B84
Dark Nebula in Sagittarius
About
A small dark nebula in Sagittarius, listed in Edward Emerson Barnard's catalogue of dark nebulae. It spans about 8 by 6 arcminutes.
Imaging tips
- At 3030–5050 mm on APS-C it spans a third to half of the frame, so it needs a long focal length.
- One imager used 11 frames of 4 minutes each, at 1,025 mm, f/8 and ISO 800.
- Broadband suits a dark nebula, which shows only against the stars behind it, so a dark sky keeps the contrast.
- Best around June and July; it peaks near 20° altitude from 50°N.
Facts
- Size
- 8′ × 6′
- Magnitude
- —
- Coordinates
- RA 17h 46.5m, Dec −20° 11′
- Framing, APS-C
- 3030–5050 mm
- Framing, full frame
- longer than 4000 mm
- Best months
- Jun, Jul
- Peak altitude
- 20° from 50°N, 35° from 35°N