Arp220
Galaxy in Serpens
About
Arp 220, also catalogued as IC 4553 and IC 1127, is a pair of galaxies in Serpens that are colliding and merging. It lies about 250 million light-years away, nearer than any other ultraluminous infrared galaxy, and Hubble found over 200 massive star clusters in its centre. Arp filed it under "Galaxies with adjacent loops".
Imaging tips
- Wikipedia gives its size as only 1.5 × 1.2′, so it is too small to frame: use a long focal length and a fine pixel scale.
- Faint at 22.6 mag/arcsec², so plan many hours of broadband data.
- One imager's 2009 log records it with 9 × 45 s exposures and 5 × 60 s for the wide view, clear filter, 3 × 3 binning, on a 12-inch f/5.7 scope with a CCD camera.
- Best in May, when it reaches about 64° from 50°N.
Facts
- Size
- 2′ × 1′
- Magnitude
- 13.2
- Coordinates
- RA 15h 35.0m, Dec +23° 30′
- Framing, APS-C
- longer than 4000 mm
- Framing, full frame
- longer than 4000 mm
- Best months
- May
- Peak altitude
- 64° from 50°N, 79° from 35°N