Arp78
Galaxy in Aries
About
In Aries, 106 million light-years off, this big unbarred spiral spans near 200,000 light-years, a little more than the Milky Way. Arp listed it for its compact, bright companion NGC 770, a dwarf elliptical whose tidal pull likely drew out one oversized arm.
Imaging tips
- Faint at 22.8 mag/arcsec², so plan many hours of broadband data; one imager gathered 22 h 10 min of 300 s subs, mostly luminance, with a 152 mm refractor.
- Apparent size is about 7′ × 4′. At 3460–5770 mm on APS-C it fills a third to half of the frame, so it calls for a long focal length.
- Its companion NGC 770 is a dwarf elliptical, and its tidal pull likely shaped the single long outer arm; dust lanes and blue young clusters line that arm.
- Best around October and November; it peaks near 59° altitude from 50°N.
Facts
- Size
- 5′ × 3′
- Magnitude
- 10.3
- Coordinates
- RA 1h 59.3m, Dec +19° 0′
- Framing, APS-C
- longer than 4000 mm
- Framing, full frame
- longer than 4000 mm
- Best months
- Oct, Nov
- Peak altitude
- 59° from 50°N, 74° from 35°N