Arp26
Galaxy in Ursa Major
About
The Pinwheel Galaxy, a face-on spiral about 21 million light-years away in Ursa Major, also catalogued as M101. Halton Arp listed it among spiral galaxies with one heavy arm. Six supernovae have been seen in it, including SN 2011fe and SN 2023ixf.
Imaging tips
- Spans about 29′, so 840–1,390 mm on APS-C frames it well; a short focal length leaves it small.
- Surface brightness is faint, about 23.8 mag/arcsec², so the outer arms need long total integration under dark skies.
- Broadband suits the galaxy itself; Hα pulled from a dual-band filter has been used to add red star-forming regions in the arms.
- Best placed around April and May, and it climbs near the zenith from mid-northern latitudes.
Facts
- Size
- 24′ × 23′
- Magnitude
- 7.9
- Coordinates
- RA 14h 3.2m, Dec +54° 21′
- Framing, APS-C
- 1010–1680 mm
- Framing, full frame
- 1550–2580 mm
- Best months
- Apr, May
- Peak altitude
- 86° from 50°N, 71° from 35°N