B86 — Ink Spot
Dark Nebula in Sagittarius
About
The Ink Spot is a small dark nebula in Sagittarius, a cold, dense Bok globule whose dust hides the Milky Way behind it. It measures about 4′, or 6 to 7 light-years across. Stars that appear inside it are foreground. Open cluster NGC 6520, next to it, lies about 6,000 light-years away, and the nebula seems to be farther.
Imaging tips
- Only about 4–5′ across, so it is too small to frame: use a long focal length and a fine pixel scale.
- NGC 6520 (an open cluster, 5′ across, magnitude 7.6) lies just east of it. One imager framed both at 1,025 mm with a 33.77′ × 22.53′ field.
- Dark nebulae need broadband. One imager's HaRGB frame came to 22 h 54 min in total; another took 13 × 240 s with a modified DSLR and no filter (52 minutes).
- Best around June and July, but it peaks near 12° altitude from 50°N and near 27° from 35°N.
Facts
- Size
- 5′ × 4′
- Magnitude
- —
- Coordinates
- RA 18h 2.9m, Dec −27° 52′
- Framing, APS-C
- longer than 4000 mm
- Framing, full frame
- longer than 4000 mm
- Best months
- Jun, Jul
- Peak altitude
- 12° from 50°N, 27° from 35°N