When to photograph M 13 (Hercules Cluster)
M 13, the Hercules Cluster, is a globular cluster in Hercules, 17′ across at magnitude 5.8. Also listed as NGC 6205.
When to photograph it
From 45° N the best months are March to May, with up to 5.8 hours of astronomical darkness above 30° in April. It reaches 81° at its highest.
From 35° S it never climbs above 30°. It peaks at 19° when it crosses the meridian, low enough that haze and light pollution soften it. It is possible with a clear northern horizon, but hard.
Framing
Its long axis is 17′. It fills 35 to 80% of the short side of an APS-C sensor at about 1140 to 2600 mm, and of a full-frame sensor at about 1750 to 4000 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 13's altitude through tonight, its transit time and its distance from the moon. For sub length, use the exposure calculator.
Nearby targets
- M 92 9.5° away
- NGC 5907 Splinter Galaxy 24.6° away
- M 102 Spindle Galaxy 25.1° away
- M 57 Ring Nebula 27.2° away
- NGC 6543 Cat's Eye Nebula 32.1° away
- M 101 Pinwheel Galaxy 32.4° away
Gear that suits M 13
M 13 is 17′ along its long axis. These frame it on an APS-C sensor with room to crop.
- Celestron C8 OTA 2032 mm f/10: fills 63% of an APS-C frame's short side View at High Point Scientific
- Celestron EdgeHD 8 OTA 2032 mm f/10: fills 63% of an APS-C frame's short side View at High Point Scientific
- Sky-Watcher Esprit 120ED 840 mm f/7: fills 26% of an APS-C frame's short side View at High Point Scientific
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