One-color image of the disturbed galaxy Arp-Madore 135-650, also known as NGC 646. This was observed for one of the gap-filler programs. If I could make a color image, it might appear blueish up top where all the star formation is ongoing, and less blue at the bottom. This is what makes the galaxy interesting, according to a brief mention on Twitter by principle investigator Julianne Dalcanton: twitter.com/dalcantonJD/status/1038436462876741633
The puzzle is to figure out why is it all clumpy and star-formy on one side, but smooth and not so much on the other side.
I cleaned off a satellite trail and a few hundred cosmic rays.
Data from the following proposal is used to create this image:
All channels: ACS/WFC F606W
North is NOT up. It is 43.07° counter-clockwise from up.