C17
Galaxy in Cassiopeia
About
NGC 147, a dwarf spheroidal galaxy in Cassiopeia about 2.5 million light-years away and a satellite of the Andromeda Galaxy. John Herschel found it in 1829, and Walter Baade resolved it into individual stars in 1944.
Imaging tips
- About 13′ × 8′ on the sky (Wikipedia) and faint at 22.6 mag/arcsec², so plan many hours of broadband data.
- One LRGB image used about 11.8 hours (480 min luminance) under Bortle 6 skies; the author notes it is fainter than neighbouring NGC 185.
- NGC 185 (Caldwell 18) lies about 1° away, so both fit only in a wider field.
- Best in September and October; it peaks near 88° from 50°N.
Facts
- Size
- 9.4′ × 5.4′
- Magnitude
- 9.7
- Coordinates
- RA 0h 33.2m, Dec +48° 31′
- Framing, APS-C
- 2580–4300 mm
- Framing, full frame
- 3950–6580 mm
- Best months
- Sep, Oct
- Peak altitude
- 89° from 50°N, 77° from 35°N