When to photograph M 99 (Coma Pinwheel)
M 99, the Coma Pinwheel, is a galaxy in Coma Berenices, 5′ x 5′ across at magnitude 9.8. Also listed as NGC 4254.
When to photograph it
From 45° N the best months are February to April, with up to 7.8 hours of astronomical darkness above 30° in March. It reaches 59° at its highest.
From 35° S the best months are March to May, with up to 4.8 hours of astronomical darkness above 30° in March. It reaches 41° at its highest.
Framing
Its long axis is 5′. It fills 35 to 80% of the short side of an APS-C sensor at about 3750 to 8580 mm, and of a full-frame sensor at about 5780 to 13200 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 99'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 99
M 99 is only 5.0′ across, so it stays small in any amateur telescope. The longest focal length gives it the most pixels.
- Celestron C8 OTA 2032 mm f/10: fills 19% of an APS-C frame's short side View at High Point Scientific
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