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(IAAC) Obj: IC 434, Barnard 33 (Horsehead Nebula) - Inst: 4.5" f/7



[Sorry, Jeff, I was worried that this extraordinary observation might end
 up not being seen due to the Subject. I ENVY you those AZ skies! -Lew]
Observer: Jeff Medkeff
Your skill: expert
Date and UT of observation: 1998-Dec-31, 06:40 UT
Location & latitude: Sierra Vista, Arizona, 31N
Site classification: rural
Limiting magnitude (visual): 6.8 at 10 deg from zenith
Seeing (1 to 5 - best to worst): 2
Moon up (phase?): no
Instrument: 4.5" f/7 Newtonian
Magnification: 60x
Filters used: none
Object: IC 434 and Barnard 33 (Horsehead Nebula)
Category: bright and dark nebulosity
Constellation: Orion
Object data: ca. 39' MA IC 434; ca. 5 min. B 33
RA/DE: 5h 41m 0s -2d 23m 59s
Description:
I took careful notes at the observing site. I can think of nothing better
than to reproduce them verbatim here:
>>>>>
"Bright" nebulosity could be discerned cutting the 60x FOV approximately in
half along a line of stars [GSC-4771-1154, PPM 176000] extending from 50
Orionis and terminating several minutes past an aries-shaped telescopic
asterism [PPM 188350, GSC-4771-1034, GSC-4771-1047] which was superimposed
on the nebulosity. The edge of this nebulosity was pretty clearly visible
on the F side but was not readily detectable on the P side, as it tended to
fade into the sky background gradually rather than presenting a contrasty
edge. Using a black shroud, I could detect an indentation in the F side of
this nebulosity, but only during moments of good seeing (?) and good
relaxation. The indentation required averted vision. It was only observed
confidently and for longer periods after patching the observing eye for 20
minutes [i.e., keeping it in darkness for 20 minutes]. The horsehead was,
however, quite clearly seen after so doing, as a rounded 'bite' taken out
of the bright nebulosity. Subsequent comparisons of the memorized field to
photographic charts at the observing site showed the observed indentation
was consistent with the actual position of the dark nebulosity.
<<<<<
Shortly after taking these notes, I looked at the object with a 10" f/5
Newtonian, and found the horsehead to be a rather easily seen object that
posed no particular challenge. That observation wrt position and
orientation was consistent with the observation using the 4.5". This is,
incidentally, both my first posting to this list, and also my first
observation of the horsehead nebula. IMO the use of Hbeta filters on this
object in skies like I experienced should possibly be considered cheating. :-)
--
Jeff Medkeff          | If a little knowledge is a dangerous
Rockland Observatory  | thing, where is the man who has so much
Sierra Vista, Arizona | as to be out of danger? (T. H. Huxley)
On the web at http://shutter.vet.ohio-state.edu/