Clouse <dlcdeepsky@insightbb.com>
Observer: Don Clouse
Your skills: Intermediate (some years)
Date/time of observation: March 13, 2004, 05:30 UT
Location of site: southern Indiana, USA (Lat 38 N, Elev )
Site classification: Rural
Sky darkness: 7 <1-10 Scale (10 best)>
Seeing: 8 <1-10 Seeing Scale (10 best)>
Moon presence: None - moon not in sky
Instrument: 16" f/4.45, Newtonian dob, with tracking
Magnification: 172x
Filter(s): none
Object(s): Abell 1656 (Coma Cluster, AGC 1656, IC 3955, NGC 4864, NGC 4867, NGC 4869, NGC 4874, NGC 4889, NGC 4898)
Category: Cluster of galaxies.
Class: 2 1 II
Constellation: Com
Data: mag 10: 13.5  size 224'
Position: RA 13h:00m  DEC +27d:58m
Description:
All observations are at 172x (10.5mm Pentax XL) with a calculated true field of
view of 23'.  Above and Gx data are from MegaStar5.  After writing a brief 
description of AGC 1656, I spent about 30 minutes sketching the field. Then,
from 06:00 to 06:30 UT, I wrote the galaxy descriptions.  It was a very 
transparent night at our club's dark site.  I was amazed to see not one, but
two mag 15.4 gx's, shattering my previous record of 15.0!  In hindsight, I feel
that I could have seen a few more gx's with a little more time and effort...
AGC 1656 - 05:30 UT - Seven galaxies are visible in a span of 18' with one,
IC 3955, requiring averted vision to be seen.  The gx's are scattered over the
field, however NGC's 4864 & 4867 are very close at < 1' apart.  The two main 
gx's, 4889 & 4874, are quite obvious, with 4889 appearing much brighter.  The
other five were not seen immediately, but revealed themselves upon closer
scrutiny.
NGC 4898 - 06:05 UT, 14.5b, E pec, 0.5'x0.5' - Visible with direct vision as a 
very faint, slightly elongated smudge.  No other detail visible.
NGC 4889 - 06:08 UT, 12.5b, E+4, 2.8'x2.2' - Approximately 1' in size, elongated
3/2 with a brighter core surrounded by an even haze.
NGC 4874 - 06:11 UT, 12.6b, E+0, 2.3'x2.3' - Easily seen but dimmer than 4889.
The core is just bit brighter than the surrounding haze, which fades rapidly.
NGC 4869 - 06:14 UT, 14.8b, E3, 0.7'x0.7' - Detectable with direct vision as a 
a small, very faint smudge.  Averted vision reveals a tiny, near stellar core
surrounded by an indistinct haze.  A faint star (mag 14.5 GSC 1995:2012)is 
immediately adjacent to 4869.
NGC 4867 - 06:20 UT, 15.4b, E3, 0.6'x0.5' - A tiny, featureless spot.  However,
a brighter center is seen with averted vision.
NGC 4864 - 06:22 UT, 14.6b, E2, 0.7'x0.7' - Brighter and larger than its close
companion, NGC 4867.  Like 4867, averted vision reveals a brighter center.
Otherwise, this gx appears featureless.
IC 3955 - 06:25 UT, 15.4b, SA0, 0.6'x0.4' - Requires averted vision to be seen.
It has a roundish, but featureless shape and (contrary to the catalog sizes) 
appears larger than NGC 4864.
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