H-NGC1817
Open Cluster in Taurus
About
Roughly a billion years old and about 6,400 light-years away in Taurus, this open cluster holds no fewer than 169 stars that share a common motion. Delta Scuti pulsators make up 16 of its 26 known variable stars. It is in the Herschel 400 list.
Imaging tips
- Sources give about 20′ across: 1510–2520 mm on APS-C (2320–3870 mm full frame) frames it, leaving room around the stars.
- NGC 1807, a looser group of bright stars, is about 25′ away. One imager fitted both into an 88′-wide field, where NGC 1817 was the larger, richer cluster.
- Surface brightness is 22.3 mag/arcsec², faint for a cluster of magnitude 7.7. One imager took 11 × 4-minute luminance frames plus 8 × 2-minute colour frames.
- Best in November and December, peaking near 57° altitude from 50°N.
Facts
- Size
- 16′
- Magnitude
- 7.7
- Coordinates
- RA 5h 12.5m, Dec +16° 42′
- Framing, APS-C
- 1510–2520 mm
- Framing, full frame
- 2320–3870 mm
- Best months
- Nov, Dec
- Peak altitude
- 57° from 50°N, 72° from 35°N