(IAAC) NGC 6857 - Newtonian 17.5" (445mm) F/4.5

Yann POTHIER yann.pothier at tiscali.fr
Sun Oct 28 13:13:35 EDT 2007


Observer: Yann POTHIER (France)
Your skill: advanced (many years)
Object: NGC 6857
Category: HII region, diffuse nebula
Constellation: CYG
Object data: Vmag=14.0, 40"x40" (4'x3')
RA/DE: 20h01m47.8s, +33°31'38" (2000.0)
Date and UT of observation: 10 august 2007, 23h40 UT
Location & latitude: La Clapiere Obs. (France, latN44 40 00, longE06 27 36)
Site classification: rural, alt.1650m (5500ft)
Limiting magnitude (visual in UMi): 6.31 (30% of the time)
Transparency (1 to 5 - best to worst): 1
Seeing (1 to 5 - best to worst): 2
Height above horizon: 30°
Moon up (phase?): no
Instrument: Coulter 445mm/17.5" F/4.5
Magnification: 80-426x
Filters used: OIII, UHC, Hbeta

Description: at 271x & 310x, with UHC filter, 
small nebula, of medium brightness, seen 
continuously with averted vision at 80x, observed 
from 80 to 426x, round although slightly 
triangular shape with NW apex; homogeneous with 
ill-defined edges; about 86" in diam., UHC and 
OIII filters give a good contrast gain, and even 
Hbeta shows a slight enhancement (rare enough to 
be mentioned); a mag.12.5 star is superimposed on 
the nebula, off-centered towards the N; this 
nebula was mistaken for a faint unresolved open 
cluster at low power.


-- 

Carpe noctem, Yann.

Yann Pothier
11 impasse Canart, 75012 PARIS, FRANCE
yann.pothier at fnac.net
http://www.astrosurf.com/cielextreme



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