(IAAC) Obj: M 101 - Inst: 15" f4.5 Obsession

**anonymous@s15272250.onlinehome-server.com**

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Observation Poster: Armin Hermann <burmeseinn@yahoo.com>

Observer: Armin Hermann
Your skills: Advanced (many years)
Date/time of observation: 22 Feb 2004
Location of site: Sangkhlaburi / Thailand (Lat +15, Elev 200)
Site classification: Exurban
Sky darkness: 5.5 <Limiting magnitude>
Seeing: 9 <1-10 Seeing Scale (10 best)>
Moon presence: None - moon not in sky
Instrument: 15" f4.5 Obsession
Magnification: 131x, 244x, 342x
Filter(s): none
Object(s): M 101
Category: External galaxy.
Class: 
Constellation: UMa
Data: mag 8.1  size 28'
Position: RA 14:03  DEC +54:
Description:
M101 is a difficult object in any scope. Very clear skies are needed to show the 
spiral structure easily. At 131x, M101 does fit into the whole FOV! The bright, 
small core (approx 1') is surrounded by an inner halo and further by the faint outer 
halo that resolves into spiral arms when observed with averted vision. At 244x and 
342x several faint and tiny patches of light become visible within the spiral arms.  
The faint knots within M101 look a little bit like 13 or 14mag planetaries or faint 
galaxies with diameters of just 1' - or often just 20-30". M101 definitely an easier 
object in large binoculars due to its extremely low surface brightness of 14.8

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