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(IAAC) Obj: M 77 Group (Galaxy Group) - Inst: 20" f/5 dob newt



Observer: Lew Gramer
Your skills: Intermediate
Date and UT of Observation: 1997-11-04/05, 05:15 UT
Location: Miles Standish State Forest, MA, USA (41N, elev 30m)
Site classification: rural
Limiting magnitude: 6.9 (zenith)
Seeing: 4 of 10 - above average
Moon up: no
Instrument: 20" f/5 Tectron truss-tube dob Newtonian reflector
Magnification: 70x, 210x, 420x
Filters used: None
Object: M77 Group (or NGC 1068 Group)
Category: Galaxy Group (NOT gravitationally bound?)
Constellation: Cet
Data: mag 8.9 (brightest eg)  size 120'x120'
RA/DE: 02h42m  -00o01m
Description:
Tonight's observing session became the Night of the Galaxy Fields,
as Steve Clougherty and myself swung from one Abell cluster, non-
Abell cluster, or galaxy group to another. The third target Field
of the night was the group of galaxies associated with bright and
lovely Messier 77 in Cetus. This is a broad, weakly concentrated
group easily accessible to smaller deep-sky scopes. Its interest
consists in the richness of galaxies within only a few wide eye-
piece fields, and in the diversity of their spiral morphologies.
(Although this IS cataloged as a group, the scatter of recession
velocities makes me believe most of these galaxies are unrelated.)
--
  M77 ngc1068   mag 8.9         size 7.1'x6.0'  type (R)SA(rs)bP
M77 can be readily found under even suburban light pollution, just
1o ESE of delta Ceti in the neck of the Monster. This bright blob
forms a nice triangle with delta and with naked-eye 84 Cet (mag 6)
to the SW. I only used M77 tonight as a locator object tonight for
the grouping which bears its name, and so did not savor its finest
details. But I did stop to note the classically-shaped spiral arms
raying N and S out of its bright, tiny little core; some mottling
visible in the halo to E and W; and what seemed to me an outer arm
or ring of slightly increased brightness bounded the haze to the E.
--
  ngc 1055      mag 10.6        size 7.6'x2.7'  type SBb:sp II-III
Next to M77, probably the brightest member of this Group. In a wide
field (70x, 55'), ngc1055 seems a pretty averted-vision echo of its
brighter Messier neighbor nearby to the S. At higher power however
(210x, 23'), it appears quite different, showing a smallish, bright
central nub to direct vision, wrapped in an outer haze which extends
roughly E-W. To the N the core is distincly irregular, with a sharp
edge along its Nern extent, and a second core or extension just NW.
(Viewing a DSS image later, I interpreted that sharp edge to be the
lower bound of n1055's central dark lane. But the core extension??)
--
  ngc 1072      mag 14.2p       size 1.5'x0.5'  type SABb
NGC1055 and NGC1072 are the only members of M77's Group actually
visible in the same wide-angle field with M77 itself. This tiny
galaxy was marked on my atlas (Harald&Bobroff's _AstroAtlas_) as
lying about 30' due N of the mighty Messier. A search turned up
nothing, but thanks to more detailed charts I had on hand for my
supernova search, I found it - and noted nothing with averted
vision but a slightly non-stellar core, no halo, and no detail...
--
  ngc 1073      mag 11.0        size 4.9'x4.5'  type SAB(rs)c II
The most isolated member of the Group, lying some 1.5o N of M77.
NGC1073 required averted vision at 70x, lying just off the N apex
of a pretty "arrow-head" grouping of mag 9-11 stars "flying" N.
In spite of its supposed brightness, details only became visible
to me at 210x with highly concentrated vision. It first appeared
as a faint "spindle" elongated roughly E-W. But under momentary
ideal conditions, I could spot a broad, irregular N-S halo, with
one subtle small "tip" spiralling out SW of what I later surmised
to be an E-W bar. Surprising (and probably hard to repeat) seeing
such detail in a low surface-brightness, loose-wrapped face-on.
--
  ngc 1087      mag 10.9        size 3.7'x2.2'  type SAB(rs)c III
NGC1087 is much the brightest of a little trio of outliers that
are about 1o E of M77. A stellar, averted-vision nucleus lies at
center, enveloped in an averted-vision halo lacking further detail.
--
  ngc 1090      mag 11.8        size 4.0'x1.7'  type SB(rs)bc IV
Lying to the N of n1087 in the same medium-power field, this is
essentially just a nearly-stellar core, with the merest hint to
averted vision of an extended halo spreading NW and SE.
--
  ngc 1094      mag 13.4p       size 1.3'x1.0'  type SABab
This final companion was JUST visible to averted vision as a tiny
non-stellar "spot" immediately S of a mag 11 field star.
--
Having spent considerable time on the individual galaxies of this
group, I began to prepare myself for the final Galaxy Glob of the
night - in many ways, a "chestnut", which I saved for last to top
off the session: Abell 426 in Perseus! (See later observing log.)