More than astrophotography, an astronomical exploration.
NGC 891 and Abell 347
David Cruz · Astromidnight
In Andromeda, NGC 891 is a spiral much like the Milky Way seen exactly edge-on, cut in half by its dust lane. Around it, far more distant galaxies fill the background sky.
| Catalogue | New General Catalogue · NGC 891 |
| Type | Edge-on spiral galaxy |
| Distance | ≈ 32 million light-years |
| Field | 39.7′ × 26.2′ |
| Scale | 0.41″ / pixel |
| Orientation | −3° · north up |
| RA (centre) | 02h 22m 35s |
| DEC (centre) | +42° 19′ 52″ |
| Constellation | Andromeda |
| Objects in field | NGC 891 · [TT2009] 25 · 4 background galaxies · 1 quasar |
Distance of NGC 891 from the tip of the red giant branch (9.73 Mpc, cited by Müller et al. 2019); NASA gives about 30 million light-years. Distance of [TT2009] 25 by the same method (Müller et al. 2019). Distances of the background galaxies calculated from redshift (NED), with H0 = 70 km/s/Mpc; that of LEDA 2194768 is photometric and therefore less reliable, and that of PGC 9101 varies between studies (z = 0.0435 to 0.053). For the quasar the light travel time is given (flat cosmology with H0 = 70 and Ωm = 0.3). ZOAG G140.57-17.14 has no published distance. The centre of the Abell 347 cluster (SIMBAD) lies about 25′ beyond the left edge of the image. No real width: the field mixes NGC 891 with much more distant background galaxies. Positions of all objects taken from SIMBAD and NED.
14 h 12 min of light
Each tick is a 240-second exposure. 213 in total, with the camera at −10 °C and gain 100. Calibrated with 30 darks, 30 flats and 30 bias. The Moon stayed below 40 % illumination throughout.
Carbon Newton 10' f/4
ZWO ASI2600MC Pro
Twinstar Friction Mount FG80
Askar M54 OAG · ZWO ASI120MM Mini
TS-Optics Maxfield .95X Coma Corrector
Adobe Photoshop · Pleiades Astrophoto PixInsight · Stefan Berg Nighttime Imaging 'N' Astronomy (N.I.N.A. / NINA)
São Pedro da Gafanhoeira, Évora · 358 m
Bortle 3