How long to image the Omega Nebula with the ZWO Seestar S30
From a Bortle 6 suburban sky, the ZWO Seestar S30 needs about 26 min (157 subs of 10 s with the built-in dual-band (LP filter) filter) for a solid image of the Omega Nebula. A quick look takes 7 min; a showpiece 1 h 44 min. Under a Bortle 3 rural sky the solid figure drops to 20 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it fills 15% 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 | 5 min30 subs | 20 min120 subs | 1 h 20 min478 subs |
| Bortle 2Typical dark site | 5 min31 subs | 20 min121 subs | 1 h 20 min483 subs |
| Bortle 3Rural | 5 min31 subs | 20 min123 subs | 1 h 22 min491 subs |
| Bortle 4Rural / suburban transition | 5 min32 subs | 21 min128 subs | 1 h 25 min512 subs |
| Bortle 5Suburban | 6 min35 subs | 23 min137 subs | 1 h 31 min545 subs |
| Bortle 6Bright suburban | 7 min40 subs | 26 min157 subs | 1 h 44 min625 subs |
| Bortle 7Suburban / urban transition | 8 min49 subs | 32 min195 subs | 2 h 10 min779 subs |
| Bortle 8City | 11 min64 subs | 42 min255 subs | 2 h 49 min1,017 subs |
| Bortle 9Inner city | 16 min96 subs | 1 h 04 min382 subs | 4 h 14 min1,526 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 34 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 Omega Nebula is 11′ across. The Seestar S30 frames 2.13° × 1.20° at 3.99″ per pixel, so it fills 15% 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 | 20 min123 subs | 23 min137 subs | 32 min195 subs |
| 20 s | 15 min47 subs | 18 min54 subs | 27 min83 subs |
| 30 s | 15 min30 subs | 16 min32 subs | 26 min52 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) | 16 min95 subs | 23 min138 subs | 55 min330 subs |
| dual-band (LP filter) | 20 min123 subs | 23 min137 subs | 32 min195 subs |
About the Omega Nebula
A bright, compact swan-shaped emission nebula, one of the brightest in the sky per unit area. Excellent from suburban skies.
M17, NGC 6618, Swan Nebula · Emission nebula in Sagittarius · magnitude 6.0 · 11′ · best in Jun, Jul, Aug. 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 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 Omega 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
- Omega Nebula with the ZWO Seestar S50: 23 min from Bortle 6
- Omega Nebula with the ZWO Seestar S50 Pro: 26 min from Bortle 6
- Omega Nebula with the ZWO Seestar S30 Pro: 27 min from Bortle 6
- Omega Nebula with the DwarfLab DWARF 3: 30 min from Bortle 6
- Omega Nebula with the DwarfLab DWARF mini: 23 min from Bortle 6
- Omega Nebula with the DwarfLab Draco: 18 min from Bortle 6
- Omega Nebula with the DwarfLab DWARF II: 1 h 49 min from Bortle 6
- Omega Nebula with the Vaonis Vespera II: 32 min from Bortle 6
- Omega Nebula with the Vaonis Vespera Pro: 1 h 12 min from Bortle 6
- Omega Nebula with the Vaonis Vespera 3: 31 min from Bortle 6
- Omega Nebula with the Vaonis Vespera Pro 2: 1 h 09 min from Bortle 6
- Omega Nebula with the Unistellar eQuinox 2: 29 min from Bortle 6
- Omega Nebula with the Unistellar Odyssey: 2 h 11 min from Bortle 6
- Omega Nebula with the Celestron Origin: 9 min from Bortle 6
- Omega Nebula with the Celestron Origin Mark II: 12 min from Bortle 6
All telescopes for the Omega Nebula · All targets for the Seestar S30