Arp 29: The fireworks galaxy

North is right. 0.55"/pixel (26'x26' field). FWHM=3.7" This one is in the Atlas of Pecular Galaxies under "one heavy arm", which checks out: the eastern arm (down) is considerably bighter and denser than the others. However, it's mostly known for it's bright star formation, and being close enough and it's close enough to resolve multiple HII regions and a bright star cluster: It's also had ten observed supernova, hence "fireworks galaxy". In the sky, it apears very close to the milky way, which can be seen as the unusally dense star field. Also, there's a lot of dust blocking the galaxy's light which results in it's low surface brightness. It also makes luminosity measurements unreliable, and because it's too close for acurate redshift data (z=0.00015), it's hard to tell how far away it is: I'd guess somewhere between 10 and 30 million light years. Total exposure time:504 * 30 seconds = 4.2 hours. Used in stack:417 * 30 seconds = 3.4 hours. Telescope: C9.25 (230mm, f/10, fl=2300mm) +…