How long to image the Jellyfish Nebula with the ZWO Seestar S30
From a Bortle 6 suburban sky, the ZWO Seestar S30 needs about 4 h 43 min (1,696 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 11 min; a showpiece 19 h. Under a Bortle 3 rural sky the solid figure drops to 3 h 24 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it fills 70% 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 | 49 min296 subs | 3 h 17 min1,182 subs | 13 h4,725 subs |
| Bortle 2Typical dark site | 50 min300 subs | 3 h 19 min1,197 subs | 13 h4,788 subs |
| Bortle 3Rural | 51 min307 subs | 3 h 24 min1,227 subs | 14 h4,908 subs |
| Bortle 4Rural / suburban transition | 54 min325 subs | 3 h 37 min1,300 subs | 14 h5,197 subs |
| Bortle 5Suburban | 59 min354 subs | 3 h 56 min1,414 subs | 16 h5,656 subs |
| Bortle 6Bright suburban | 1 h 11 min424 subs | 4 h 43 min1,696 subs | 19 h6,782 subs |
| Bortle 7Suburban / urban transition | 1 h 33 min558 subs | 6 h 12 min2,232 subs | 25 h8,926 subs |
| Bortle 8City | 2 h 08 min766 subs | 8 h 31 min3,064 subs | 34 h12,256 subs |
| Bortle 9Inner city | 3 h 22 min1,210 subs | 13 h4,840 subs | 54 h19,358 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 6 h 07 min of run time. The Seestar S30’s battery is rated at about 6 h, less near freezing, so the session needs an external power bank. (Bortle 6, solid image; we allow 30% over the integration time, and 30% off the battery for a January night.)
- USB-C power bank 10000mAh 5V 3A6,000 mAh inside; a 10,000 mAh 5 V 3 A bank roughly doubles a session.
- Seestar S30 dew shieldHeater is built in; a cheap shield reduces dew and 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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How it frames
The Jellyfish Nebula is 50′ × 40′ across. The Seestar S30 frames 2.13° × 1.20° at 3.99″ per pixel, so it fills 70% of the frame’s short side.
Longer subs
10, 20 and 30 s in Alt-Az; 60 s only in EQ mode, which needs the TH10 head. Time for a solid image by sub length:
| Sub length | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| 10 s | 3 h 24 min1,227 subs | 3 h 56 min1,414 subs | 6 h 12 min2,232 subs |
| 20 s | 2 h 14 min404 subs | 2 h 46 min497 subs | 5 h 02 min906 subs |
| 30 s | 1 h 51 min223 subs | 2 h 22 min285 subs | 4 h 38 min557 subs |
| 60 s | 1 h 28 min88 subs | 1 h 59 min119 subs | 4 h 15 min256 subs |
With and without the dual-band filter
| Filter | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| UV/IR-cut (no light-pollution filter) | 2 h 43 min976 subs | 4 h 24 min1,587 subs | 12 h4,257 subs |
| dual-band (LP filter) | 3 h 24 min1,227 subs | 3 h 56 min1,414 subs | 6 h 12 min2,232 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 S30
Wider and lighter than the S50 with the same 2.9 µm pixels, so its per-pixel speed on extended targets is close despite the smaller aperture. Ideal for big nebulae.
10, 20 and 30 s in Alt-Az; 60 s only in EQ mode, which needs the TH10 head. Built-in UV/IR-cut, dual-band (OIII 30 nm / Hα 20 nm) and dark filters.
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 S30? 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 S50 Pro: 4 h 30 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 S30