(IAAC) Obj: NGC 4361 (Lawn Sprinkler nebula) - Inst: 10" fast dob

NOTE: David is not a current IAAC subscriber. So if you follow up,
please MANUALLY put 'KA0CZC@navix.net' in your reply's "Cc:" line!

Lew Gramer <owner-netastrocatalog@atmob.org>

Observer: David W Knisely
Your skills: Advanced (many years)
Date/time of observation: April 2000
Location of site: 
Site classification: Exurban
Sky darkness: Unknown
Seeing: Unknown
Moon presence: None - moon not in sky
Instrument: 10" fast dob
Magnification: 70x, 220x
Filter(s): None, DeepSky, UHC, OIII, Hbeta
Object(s): NGC 4361 (Lawn Sprinkler nebula)
Category: Planetary nebula.
Class: 3a+2
Constellation: Crv
Data: mag 10.3 13.18m*; size 45"/110" (round with halo)
Position: 12:24:30.8 -18:47:05
Well, I have FINALLY finished the Herschel II's (...sound of cheering,
applause from the gallery, catcalls, ect....).  While waiting for some
of the last galaxies to get into a better observing altitude at my dark
sky site, I decided to add a few more observations of nebulae for my
filter/nebulae survey (now up to 70 objects).  One which I  hadn't
observed in a while was the fair-sized planetary NGC 4361 in Corvus,
just over two degrees southeast of Gamma.  It was easily visible in my
ten inch at 70x  as a fuzzy oval spot with a brighter core and a diffuse
outer edge.  The Deep-sky filter helped the contrast slightly, but
otherwise, the object appeared the same as without a filter.  The UHC,
on the other hand, really made it stand out, revealing more of what
appeared to be a diffuse outer shell around a small oval core.  The OIII
filter changed the sky background to a jet black, and made the nebula
look better defined, although it also seemed a tad smaller than in the
UHC.  Of course, the H-beta more or less killed the object.  At 220x (no
filters needed), the object changed appearance somewhat.  At the core
was the faint central star, and surrounding it was a rather diffuse oval
ring-like shell with a glowing center imbedded in a diffuse outer haze.
This outer haze is what initially caused some confusion about the shape
of the inner shell, as this outer haze is somewhat patchy.  In fact,
there are two noticable patches: one off the northeast edge of the inner
ring, and another on the opposite side southwest of the ring.  Whenever
I used averted vision, the darn thing looked a little like a barred
spiral galaxy!  More direct vision just showed the inner oval ring-like
core.  I continued to be slightly confused by this until last night,
when a picture of the object on alt.binaries.pictures.astro showed the
full form.  The tufts of light in the outer shell do indeed look like
the ends of one of those old rotary lawin sprinklers, so I guess I
should dub this one, "the Lawn Sprinkler".  This should be a good object
for moderate apertures this time of year, so take a look and see the
"sprinkler".  Clear skies to  you.
David Knisely  KA0CZC@navix.net
Prairie Astronomy Club, Inc.  http://www.4w.com/pac
Hyde Memorial Observatory, http://www.blackstarpress.com/arin/hyde
*   Attend the 7th Annual NEBRASKA STAR PARTY   *
* July 29-Aug. 5th, 2000  http://www.4w.com/nsp *

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