Instrument

Celestron C11 @  F/6.1 (1705 mm)  1.087 arcsec / pixel

Mount

Losmandy G11

Camera

SBIG ST-7 with CFW-8A color wheel

Acquisition Data

8/6/2006 & 8/11/2006  Near downtown Seattle

Exposure

Lum     90 min  (18 x 5 min)
Red     60 min  (12 x 5,     bin 2 x 2)
Green  60 min  (12 x 5,    bin 2 x 2)
Blue    60 min  (  8 x 7.5, bin 2 x 2)

Software

CCDSoft, FocusMax, PhotoShop CS, Auto-Dither was used to dither the luminance layer.

Comment

Discovered 1745-46 by Philippe Loys de Chéseaux.

M71 is at a distance of about 13,000 light years from Earth and spans some 27 light years.

M71 was long thought (until the 1970's) to be a densely packed open cluster.  Modern photometric photometry has detected a short horizontal branch in the H-R diagram of M71, which is characteristic of a globular cluster.  So today, M71 is designated as a very loosely concentrated globular cluster.

North is to the right.