M73 — Y-Asterism
Other in Aquarius
About
NGC 6994, an asterism of four stars in Aquarius, once taken for a small open cluster. Gaia places the stars between about 1,030 and 2,290 light-years away, so they are only a chance alignment. Messier himself noted some nebulosity, which Herschel could not confirm.
Imaging tips
- Only about 3′ across, so too small to frame: use a long focal length and a fine pixel scale.
- M72, a globular cluster, lies about 1.5° west, so the two share a frame only with a wide lens or a mosaic.
- One imager shot 10 hours of 300 s subs with M72 and found the asterism easy but plain, with simple processing: stretch, noise reduction and colour.
- The same long run was aimed at faint dust in the field, which only showed after stacking.
- Best around July and August; it stays below 28° altitude from 50°N.
Facts
- Size
- 3′
- Magnitude
- 9.0
- Coordinates
- RA 20h 59.0m, Dec −12° 38′
- Framing, APS-C
- longer than 4000 mm
- Framing, full frame
- longer than 4000 mm
- Best months
- Jul, Aug
- Peak altitude
- 27° from 50°N, 42° from 35°N