When to photograph NGC 4631 (Whale Galaxy)
NGC 4631, the Whale Galaxy, is a galaxy in Canes Venatici, 15′ x 2′ across at magnitude 9.2. Also listed as C 32.
When to photograph it
From 45° N the best months are February to April, with up to 8.5 hours of astronomical darkness above 30° in March. It reaches 78° at its highest.
From 35° S it never climbs above 30°. It peaks at 22° 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 15′. It fills 35 to 80% of the short side of an APS-C sensor at about 1290 to 2960 mm, and of a full-frame sensor at about 1990 to 4550 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 NGC 4631's altitude through tonight, its transit time and its distance from the moon. For sub length, use the exposure calculator.
Nearby targets
- NGC 4656 Hockey Stick Galaxy 0.5° away
- NGC 4559 4.8° away
- NGC 4889 6.0° away
- NGC 4565 Needle Galaxy 6.7° away
- NGC 4725 7.3° away
- NGC 4244 7.3° away
Gear that suits NGC 4631
NGC 4631 is 15′ along its long axis. These frame it on an APS-C sensor with room to crop.
- Celestron C8 OTA 2032 mm f/10: fills 55% of an APS-C frame's short side View at High Point Scientific
- Celestron EdgeHD 8 OTA 2032 mm f/10: fills 55% of an APS-C frame's short side View at High Point Scientific
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