Andromeda Galaxy

M31, NGC 224 · Galaxy in Andromeda

Magnitude: 3.4
Size: 178′ × 63′
Effective surface brightness: 22.2 mag/arcsec²
Best months: Sep, Oct, Nov
Declination: +41°
Filter: None (broadband target)

The nearest big spiral and the most imaged galaxy in the sky. The core arrives in minutes, the dust lanes in an hour, the faint outer disc needs a whole night. Too big for most smart-scope fields without mosaic.

Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.

How long with each smart telescope

Total integration for a solid image of the Andromeda Galaxy, default sub length, recommended filter. Click a cell for the full Bortle 1 to 9 table.
Telescope	Bortle 3 (rural)	Bortle 5 (suburban)	Bortle 7 (urban edge)
ZWO Seestar S5010 s subs	46 min279 subs	1 h 08 min408 subs	2 h 41 min969 subs
ZWO Seestar S50 Pro10 s subs	38 min227 subs	1 h 01 min366 subs	2 h 42 min973 subs
ZWO Seestar S3010 s subs	34 min204 subs	55 min332 subs	2 h 29 min893 subs
ZWO Seestar S30 Pro10 s subs	40 min243 subs	1 h 05 min389 subs	2 h 51 min1,028 subs
DwarfLab Dwarf 315 s subs	55 min219 subs	1 h 28 min351 subs	3 h 52 min929 subs
DwarfLab Dwarf Mini15 s subs	31 min123 subs	52 min208 subs	2 h 25 min582 subs
DwarfLab Dwarf II15 s subs	2 h 31 min603 subs	3 h 30 min840 subs	7 h 50 min1,879 subs
Vaonis Vespera II10 s subs	34 min204 subs	55 min332 subs	2 h 29 min893 subs
Vaonis Vespera Pro10 s subs	1 h 39 min596 subs	2 h 24 min866 subs	5 h 41 min2,045 subs
Unistellar eQuinox 24 s subs	46 min690 subs	59 min890 subs	1 h 58 min1,764 subs
Unistellar Odyssey4 s subs	4 h 05 min3,683 subs	4 h 54 min4,410 subs	8 h 26 min7,591 subs
Celestron Origin10 s subs	8 min48 subs	14 min85 subs	41 min244 subs

Open in the calculator

Imaging the galaxy

Galaxies are broadband targets: their light is mostly starlight spread across the spectrum, so a dual-band filter throws most of it away and makes things slower, not faster. Shoot without a filter (or with a plain UV/IR cut) and rely on total time and a dark sky. The core of a galaxy is usually many times brighter than its outer disc, so a short stack shows the nucleus long before the arms; the figures here are for the arms and disc, not the core.

Field rotation in Alt-Az mode crops the edges of the stack over a long session, so on a big galaxy re-centre now and then or use EQ mode where your scope supports it.

Andromeda Galaxy

How long with each smart telescope

Imaging the galaxy

Per-telescope pages