How long to image the Ghost of Jupiter with the ZWO Seestar S30
From a Bortle 6 suburban sky, the ZWO Seestar S30 needs about 11 min (68 subs of 10 s with the built-in dual-band (LP filter) filter) for a solid image of the Ghost of Jupiter. A quick look takes 3 min; a showpiece 45 min. Under a Bortle 3 rural sky the solid figure drops to 9 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it is small in the frame, about 6 pixels across.
| Sky | Quick lookTarget obvious, still noisy | SolidClean enough to share | ShowpieceSmooth faint detail, print-worthy |
|---|---|---|---|
| Bortle 1Excellent dark site | 2 min14 subs | 9 min56 subs | 37 min224 subs |
| Bortle 2Typical dark site | 2 min15 subs | 9 min57 subs | 38 min226 subs |
| Bortle 3Rural | 2 min15 subs | 9 min57 subs | 38 min228 subs |
| Bortle 4Rural / suburban transition | 2 min15 subs | 10 min59 subs | 39 min235 subs |
| Bortle 5Suburban | 3 min16 subs | 10 min62 subs | 41 min245 subs |
| Bortle 6Bright suburban | 3 min17 subs | 11 min68 subs | 45 min271 subs |
| Bortle 7Suburban / urban transition | 3 min20 subs | 13 min80 subs | 53 min319 subs |
| Bortle 8City | 4 min25 subs | 16 min99 subs | 1 h 06 min394 subs |
| Bortle 9Inner city | 6 min35 subs | 23 min139 subs | 1 h 32 min554 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 15 min of run time. The Seestar S30’s battery (rated about 6 h) should cover it; a power bank still keeps the phone running the app alive. (Bortle 6, solid image; we allow 30% over the integration time.)
- 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.
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Everything that fits the Seestar S30 →
How it frames
The Ghost of Jupiter is 0.42′ × 0.35′ across. The Seestar S30 frames 2.13° × 1.20° at 3.99″ per pixel, so it is small in the frame, about 6 pixels across. It is worth doing, but the result is a crop rather than a full frame; a longer focal length would resolve more of it.
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 | 9 min57 subs | 10 min62 subs | 13 min80 subs |
| 20 s | 10 min30 subs | 10 min30 subs | 12 min36 subs |
| 30 s | 15 min30 subs | 15 min30 subs | 15 min30 subs |
| 60 s | 30 min30 subs | 30 min30 subs | 30 min30 subs |
With and without the dual-band filter
| Filter | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| UV/IR-cut (no light-pollution filter) | 7 min43 subs | 9 min57 subs | 19 min117 subs |
| dual-band (LP filter) | 9 min57 subs | 10 min62 subs | 13 min80 subs |
About the Ghost of Jupiter
A bright, blue-green planetary the apparent size of Jupiter. Very bright per pixel; keep subs short.
NGC 3242, Caldwell 59 · Planetary nebula in Hydra · magnitude 7.7 · 0.42′ × 0.35′ · best in Feb, Mar, Apr. Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.
Planetary nebulae are small but intensely bright per pixel in OIII and H-alpha, so they respond very well to a dual-band filter and do not need much time for the main shell. The faint outer halos most of them have are a different proposition and need hours. Keep subs short if the central region saturates.
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 Ghost of Jupiter from a Seestar S30? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- Ghost of Jupiter with the ZWO Seestar S50: 10 min from Bortle 6
- Ghost of Jupiter with the ZWO Seestar S50 Pro: 11 min from Bortle 6
- Ghost of Jupiter with the ZWO Seestar S30 Pro: 12 min from Bortle 6
- Ghost of Jupiter with the DwarfLab DWARF 3: 14 min from Bortle 6
- Ghost of Jupiter with the DwarfLab DWARF mini: 10 min from Bortle 6
- Ghost of Jupiter with the DwarfLab Draco: 15 min from Bortle 6
- Ghost of Jupiter with the DwarfLab DWARF II: 40 min from Bortle 6
- Ghost of Jupiter with the Vaonis Vespera II: 12 min from Bortle 6
- Ghost of Jupiter with the Vaonis Vespera Pro: 27 min from Bortle 6
- Ghost of Jupiter with the Vaonis Vespera 3: 12 min from Bortle 6
- Ghost of Jupiter with the Vaonis Vespera Pro 2: 26 min from Bortle 6
- Ghost of Jupiter with the Unistellar eQuinox 2: 10 min from Bortle 6
- Ghost of Jupiter with the Unistellar Odyssey: 46 min from Bortle 6
- Ghost of Jupiter with the Celestron Origin: 5 min from Bortle 6
- Ghost of Jupiter with the Celestron Origin Mark II: 5 min from Bortle 6
All telescopes for the Ghost of Jupiter · All targets for the Seestar S30