M40 — Winnecke 4
Other in Ursa Major
About
Winnecke 4, not a nebula or cluster but a double star in Ursa Major. The stars are unrelated: one is about 1,000 light-years away and the other about 470. Messier probably logged it while checking a nebula Hevelius had reported in the area.
Imaging tips
- Listed at about 1′ and reported as 1.7′ by an imaging page, so it is too small to frame: use a long focal length and fine pixel scale.
- One imager used 1,085 mm and 57 minutes of 3-minute RGB subs from a Bortle 8 city backyard and called it a quick shot; the pair is bright enough for that.
- The same frame caught several faint background galaxies, such as NGC 4290 and NGC 4362, so a long focal length adds more than the double star.
- Best in March and April.
Facts
- Size
- 1′
- Magnitude
- 8.4
- Coordinates
- RA 12h 22.2m, Dec +58° 5′
- Framing, APS-C
- longer than 4000 mm
- Framing, full frame
- longer than 4000 mm
- Best months
- Mar, Apr
- Peak altitude
- 82° from 50°N, 67° from 35°N