How Many Subs

Heart Nebula

IC 1805, Sh2-190 · Emission nebula in Cassiopeia

Magnitude
6.5
Size
60′
Effective surface brightness
22.8 mag/arcsec²
Best months
Oct, Nov, Dec
Declination
+61°
Filter
Dual-band recommended

A degree-wide hydrogen cloud shaped like a heart, with the bright Melotte 15 cluster and pillars at its centre. Dual-band, and a wide field or mosaic.

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 Heart Nebula, 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 subs, dual-band1.4× frame1 h 55 min692 subs2 h 17 min821 subs3 h 51 min1,387 subs
ZWO Seestar S50 Pro10 s subs, dual-band72%2 h 12 min791 subs2 h 35 min931 subs4 h 17 min1,543 subs
ZWO Seestar S3010 s subs, dual-band84%2 h 25 min870 subs2 h 46 min999 subs4 h 21 min1,565 subs
ZWO Seestar S30 Pro10 s subs, dual-band45%2 h 24 min863 subs2 h 48 min1,010 subs4 h 36 min1,654 subs
DwarfLab DWARF 315 s subs, dual-band61%2 h 04 min496 subs2 h 37 min629 subs5 h 03 min1,211 subs
DwarfLab DWARF mini15 s subs, dual-band84%1 h 53 min451 subs2 h 14 min537 subs3 h 48 min914 subs
DwarfLab Draco30 s subs, dual-band80%1 h 29 min178 subs1 h 47 min214 subs3 h 05 min371 subs
DwarfLab DWARF II15 s subs56%7 h 44 min1,856 subs11 h2,639 subs25 h6,061 subs
Vaonis Vespera II10 s subs70%1 h 40 min602 subs2 h 51 min1,025 subs7 h 59 min2,873 subs
Vaonis Vespera Pro10 s subs62%4 h 10 min1,501 subs6 h 38 min2,390 subs17 h6,275 subs
Vaonis Vespera 310 s subs68%1 h 35 min569 subs2 h 42 min975 subs7 h 38 min2,750 subs
Vaonis Vespera Pro 210 s subs60%3 h 56 min1,414 subs6 h 18 min2,267 subs17 h5,998 subs
Unistellar eQuinox 24 s subs1.8× frame2 h 24 min2,164 subs3 h 08 min2,823 subs6 h 20 min5,702 subs
Unistellar Odyssey4 s subs1.8× frame13 h11,739 subs16 h14,136 subs27 h24,611 subs
Celestron Origin10 s subs1.2× frame23 min138 subs43 min258 subs2 h 10 min782 subs
Celestron Origin Mark II10 s subs1.3× frame28 min168 subs57 min340 subs3 h 02 min1,095 subs

Open in the calculator

Imaging the emission nebula

Emission nebulae glow in a few narrow lines, mostly hydrogen-alpha (deep red) and doubly ionised oxygen (teal). A dual-band filter passes those lines and blocks most skyglow, which is why it cuts the time needed from a suburban sky so dramatically. Use it. From a genuinely dark site the gain is smaller because there is less skyglow to block, and read noise becomes the limit, which is where longer subs (EQ mode, or Expert Mode on a Vespera) earn their keep.

Stars lose colour through a dual-band filter; a short broadband stack blended in fixes that if you care.

Per-telescope pages