H-NGC129
Open Cluster in Cassiopeia
About
An open cluster in Cassiopeia, roughly 5,300 to 5,450 light-years away and about 77 million years old. Its brightest member, DL Cassiopeiae, is a Cepheid variable that cycles in 8 days, and that star has been used to estimate the cluster's distance.
Imaging tips
- Framing of 1150–1920 mm on APS-C suits the cluster. Sources give its size as 12–21′ and its membership as 35–193 stars, so where the cluster ends is loosely defined.
- A handful of members are magnitude 8 and 9, the rest mostly 10 and 11, with no nebulosity mentioned, so broadband colour is the natural choice.
- One imager collected about 2 hours of LRGB: 10 × 3 min luminance and 6 × 5 min in each colour channel.
- Best around September and October, when it peaks near 80° from 50°N.
Facts
- Size
- 21′
- Magnitude
- 6.5
- Coordinates
- RA 0h 30.4m, Dec +60° 13′
- Framing, APS-C
- 1150–1920 mm
- Framing, full frame
- 1770–2950 mm
- Best months
- Sep, Oct
- Peak altitude
- 80° from 50°N, 65° from 35°N