How Many Subs

Triangulum Galaxy

M33, NGC 598 · Galaxy in Triangulum

Magnitude
5.7
Size
73′ × 45′
Effective surface brightness
22.5 mag/arcsec²
Best months
Sep, Oct, Nov
Declination
+31°
Filter
None (broadband target)

Big, face-on and low in surface brightness. Nearly as bright as M31 overall but spread thin, so it needs far more time. Its H II regions pop with a dual-band filter.

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 Triangulum Galaxy, default sub length, recommended filter, and how much of each frame it fills. Click a cell for the full Bortle 1 to 9 table.
TelescopeIn frameBortle 3 (rural)Bortle 5 (suburban)Bortle 7 (urban edge)
ZWO Seestar S5010 s subs1.7× frame1 h362 subs1 h 41 min605 subs4 h 38 min1,669 subs
ZWO Seestar S50 Pro10 s subs88%1 h 07 min404 subs1 h 51 min667 subs5 h 03 min1,817 subs
ZWO Seestar S3010 s subs1.0× frame1 h 09 min412 subs1 h 49 min656 subs4 h 46 min1,719 subs
ZWO Seestar S30 Pro10 s subs54%1 h 12 min433 subs1 h 58 min710 subs5 h 20 min1,920 subs
DwarfLab DWARF 315 s subs74%1 h 18 min312 subs2 h 20 min562 subs6 h 54 min1,657 subs
DwarfLab DWARF mini15 s subs1.0× frame1 h239 subs1 h 40 min401 subs4 h 37 min1,110 subs
DwarfLab Draco30 s subsOnly just48 min97 subs1 h 22 min164 subs3 h 50 min460 subs
DwarfLab DWARF II15 s subs68%4 h 34 min1,097 subs6 h 27 min1,548 subs15 h3,516 subs
Vaonis Vespera II10 s subs85%1 h362 subs1 h 41 min605 subs4 h 38 min1,669 subs
Vaonis Vespera Pro10 s subs75%2 h 29 min897 subs3 h 55 min1,408 subs10 h3,643 subs
Vaonis Vespera 310 s subs83%57 min343 subs1 h 36 min576 subs4 h 26 min1,597 subs
Vaonis Vespera Pro 210 s subs74%2 h 21 min845 subs3 h 43 min1,336 subs9 h 40 min3,483 subs
Unistellar eQuinox 24 s subs2.1× frame1 h 25 min1,270 subs1 h 50 min1,649 subs3 h 40 min3,305 subs
Unistellar Odyssey4 s subs2.2× frame7 h 36 min6,843 subs9 h 08 min8,222 subs16 h14,250 subs
Celestron Origin10 s subs1.4× frame14 min84 subs25 min153 subs1 h 16 min455 subs
Celestron Origin Mark II10 s subs1.6× frame17 min103 subs34 min202 subs1 h 46 min637 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.

Per-telescope pages