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(IAAC) Obj: NGC 2261 - Inst: TV-102 (102mm f/8.6 APO refractor)



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Observation Poster: Ron B[ee] <ronby@home.com>
Observer: Ron B[ee]
Your skills: Beginner (< one year)
Date/time of observation: 12/19/01 10:30PST
Location of site: 117h 9m W (Lat 32h 43m N, Elev 2000 ft)
Site classification: Exurban
Sky darkness: 5 <Limiting magnitude>
Seeing: 5 <1-10 Seeing Scale (10 best)>
Moon presence: None - moon not in sky
Instrument: TV-102 (102mm f/8.6 APO refractor)
Magnification: 22x, 30x, 60x, 110x, 146x, 176x, 220x
Filter(s): none
Object(s): NGC 2261
Category: Reflection nebula.
Class: 
Constellation: Mon
Data: mag 10  size 2'
Position: RA :  DEC :
Description:
The TV-102 found the Hubble's Variable Nebula with the 30mm Celestron
EP (30x) and looked like a dim nebulosity. At 60x, the nebula becomes 
interesting. But with the PN catcher, the 8mm TV Radian (110x) really
revealed its true shape and looked to me like a comet with a fan-shape
tail and a bright "coma"; the "coma" is of course the variable star R Mon. 
The nebula forms a triangle with the 10.2 mag star GSC 746:1024
(HD 261389) and 12.3 mag star GSC 746:742. R Mon. seems to be close
to the brightness of the 12.3 mag star GSC 746:742. The "tail"
seems to be pointed at a couple of stars that looked like a double:
GSC 746:1366 and GSC 746:589. The "coma" is now quite bright because
of the increased contrast. The fan-shape nebula is brighter at 60x,
but 8mm (110x) yields more contrast and a better view. I did not 
expect to use higher magnification, but read on...
The 6mm Radian (146x) gives a better view but slightly dimmer. The
most surprising view came at 176x (5mm Tak LE) because lo and behold
the shape really looks very much like the photographs you can find
on the web, except that it looks a lot dimmer through the TV-102 than
the photos! The fan-shape tail is quite evident at this magnification
and the "coma" is still bright. Even at 220x (4mm Radian), the
complete shape of the nebula is still quite evident, albeit dim
now with R Mon. maintaining its brightness.
Later, I consulted the old master, Burnham and he wrote "...the 
nebula can be studied under fairly high powers since the surface 
brightness is high. A bluish color is evident in large instruments.
R Monocerotis itself, however, is very often difficult object to 
observe, and is frequently lost in the bright glow of the nebula."
Well, the TV-102 light cup did see only gray color, but it saw R
Mon. quite well ;-).
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