Steve Crouch has come up with this pearler of a galaxy group, with NGC 7172 showing beautiful dust lanes and colour. Look closely and you’ll see at least 40 galaxies in this single photo! With an average of 100 billion stars per galaxy, that’s a heck of a lot of stars…
Catalogue and alternative designations NGC 7172 galaxy group, Hickson 90
Type Compact galaxy group
Position 22 02.0, -31 52
Constellation Piscis Austrinus Camera and Telescope STXL11002 and 36.8 cm Ritchey Chretien Focal Ratio F9
Exposure Details LRGB 225:45:40:40 Luminance binned 1×1, Colours 2×2 with Baader filters
This little group of galaxies doesn’t seem to be imaged much. NGC 7172 is lower left of centre (with the dust lane). NGC 7173, 7174 and 7176 form the interacting group just above centre. ESO 466-46 and 466-47 are to the lower right. The bright star is magnitude 6.7.
Galaxies range in size from 10 million stars up to 100 trillion! And there are some 170 billion galaxies in the known observable universe… Incomprehensible numbers.
I’ve had this data for M94 hanging around a while and wasn’t going to process it because I thought it was pretty poor quality. Anyway I employed the usual astrophotographic data manipulation techniques and came up with something that didn’t look too bad although it would have benefited from a lot more data. Of course you have to remember that this is only a small telescope.
This could be one of the last images from the Arizona telescope as my access is very infrequent now. I can’t complain though because I’ve had a good run.