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(IAAC) Obj: NGC 4559 - Inst: 17.5" f/4.5 dob



[Old but apropos, now that Coma is back "in range" in the early AM sky!]
Observer: Lew Gramer
Your skills: Intermediate (some years)
Date/time of observation: 30 Apr 2000, 00:00 LMT
Location of site: ATMs of Boston Clubhouse, Westford MA USA (42oN)
Site classification: Exurban.
Sky darkness: 6.0 <Limiting magnitude>
Seeing: 6 <1-10 Seeing Scale (10 best)>
Moon presence: None - moon not in sky
Instrument: 17.5" f/4.5 dob
Magnification: 57x, 90x, 220x, 285x
Filter(s): None
Object(s): NGC 4559
Category: External galaxy.
Class: SAB(rs)cd II-III
Constellation: Com
Data: mag 10.01  size 10.72x4.37
Position: 12:35:57 +27:57:53
Description:
This large, lovely galaxy was readily found at 57x, by using a pretty
arc formed by the naked-eye stars gamma, 14, 16 and 17 Com. Imagining
this arc of stars as showing a cross-section of a telescope mirror, I
located n4559 roughly at the "focal point" of this "mirror": it can be
seen as the E vertex of an equilateral triangle formed with two mag 9
stars in the "focal area". Once found, the galaxy was stunning in that
it yielded more and more rich detail, the greater the power applied to
it! First impression was of a very tight, bright core, surrounded by a
considerably diffuse halo. At 220x, this core was obviously elongated
E-W, somewhat skewed from the halo's less pronounced elongation. But a
surprise awaited me at higher power: with 285x the inner core suddenly
began to display a more irregular shape, reminding me variously (as the
seeing varied from second to second) of a peanut, an arc, or an "X" or
criss-cross shape. I also noted at all powers a distinct "edge" to the
halo in the South and East, with additional halo beyond this edge only
suspected at higher powers. And at both 220x & 285x, tiny mottlings or
"stellarings" (Brian Skiff's term) were suspected suffusing the outer
core and the halo, S, N, E and W. Finally, 285x showed a tiny stellar
nucleus, highly dependent on seeing and averted vision.
--
When I next get a look at this object under good conditions, I would
love to apply some filters to the high power view, to try to confirm
(and log in detail) the intriguing "stellarings" I noted that night!
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