The Tadpole galaxy:

North is up (exact, mirrored). 0.53 "/pixel [18.8' x 7.4'] FWHM = 4.2" This galaxy has a massive (and rather bright) tidal tail, but I can't see an obvious companion galaxy. The general consensus is that there's a second galaxy behind it... although a nearby elliptical has a suspiciously similar redshift: Total exposure time:364 * 30 seconds = 3 hours. Used in stack:165 * 30 seconds = 1.3 hours. Telescope: C9.25 (230mm, f/10, fl=2300mm) + 0.63 Starizona reducer Camera: IMX533 (16mm diagonal, square, color) Processing: Callibration (dark + flat) Stacking (average w/ outlier rejection) White balance and background subtraction (no gradient removal) Asinh stretch (color preserving) Rotation + crop Tone curve Not my finest work due to some patchy clouds, but not terrible. Related: /astro/arp188/stacked.fits.fz: Raw stacks https://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp188.jpeg: Arp's image