M105

NGC 3379 · Galaxy in Leo

Magnitude: 9.3
Size: 5.4′ × 4.8′
Effective surface brightness: 21.5 mag/arcsec²
Best months: Feb, Mar, Apr
Declination: +13°
Filter: None (broadband target)

An elliptical in the Leo I group, with NGC 3384 and NGC 3389 forming a tight trio.

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 M105, 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	13%	26 min155 subs	39 min236 subs	1 h 38 min590 subs
ZWO Seestar S50 Pro10 s subs	7%	29 min172 subs	43 min259 subs	1 h 47 min642 subs
ZWO Seestar S3010 s subs	8%	29 min172 subs	42 min253 subs	1 h 41 min607 subs
ZWO Seestar S30 Pro10 s subs	4%	30 min183 subs	46 min276 subs	1 h 53 min678 subs
DwarfLab DWARF 315 s subs	5%	35 min139 subs	56 min223 subs	2 h 27 min587 subs
DwarfLab DWARF mini15 s subs	8%	25 min102 subs	39 min156 subs	1 h 38 min392 subs
DwarfLab Draco30 s subs	7%	21 min42 subs	32 min65 subs	1 h 21 min163 subs
DwarfLab DWARF II15 s subs	5%	1 h 47 min429 subs	2 h 25 min579 subs	5 h 08 min1,234 subs
Vaonis Vespera II10 s subs	6%	26 min155 subs	39 min236 subs	1 h 38 min590 subs
Vaonis Vespera Pro10 s subs	6%	1 h 02 min370 subs	1 h 30 min541 subs	3 h 34 min1,285 subs
Vaonis Vespera 310 s subs	6%	24 min147 subs	37 min225 subs	1 h 34 min565 subs
Vaonis Vespera Pro 210 s subs	5%	58 min350 subs	1 h 26 min514 subs	3 h 25 min1,229 subs
Unistellar eQuinox 24 s subs	16%	32 min476 subs	40 min602 subs	1 h 17 min1,154 subs
Unistellar Odyssey4 s subs	16%	2 h 45 min2,471 subs	3 h 15 min2,930 subs	5 h 29 min4,937 subs
Celestron Origin10 s subs	11%	6 min38 subs	10 min61 subs	27 min161 subs
Celestron Origin Mark II10 s subs	12%	8 min49 subs	14 min82 subs	38 min226 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.

M105

How long with each smart telescope

Imaging the galaxy

Per-telescope pages