(IAAC) Obj: M33 (NGC 598) - Inst: 20" f4.4 Newtonian on Dobsonian mount


Observer: Nick Martin
Your skills: Intermediate
Date/time of observation: 10/18/1998  02.20 UT
Location of site: Bonnyton house drive, Ayrshire, Scotland
Site classification: rural
Sky darkness: 6.3 <Limiting magnitude>
Seeing: II-III <I-V Seeing Scale (I best)>
Moon presence: None - moon not in sky
Instrument: 20" F4.4 Newton on Dobsonian mount
Magnification: X186
Filter(s): None, Lumicon UHC
Object(s): M33 (NGC 598)
Category: External galaxy.
Class: Sc
Constellation: Tri
Data: mag 5.7  size 62' x 39'
Position: RA 01:34  DEC +30:39
M33 was conspicuous in the 7X50 finder. Using a 12 mm Nagler eyepiece in
the 20" the galaxy filled most of the field. For the first time when
(often) observing it, the galaxy showed clear spiral structure, distinct
spiral arms were visible. One arm extended from the barlike region S of
the nucleus to the bright H II region, NGC 604. Another arm goes out at
pa.100 curling round to pa.170, a third arm emerges at pa.110-120 and
curls round into a diffuse region about 1/2 field width S of the core. The
galaxy core shows a bright nucleus and resembles a barred spiral in the
core with a central bar running pa. 90 to pa. 270. At a pa.270 from the
core is another bright knot, another H II region. Other bright knots and
condensation were visible in the arms, one at pa.160 and about 1/3
eyepiece width out from the nucleus, another brighter region due S of
nucleus, 1/4 eyepiece width from it. At pa 180 a broad arm spreading out
round passing round the westerly (preceding) HII region before coming lost
in the diffuse background. The nebulosity extends about 2/3 eyepiece width
in E direction and about 1 eyepiece width northwards.  W and slightly
south there are definite condensations in the spiral arm, further round
there is another condensation about 1/3 width of Jupiter like a small
brighter patch about 15" across in the same arm.  The central core is
mottled and around the nucleus is a lobed brighter region. The HII regions
showed strong contrast when viewed through the UHC filter. This galaxy
really repays careful observation on a clear night.

Nick Martin, Bonnyton House, By Ayr, Ayrshire KA6 7EW ,Scotland, UK.
 Latitude 55 24'56" Longtitude 4 26' 00".
"Had I the heavens' embroidered cloths,
 Enwrought with golden and silver light,
 The blue and the dim and the dark cloths
 Of night and light and the half-light, ....." 
    He Wishes For The Cloths Of Heaven by W.B. Yeats