How Many Subs

M98

NGC 4192 · Galaxy in Coma Berenices

Magnitude
10.1
Size
9.5′ × 3.2′
Effective surface brightness
22.4 mag/arcsec²
Best months
Mar, Apr, May
Declination
+15°
Filter
None (broadband target)

A nearly edge-on spiral in Coma, faint and elongated. Needs a dark sky or a long stack.

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 M98, 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 subs22%1 h 25 min513 subs2 h 22 min854 subs6 h 31 min2,346 subs
ZWO Seestar S50 Pro10 s subs11%1 h 35 min572 subs2 h 37 min941 subs7 h 06 min2,554 subs
ZWO Seestar S3010 s subs13%1 h 37 min584 subs2 h 34 min925 subs6 h 43 min2,416 subs
ZWO Seestar S30 Pro10 s subs7%1 h 42 min614 subs2 h 47 min1,002 subs7 h 30 min2,699 subs
DwarfLab DWARF 315 s subs10%1 h 51 min443 subs3 h 18 min794 subs9 h 42 min2,330 subs
DwarfLab DWARF mini15 s subs13%1 h 24 min338 subs2 h 21 min566 subs6 h 30 min1,560 subs
DwarfLab Draco30 s subs13%1 h 08 min137 subs1 h 56 min232 subs5 h 23 min646 subs
DwarfLab DWARF II15 s subs9%6 h 27 min1,549 subs9 h 05 min2,180 subs21 h4,942 subs
Vaonis Vespera II10 s subs11%1 h 25 min513 subs2 h 22 min854 subs6 h 31 min2,346 subs
Vaonis Vespera Pro10 s subs10%3 h 31 min1,269 subs5 h 31 min1,986 subs14 h5,121 subs
Vaonis Vespera 310 s subs11%1 h 21 min486 subs2 h 15 min813 subs6 h 14 min2,245 subs
Vaonis Vespera Pro 210 s subs10%3 h 19 min1,196 subs5 h 14 min1,885 subs14 h4,896 subs
Unistellar eQuinox 24 s subs28%1 h 59 min1,789 subs2 h 35 min2,321 subs5 h 10 min4,644 subs
Unistellar Odyssey4 s subs28%11 h9,628 subs13 h11,563 subs22 h20,016 subs
Celestron Origin10 s subs19%20 min119 subs36 min216 subs1 h 46 min639 subs
Celestron Origin Mark II10 s subs21%24 min147 subs48 min286 subs2 h 29 min895 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