When to photograph M 71
M 71 is a globular cluster in Sagitta, 7′ across at magnitude 6.1. Also listed as NGC 6838.
When to photograph it
From 45° N the best months are August and September, with up to 5.7 hours of astronomical darkness above 30° in August. It reaches 64° at its highest.
From 35° S the best months are June to August, with up to 3.7 hours of astronomical darkness above 30° in June. It reaches 36° at its highest.
Framing
Its long axis is 7′. It fills 35 to 80% of the short side of an APS-C sensor at about 2720 to 6220 mm, and of a full-frame sensor at about 4190 to 9570 mm.
Filters and the moon
Clusters are broadband targets, but bright ones tolerate some moonlight and light pollution. Short subs keep the brightest stars from clipping. The dark sky calendar shows which nights this month are moon-free where you are.
Plan it for tonight
Dates and times depend on your exact location. The imaging planner shows M 71's altitude through tonight, its transit time and its distance from the moon. For sub length, use the exposure calculator.
Nearby targets
Gear that suits M 71
M 71 is 6.9′ along its long axis. These frame it on an APS-C sensor with room to crop.
- Celestron C8 OTA 2032 mm f/10: fills 26% of an APS-C frame's short side View at High Point Scientific
- Celestron EdgeHD 8 OTA 2032 mm f/10: fills 26% of an APS-C frame's short side View at High Point Scientific
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