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. Click a cell for the full Bortle 1 to 9 table.
TelescopeBortle 3 (rural)Bortle 5 (suburban)Bortle 7 (urban edge)
ZWO Seestar S5010 s subs, dual-band3 h 19 min1,197 subs3 h 41 min1,326 subs5 h 15 min1,892 subs
ZWO Seestar S50 Pro10 s subs, dual-band2 h 12 min791 subs2 h 35 min931 subs4 h 17 min1,543 subs
ZWO Seestar S3010 s subs, dual-band1 h 55 min692 subs2 h 17 min821 subs3 h 51 min1,387 subs
ZWO Seestar S30 Pro10 s subs, dual-band2 h 24 min863 subs2 h 48 min1,010 subs4 h 36 min1,654 subs
DwarfLab Dwarf 315 s subs, dual-band3 h 12 min770 subs3 h 46 min903 subs6 h 11 min1,486 subs
DwarfLab Dwarf Mini15 s subs, dual-band1 h 33 min372 subs1 h 54 min458 subs3 h 29 min835 subs
DwarfLab Dwarf II15 s subs7 h 44 min1,856 subs11 h2,639 subs25 h6,061 subs
Vaonis Vespera II10 s subs1 h 40 min602 subs2 h 51 min1,025 subs7 h 59 min2,873 subs
Vaonis Vespera Pro10 s subs5 h 03 min1,816 subs7 h 31 min2,705 subs18 h6,590 subs
Unistellar eQuinox 24 s subs2 h 24 min2,164 subs3 h 08 min2,823 subs6 h 20 min5,702 subs
Unistellar Odyssey4 s subs13 h11,739 subs16 h14,136 subs27 h24,611 subs
Celestron Origin10 s subs23 min138 subs43 min258 subs2 h 10 min782 subs

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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) 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