M5
Globular Cluster in Serpens
About
A globular cluster in Serpens, about 24,500 light-years away and roughly 10.6 billion years old. It has 105 known variable stars and is moving away from us at more than 50 km/s.
Imaging tips
- At 1,210–2,020 mm on APS-C (1,860–3,090 mm on full frame) the cluster spans a third to half of the frame, at about 20′ across.
- The bright star 5 Serpentis is nearby, about 22′ away, so expect it at the edge of the field.
- The core is the dynamic-range problem: one imager stacked ten 5-minute subs for the outer stars and 2-minute subs for the core, then blended them with layer masks.
- Guide well: one team drops any frame with even small star trails, since they blur the cluster. One hour of 1-minute subs was enough for a clean result.
- Best in April and May; it stays below 42° altitude from 50°N.
Facts
- Size
- 20′
- Magnitude
- 5.6
- Coordinates
- RA 15h 18.6m, Dec +2° 5′
- Framing, APS-C
- 1210–2020 mm
- Framing, full frame
- 1860–3090 mm
- Best months
- Apr, May
- Peak altitude
- 42° from 50°N, 57° from 35°N