Arp214
Galaxy in Ursa Major
About
NGC 3718, a barred spiral in Ursa Major crossed by a heavy dust lane, whose innermost gas disc orbits across the galaxy's poles; that arrangement defines a polar ring. Sources put it at roughly 48 to 70 million light-years. Arp placed it under "Galaxies with irregularities, absorption, and resolution".
Imaging tips
- One source gives 8.1 × 3.9′, a small target: use a long focal length and a fine pixel scale.
- NGC 3729 lies about 11′ east, and the compact group Hickson 56, five tiny galaxies, sits about 8′ south, so both are nearby but a wider field than the galaxy itself.
- Faint at 22.8 mag/arcsec², so plan many hours of broadband data. One imager gathered 18.8 hours: 53 luminance frames of 900 s and 22 each of red, green and blue at 300 s.
- The central dust lane is clearly captured in one imager's 12 × 6 minute colour stack from a 25 cm scope at 1600 mm focal length.
- Best around February to April, when it passes almost overhead (about 87°) from 50°N.
Facts
- Size
- 6′ × 3′
- Magnitude
- 11.0
- Coordinates
- RA 11h 32.6m, Dec +53° 4′
- Framing, APS-C
- longer than 4000 mm
- Framing, full frame
- longer than 4000 mm
- Best months
- Feb, Mar, Apr
- Peak altitude
- 87° from 50°N, 72° from 35°N