Arp147
Galaxy in Cetus
About
Two ring-shaped galaxies in Cetus, catalogued as IC 298, lying roughly 430 to 440 million light-years away. Arp listed it among galaxies with associated rings. Its bright blue ring comes from a wave of star formation that began about 40 million years ago.
Imaging tips
- Under 1′ across in the sources, so it is too small to frame: use a long focal length and a fine pixel scale.
- Faint at 22.6 mag/arcsec² and a galaxy, so plan broadband data; one imager used true-colour filters and noted the pair is too faint for the eye to see colour.
- One imager took 10 frames of 6 minutes with a 10-inch Schmidt-Cassegrain at 1600 mm and a sky-glow filter.
- A star beside the pair was far more prominent in one amateur image than in the Hubble view, so expect it in the frame.
- Best in October and November; it peaks near 41° altitude from 50°N.
Facts
- Size
- 1′ × 1′
- Magnitude
- 14.0
- Coordinates
- RA 3h 11.3m, Dec +1° 19′
- Framing, APS-C
- longer than 4000 mm
- Framing, full frame
- longer than 4000 mm
- Best months
- Oct, Nov
- Peak altitude
- 41° from 50°N, 56° from 35°N