(IAAC) Obj: M33 - Inst: 20" f/4.3 dob, also naked eye


Observation Poster: Dave Bartolini <dbartolini@lucent.com>

Observer: Dave Bartolini
Your skills: Intermediate (some years)
Date/time of observation: Nov 7, 2001 11:00 EST
Location of site: Charlton, MA (Lat 42, Elev 800)
Site classification: Exurban
Sky darkness: 5.3 <Limiting magnitude>
Seeing: 5 <1-10 Seeing Scale (10 best)>
Moon presence: None - moon not in sky
Instrument: 20" f/4.3 dob, also naked eye
Magnification: 150x
Object(s): M33
Category: External galaxy. Extragalactic HII.
Constellation: Tri
Data: mag   size 
Position: RA :  DEC :
I tried for a while last night to detect M33 naked eye while it was nearly at zenith, and although my averted imagination may have caught a glimpse of it, I really can't claim to have seen it. I didn't think to try in binoculars, but based on the clarity of the sky last night, I believe that I would have been able to see it fairly easily. I was able to see M31 in and out with direct vision and it was obvious with averted vision. For stellar magnitudes, I was able to barely (but definitely) see 91 Pisces (mag 5.22) with direct vision. 

In a 20" at 150x, M33 showed a hint of spiral structure, especially the northern arm. The big H-II region (NGC604) looked like a separate galaxy. This is a big, dim galaxy. In my 10", the first time that I looked for it, I passed over it several times before I realized that I was actually looking at it! This is reported to be an object that if you can't see it in binoculars, you won't be able to see it in a telescope regardless of the aperture. I don't know if this is exactly true, but given it's minimal surface brightness, any significant light pollution will wash it out.

Optional related URLs: 
** This observing log automatically submitted via the Web from:
To stop receiving all 'netastrocatalog' lists, use the Web forms at: