C57
Galaxy in Sagittarius
About
NGC 6822 is a small irregular galaxy in Sagittarius; its light takes about 1.6 million years to reach us. It ranks among the closest galaxies to our own that are not satellites of it. E. E. Barnard found it in 1884, and Edwin Hubble later used its variable stars to show it lies far outside the Milky Way.
Imaging tips
- Faint for its size at 24.9 mag/arcsec², so plan many hours of broadband data. A 6-hour LRGB set from La Palma and an 8-hour one both show the galaxy and its star-forming knots.
- Spans roughly 15′, which suits 1390–2320 mm on APS-C (2130–3560 mm full frame).
- Dusty Milky Way foreground reddens the galaxy (E(B−V) about 0.24 mag), so expect to adjust colour balance.
- Hα adds its bright star-forming regions: one 25-hour project gave Hα 76 subs of 10 minutes on top of LRGB.
- Best around July; it peaks near 25° altitude from 50°N.
Facts
- Size
- 17.4′ × 16.8′
- Magnitude
- 10.1
- Coordinates
- RA 19h 44.9m, Dec −14° 48′
- Framing, APS-C
- 1390–2320 mm
- Framing, full frame
- 2130–3560 mm
- Best months
- Jul
- Peak altitude
- 25° from 50°N, 40° from 35°N