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NGC 6822, Barnard's Galaxy, in Sagittarius is an irregular member of the Local Group of galaxies.  Located just 1.5 mln light years away, this galaxy is distinguished by the number of HII regions, or emission nebulae, it contains.  The most well known of these, known as Hubble V is visible top centre right as a small bright area flaring to the right.  Other nebula are just visible to the top right of the image and to the left of Hubble V.

Image info

Telescope:  Skywatcher 8" f/5 Newtonian

Focus:  Prime focus

Camera:  SAC7B, uncooled

Exposure:  Mosaic of 2 images each 100 & 99 x 25s 

Date:  27th July 2003

Processing:  The usual YRGB processing, with the subtraction of a 'banding flat' (see the Advanced Processing page) to remove fine banding noise from both images in the mosaic.


A very challenging subject, with low surface brightness (14.8 mag/sq.arcmin).  Extreme curve stretching has led to a noisy image.

The faintest stars visible here that also appear in the USNO A2.0 catalog are mag 19.  However, photometry using Iris, with reference to the GSC (Guide Star Catalog), indicate stars as faint as 20.5.  This is a million times fainter than the faintest star visible with the naked eye at my site (mag 5)!


Copyright 2003 to 2014, by TG Tan.  All rights reserved.  Copyright exists in all original material available on this website.  This material is for your personal individual, nonprofit use only.  Redistribution and/or public reproduction of this material is strictly prohibited without prior express written permission from the author.