How long to image the Jellyfish Nebula with the ZWO Seestar S50 Pro
From a Bortle 6 suburban sky, the ZWO Seestar S50 Pro needs about 4 h 30 min (1,618 subs of 10 s with the built-in dual-band (LP filter) filter) for a solid image of the Jellyfish Nebula. A quick look takes 1 h 07 min; a showpiece 18 h. Under a Bortle 3 rural sky the solid figure drops to 3 h 05 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it fills 60% of the frame’s short side.
| Sky | Quick lookTarget obvious, still noisy | SolidClean enough to share | ShowpieceSmooth faint detail, print-worthy |
|---|---|---|---|
| Bortle 1Excellent dark site | 44 min266 subs | 2 h 57 min1,062 subs | 12 h4,246 subs |
| Bortle 2Typical dark site | 45 min270 subs | 3 h1,079 subs | 12 h4,315 subs |
| Bortle 3Rural | 46 min278 subs | 3 h 05 min1,111 subs | 12 h4,444 subs |
| Bortle 4Rural / suburban transition | 50 min298 subs | 3 h 18 min1,190 subs | 13 h4,757 subs |
| Bortle 5Suburban | 55 min329 subs | 3 h 39 min1,314 subs | 15 h5,253 subs |
| Bortle 6Bright suburban | 1 h 07 min405 subs | 4 h 30 min1,618 subs | 18 h6,470 subs |
| Bortle 7Suburban / urban transition | 1 h 32 min550 subs | 6 h 06 min2,198 subs | 24 h8,790 subs |
| Bortle 8City | 2 h 09 min775 subs | 8 h 36 min3,098 subs | 34 h12,392 subs |
| Bortle 9Inner city | 3 h 29 min1,255 subs | 14 h5,019 subs | 56 h20,073 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 5 h 50 min of run time. The Seestar S50 Pro’s battery is rated at about 9 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 January night.)
- USB-C PD power bank 20000mAh 30WAccepts 12 V 3 A PD, so a 30 W bank tops up the 10,000 mAh cell while imaging.
- Seestar S50 Pro dew shieldDew heater is built in; a shield adds margin on damp nights. Check the listing says S50 Pro.
- 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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How it frames
The Jellyfish Nebula is 50′ × 40′ across. The Seestar S50 Pro frames 2.45° × 1.38° at 2.30″ per pixel, so it fills 60% of the frame’s short side.
Longer subs
10, 20 and 30 s in Alt-Az; 60 s only in EQ mode, and 60 s is the ceiling. Time for a solid image by sub length:
| Sub length | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| 10 s | 3 h 05 min1,111 subs | 3 h 39 min1,314 subs | 6 h 06 min2,198 subs |
| 20 s | 2 h 08 min385 subs | 2 h 42 min486 subs | 5 h 09 min928 subs |
| 30 s | 1 h 49 min219 subs | 2 h 23 min286 subs | 4 h 50 min581 subs |
| 60 s | 1 h 30 min91 subs | 2 h 04 min124 subs | 4 h 31 min272 subs |
With and without the dual-band filter
| Filter | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| UV/IR-cut (no light-pollution filter) | 2 h 38 min949 subs | 4 h 28 min1,610 subs | 12 h4,499 subs |
| dual-band (LP filter) | 3 h 05 min1,111 subs | 3 h 39 min1,314 subs | 6 h 06 min2,198 subs |
About the Jellyfish Nebula
A supernova remnant beside Propus in Gemini, with a bright rim like a jellyfish bell. Faint; dual-band and hours.
IC 443, Sh2-248 · Supernova remnant in Gemini · magnitude 12.0 · 50′ × 40′ · best in Dec, Jan, Feb. Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.
Supernova remnants are emission-line objects, strong in both hydrogen-alpha and OIII, and their filaments are thin, so pixel scale matters as much as aperture. A dual-band filter is essential from any lit sky and still helps under a dark one. These are long-integration targets; plan on several sessions and stack across nights.
About the ZWO Seestar S50 Pro
The S50 optics at 260 mm on an 8 MP 1/1.2-inch sensor: a wider, taller field, four times the pixels, and 60 s subs in EQ mode. Per pixel it is a whisker slower than the S50 because of the longer focal length; the long subs make it the better dark-site scope.
10, 20 and 30 s in Alt-Az; 60 s only in EQ mode, and 60 s is the ceiling. Built-in UV/IR-cut, dual-band (OIII 30 nm / Hα 20 nm) and dark filters on the telephoto camera.
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 Jellyfish Nebula from a Seestar S50 Pro? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- Jellyfish Nebula with the ZWO Seestar S50: 4 h from Bortle 6
- Jellyfish Nebula with the ZWO Seestar S30: 4 h 43 min from Bortle 6
- Jellyfish Nebula with the ZWO Seestar S30 Pro: 4 h 51 min from Bortle 6
- Jellyfish Nebula with the DwarfLab DWARF 3: 4 h 52 min from Bortle 6
- Jellyfish Nebula with the DwarfLab DWARF mini: 3 h 56 min from Bortle 6
- Jellyfish Nebula with the DwarfLab Draco: 3 h 09 min from Bortle 6
- Jellyfish Nebula with the DwarfLab DWARF II: 23 h from Bortle 6
- Jellyfish Nebula with the Vaonis Vespera II: 6 h 37 min from Bortle 6
- Jellyfish Nebula with the Vaonis Vespera Pro: 15 h from Bortle 6
- Jellyfish Nebula with the Vaonis Vespera 3: 6 h 19 min from Bortle 6
- Jellyfish Nebula with the Vaonis Vespera Pro 2: 14 h from Bortle 6
- Jellyfish Nebula with the Unistellar eQuinox 2: 6 h 05 min from Bortle 6
- Jellyfish Nebula with the Unistellar Odyssey: 28 h from Bortle 6
- Jellyfish Nebula with the Celestron Origin: 1 h 45 min from Bortle 6
- Jellyfish Nebula with the Celestron Origin Mark II: 2 h 23 min from Bortle 6
All telescopes for the Jellyfish Nebula · All targets for the Seestar S50 Pro