How long to image the Heart Nebula with the ZWO Seestar S50
From a Bortle 6 suburban sky, the ZWO Seestar S50 needs about 2 h 49 min (1,016 subs of 10 s with the built-in dual-band (LP filter) filter) for a solid image of the Heart Nebula. A quick look takes 42 min; a showpiece 11 h. Under a Bortle 3 rural sky the solid figure drops to 1 h 55 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it is just over the frame at 1.4×.
| Sky | Quick lookTarget obvious, still noisy | SolidClean enough to share | ShowpieceSmooth faint detail, print-worthy |
|---|---|---|---|
| Bortle 1Excellent dark site | 27 min165 subs | 1 h 50 min660 subs | 7 h 20 min2,639 subs |
| Bortle 2Typical dark site | 28 min168 subs | 1 h 52 min671 subs | 7 h 27 min2,683 subs |
| Bortle 3Rural | 29 min173 subs | 1 h 55 min692 subs | 7 h 41 min2,765 subs |
| Bortle 4Rural / suburban transition | 31 min186 subs | 2 h 04 min742 subs | 8 h 14 min2,966 subs |
| Bortle 5Suburban | 34 min206 subs | 2 h 17 min821 subs | 9 h 07 min3,283 subs |
| Bortle 6Bright suburban | 42 min254 subs | 2 h 49 min1,016 subs | 11 h4,062 subs |
| Bortle 7Suburban / urban transition | 58 min347 subs | 3 h 51 min1,387 subs | 15 h5,545 subs |
| Bortle 8City | 1 h 22 min491 subs | 5 h 27 min1,963 subs | 22 h7,849 subs |
| Bortle 9Inner city | 2 h 13 min798 subs | 8 h 52 min3,191 subs | 35 h12,762 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 3 h 40 min of run time. The Seestar S50’s battery is rated at about 6 h, less near freezing, which is cutting it fine; take a power bank. (Bortle 6, solid image; we allow 30% over the integration time, and 30% off the battery for a November night.)
- USB-C power bank 20000mAh 5V 3AThe S50 draws 5 V 3 A over USB-C and runs while charging; no PD needed.
- Seestar S50 dew shieldThe built-in heater copes with most nights; a shield helps in heavy dew and blocks stray light.
- red LED head torchRed light keeps your night vision; white light costs you twenty minutes of dark adaptation every time.
- hand warmers long lastingAir-activated packs give hours of heat for the person; winter nights are long and you spend most of them standing still.
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Everything that fits the Seestar S50 →
How it frames
The Heart Nebula is 60′ across. The Seestar S50 frames 1.28° × 0.72° at 2.39″ per pixel, so it is just over the frame at 1.4×. Point at the part you want; the edges will fall outside the frame.
Longer subs
10, 20 and 30 s in Alt-Az; 60 s only in EQ mode (app 2.5 and later). Time for a solid image by sub length:
| Sub length | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| 10 s | 1 h 55 min692 subs | 2 h 17 min821 subs | 3 h 51 min1,387 subs |
| 20 s | 1 h 22 min245 subs | 1 h 43 min310 subs | 3 h 17 min593 subs |
| 30 s | 1 h 10 min141 subs | 1 h 32 min184 subs | 3 h 06 min373 subs |
| 60 s | 59 min60 subs | 1 h 21 min81 subs | 2 h 55 min175 subs |
With and without the dual-band filter
| Filter | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| UV/IR-cut (no light-pollution filter) | 1 h 40 min602 subs | 2 h 51 min1,025 subs | 7 h 59 min2,873 subs |
| dual-band (LP filter) | 1 h 55 min692 subs | 2 h 17 min821 subs | 3 h 51 min1,387 subs |
About the Heart Nebula
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.
IC 1805, Sh2-190 · Emission nebula in Cassiopeia · magnitude 6.5 · 60′ · best in Oct, Nov, Dec. Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.
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.
About the ZWO Seestar S50
The scope that made smart astrophotography mainstream. 50 mm triplet, 2 MP sensor, dual-band filter on a wheel. Alt-Az stacking at 10 s, EQ mode unlocks 60 s. Out of production since 2026 and replaced by the S50 Pro, but there are a great many in use.
10, 20 and 30 s in Alt-Az; 60 s only in EQ mode (app 2.5 and later). Built-in dual-band light-pollution filter, switchable in the app.
Longer subs matter most under dark skies, where read noise rather than skyglow sets the floor. From a city the difference between 10 s and 60 s subs is small; from a rural site it can halve the total time, especially with a dual-band filter in place.
Stack across nights. Every smart scope app can continue a stack or you can combine the saved frames on a computer; the figures here are totals, not single-session limits.
Have an image of the Heart Nebula from a Seestar S50? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- Heart Nebula with the ZWO Seestar S50 Pro: 3 h 10 min from Bortle 6
- Heart Nebula with the ZWO Seestar S30: 3 h 19 min from Bortle 6
- Heart Nebula with the ZWO Seestar S30 Pro: 3 h 25 min from Bortle 6
- Heart Nebula with the DwarfLab DWARF 3: 3 h 27 min from Bortle 6
- Heart Nebula with the DwarfLab DWARF mini: 2 h 47 min from Bortle 6
- Heart Nebula with the DwarfLab Draco: 2 h 14 min from Bortle 6
- Heart Nebula with the DwarfLab DWARF II: 16 h from Bortle 6
- Heart Nebula with the Vaonis Vespera II: 4 h 37 min from Bortle 6
- Heart Nebula with the Vaonis Vespera Pro: 10 h from Bortle 6
- Heart Nebula with the Vaonis Vespera 3: 4 h 24 min from Bortle 6
- Heart Nebula with the Vaonis Vespera Pro 2: 9 h 52 min from Bortle 6
- Heart Nebula with the Unistellar eQuinox 2: 4 h 14 min from Bortle 6
- Heart Nebula with the Unistellar Odyssey: 20 h from Bortle 6
- Heart Nebula with the Celestron Origin: 1 h 13 min from Bortle 6
- Heart Nebula with the Celestron Origin Mark II: 1 h 40 min from Bortle 6
All telescopes for the Heart Nebula · All targets for the Seestar S50