M31, the Andromeda Galaxy

1100mm/F7.3 telescope
Pentax 645z (astro-modified)
three-frame mosaic
total exposure time = 53.7 hr (45.7 hr of RGB + 7.9 hr of Hα)
original image is 31320 x 17220 (539 mega pixels)

see <a href="http://www.gigapan.com/embeds/xp5Hj6H2dlw/" rel="noreferrer nofollow">www.gigapan.com/embeds/xp5Hj6H2dlw/</a> for a pan/zoomable high-resolution version.

see <a href="https://astrob.in/369032/0/" rel="noreferrer nofollow">astrob.in/369032/0/</a> for more technical details.