When to photograph M 109
M 109 is a galaxy in Ursa Major, 8′ x 6′ across at magnitude 9.9. Also listed as NGC 3992.
When to photograph it
From 45° N the best months are January to March, with up to 9.7 hours of astronomical darkness above 30° in February. It reaches 82° 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 2° 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 8′. It fills 35 to 80% of the short side of an APS-C sensor at about 2320 to 5300 mm, and of a full-frame sensor at about 3570 to 8150 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 109's altitude through tonight, its transit time and its distance from the moon. For sub length, use the exposure calculator.
Nearby targets
- NGC 4088 3.1° away
- M 40 Winnecke 4 5.8° away
- M 97 Owl Nebula 6.5° away
- M 106 7.0° away
- M 108 7.1° away
- NGC 4449 10.5° away
Gear that suits M 109
M 109 is 8.1′ along its long axis. These frame it on an APS-C sensor with room to crop.
- Celestron C8 OTA 2032 mm f/10: fills 31% of an APS-C frame's short side View at High Point Scientific
- Celestron EdgeHD 8 OTA 2032 mm f/10: fills 31% of an APS-C frame's short side View at High Point Scientific
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