How Many Subs

M61

NGC 4303 · Galaxy in Virgo

Magnitude
9.7
Size
6′ × 5.5′
Effective surface brightness
22.1 mag/arcsec²
Best months
Mar, Apr, May
Declination
+4°
Filter
None (broadband target)

A face-on barred spiral at the southern end of the Virgo cluster, with well-defined arms.

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 M61, 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 subs14%1 h 13 min438 subs1 h 59 min712 subs5 h 18 min1,911 subs
ZWO Seestar S50 Pro10 s subs7%1 h 21 min487 subs2 h 11 min784 subs5 h 47 min2,080 subs
ZWO Seestar S3010 s subs8%1 h 22 min495 subs2 h 08 min769 subs5 h 28 min1,967 subs
ZWO Seestar S30 Pro10 s subs4%1 h 27 min522 subs2 h 19 min834 subs6 h 06 min2,198 subs
DwarfLab DWARF 315 s subs6%1 h 35 min382 subs2 h 46 min665 subs7 h 55 min1,899 subs
DwarfLab DWARF mini15 s subs8%1 h 12 min289 subs1 h 58 min472 subs5 h 17 min1,270 subs
DwarfLab Draco30 s subs8%58 min117 subs1 h 36 min193 subs4 h 23 min526 subs
DwarfLab DWARF II15 s subs6%5 h 23 min1,292 subs7 h 30 min1,800 subs17 h4,019 subs
Vaonis Vespera II10 s subs7%1 h 13 min438 subs1 h 59 min712 subs5 h 18 min1,911 subs
Vaonis Vespera Pro10 s subs6%2 h 59 min1,073 subs4 h 35 min1,650 subs12 h4,169 subs
Vaonis Vespera 310 s subs7%1 h 09 min415 subs1 h 53 min678 subs5 h 05 min1,829 subs
Vaonis Vespera Pro 210 s subs6%2 h 49 min1,013 subs4 h 21 min1,566 subs11 h3,986 subs
Unistellar eQuinox 24 s subs18%1 h 38 min1,477 subs2 h 07 min1,905 subs4 h 11 min3,772 subs
Unistellar Odyssey4 s subs18%8 h 45 min7,882 subs10 h9,437 subs18 h16,231 subs
Celestron Origin10 s subs12%17 min103 subs30 min181 subs1 h 27 min521 subs
Celestron Origin Mark II10 s subs13%21 min128 subs40 min240 subs2 h 02 min730 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