How long to image the Eskimo Nebula with the ZWO Seestar S30 Pro
From a Bortle 6 suburban sky, the ZWO Seestar S30 Pro needs about 12 min (73 subs of 10 s with the built-in dual-band (LP filter) filter) for a solid image of the Eskimo Nebula. A quick look takes 3 min; a showpiece 48 min. Under a Bortle 3 rural sky the solid figure drops to 10 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 13 pixels across.
| Sky | Quick lookTarget obvious, still noisy | SolidClean enough to share | ShowpieceSmooth faint detail, print-worthy |
|---|---|---|---|
| Bortle 1Excellent dark site | 2 min15 subs | 10 min60 subs | 40 min239 subs |
| Bortle 2Typical dark site | 2 min15 subs | 10 min60 subs | 40 min240 subs |
| Bortle 3Rural | 3 min16 subs | 10 min61 subs | 40 min243 subs |
| Bortle 4Rural / suburban transition | 3 min16 subs | 10 min63 subs | 42 min251 subs |
| Bortle 5Suburban | 3 min17 subs | 11 min66 subs | 44 min263 subs |
| Bortle 6Bright suburban | 3 min19 subs | 12 min73 subs | 48 min291 subs |
| Bortle 7Suburban / urban transition | 4 min22 subs | 14 min87 subs | 58 min346 subs |
| Bortle 8City | 4 min27 subs | 18 min108 subs | 1 h 12 min431 subs |
| Bortle 9Inner city | 6 min39 subs | 26 min154 subs | 1 h 42 min613 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 16 min of run time. The Seestar S30 Pro’s battery (rated about 5 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, and 30% off the battery for a January night.)
- USB-C power bank 10000mAh 5V 3A5 V 3 A input and it runs while charging.
- Seestar S30 Pro dew shieldActive anti-dew is built in; a shield adds margin. The S30 Pro front differs from the S30, so check the listing.
- 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 S30 Pro →
How it frames
The Eskimo Nebula is 0.8′ × 0.7′ across. The Seestar S30 Pro frames 3.99° × 2.24° at 3.74″ per pixel, so it is small in the frame, about 13 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 | 10 min61 subs | 11 min66 subs | 14 min87 subs |
| 20 s | 10 min30 subs | 10 min30 subs | 13 min39 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) | 8 min47 subs | 10 min62 subs | 22 min131 subs |
| dual-band (LP filter) | 10 min61 subs | 11 min66 subs | 14 min87 subs |
About the Eskimo Nebula
A small, bright double-shell planetary in Gemini. Tiny in a smart scope but intense; a few minutes show the disc.
NGC 2392, Caldwell 39, Clown Face · Planetary nebula in Gemini · magnitude 9.2 · 0.8′ × 0.7′ · best in Dec, Jan, Feb. 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 Pro
The S30 optics upgraded to a quadruplet in front of an 8 MP IMX585. Same speed per pixel as the S30, four times the pixels, so you can crop hard.
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 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 Eskimo Nebula from a Seestar S30 Pro? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- Eskimo Nebula with the ZWO Seestar S50: 10 min from Bortle 6
- Eskimo Nebula with the ZWO Seestar S50 Pro: 11 min from Bortle 6
- Eskimo Nebula with the ZWO Seestar S30: 11 min from Bortle 6
- Eskimo Nebula with the DwarfLab DWARF 3: 14 min from Bortle 6
- Eskimo Nebula with the DwarfLab DWARF mini: 10 min from Bortle 6
- Eskimo Nebula with the DwarfLab Draco: 15 min from Bortle 6
- Eskimo Nebula with the DwarfLab DWARF II: 40 min from Bortle 6
- Eskimo Nebula with the Vaonis Vespera II: 12 min from Bortle 6
- Eskimo Nebula with the Vaonis Vespera Pro: 27 min from Bortle 6
- Eskimo Nebula with the Vaonis Vespera 3: 12 min from Bortle 6
- Eskimo Nebula with the Vaonis Vespera Pro 2: 26 min from Bortle 6
- Eskimo Nebula with the Unistellar eQuinox 2: 10 min from Bortle 6
- Eskimo Nebula with the Unistellar Odyssey: 46 min from Bortle 6
- Eskimo Nebula with the Celestron Origin: 5 min from Bortle 6
- Eskimo Nebula with the Celestron Origin Mark II: 5 min from Bortle 6
All telescopes for the Eskimo Nebula · All targets for the Seestar S30 Pro