When to photograph M 101 (Pinwheel Galaxy)
M 101, the Pinwheel Galaxy, is a galaxy in Ursa Major, 24′ x 23′ across at magnitude 7.9. Also listed as NGC 5457.
When to photograph it
From 45° N the best months are February to April, with up to 8.7 hours of astronomical darkness above 30° in March. It reaches 81° at its highest. It never sets from this latitude, so some imaging is possible all year.
From 35° S it never climbs above 30°. It peaks at 1° 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 24′. It fills 35 to 80% of the short side of an APS-C sensor at about 780 to 1790 mm, and of a full-frame sensor at about 1200 to 2750 mm.
Filters and the moon
Galaxies are broadband targets. Filters cannot separate their light from light pollution, so dark skies and moon-free nights matter most. 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 101's altitude through tonight, its transit time and its distance from the moon. For sub length, use the exposure calculator.
Nearby targets
- M 51 Whirlpool Galaxy 8.9° away
- M 102 Spindle Galaxy 9.2° away
- NGC 5907 Splinter Galaxy 10.5° away
- M 40 Winnecke 4 14.4° away
- M 63 Sunflower Galaxy 14.6° away
- M 106 17.8° away
Gear that suits M 101
M 101 is 24′ along its long axis. These frame it on an APS-C sensor with room to crop.
- Sky-Watcher Esprit 120ED 840 mm f/7: fills 38% of an APS-C frame's short side View at High Point Scientific
- Sky-Watcher Quattro 200P 800 mm f/4: fills 36% of an APS-C frame's short side View at High Point Scientific
- Sky-Watcher 130PDS 650 mm f/5: fills 29% of an APS-C frame's short side View at High Point Scientific
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