M65

NGC 3623 · Galaxy in Leo

Magnitude: 9.3
Size: 10′ × 3′
Effective surface brightness: 21.6 mag/arcsec²
Best months: Feb, Mar, Apr
Declination: +13°
Filter: None (broadband target)

One of the Leo Triplet, an inclined spiral with a bright core. Fits in a frame with M66 and NGC 3628.

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 M65, default sub length, recommended filter, and how much of each frame it fills. Click a cell for the full Bortle 1 to 9 table.
Telescope	In frame	Bortle 3 (rural)	Bortle 5 (suburban)	Bortle 7 (urban edge)
ZWO Seestar S5010 s subs	23%	22 min132 subs	34 min204 subs	1 h 27 min520 subs
ZWO Seestar S50 Pro10 s subs	12%	24 min146 subs	37 min224 subs	1 h 34 min566 subs
ZWO Seestar S3010 s subs	14%	24 min147 subs	36 min219 subs	1 h 29 min535 subs
ZWO Seestar S30 Pro10 s subs	7%	26 min156 subs	40 min238 subs	1 h 40 min598 subs
DwarfLab DWARF 315 s subs	10%	29 min118 subs	48 min192 subs	2 h 09 min517 subs
DwarfLab DWARF mini15 s subs	14%	22 min87 subs	34 min135 subs	1 h 26 min346 subs
DwarfLab Draco30 s subs	13%	18 min36 subs	28 min56 subs	1 h 12 min144 subs
DwarfLab DWARF II15 s subs	9%	1 h 32 min370 subs	2 h 06 min504 subs	4 h 32 min1,090 subs
Vaonis Vespera II10 s subs	12%	22 min132 subs	34 min204 subs	1 h 27 min520 subs
Vaonis Vespera Pro10 s subs	10%	53 min317 subs	1 h 18 min469 subs	3 h 09 min1,133 subs
Vaonis Vespera 310 s subs	11%	21 min125 subs	32 min194 subs	1 h 23 min498 subs
Vaonis Vespera Pro 210 s subs	10%	50 min299 subs	1 h 14 min445 subs	3 h 01 min1,084 subs
Unistellar eQuinox 24 s subs	29%	28 min415 subs	35 min527 subs	1 h 08 min1,020 subs
Unistellar Odyssey4 s subs	30%	2 h 25 min2,169 subs	2 h 52 min2,579 subs	4 h 51 min4,371 subs
Celestron Origin10 s subs	20%	5 min32 subs	9 min53 subs	24 min142 subs
Celestron Origin Mark II10 s subs	22%	7 min41 subs	12 min70 subs	33 min199 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.

M65

How long with each smart telescope

Imaging the galaxy

Per-telescope pages