How long to image the Bow-Tie Nebula with the ZWO Seestar S30 Pro
From a Bortle 6 suburban sky, the ZWO Seestar S30 Pro needs about 25 min (149 subs of 10 s with the built-in dual-band (LP filter) filter) for a solid image of the Bow-Tie Nebula. A quick look takes 6 min; a showpiece 1 h 39 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 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 | 5 min29 subs | 19 min116 subs | 1 h 17 min461 subs |
| Bortle 2Typical dark site | 5 min30 subs | 19 min117 subs | 1 h 17 min465 subs |
| Bortle 3Rural | 5 min30 subs | 20 min119 subs | 1 h 19 min473 subs |
| Bortle 4Rural / suburban transition | 5 min31 subs | 20 min123 subs | 1 h 22 min491 subs |
| Bortle 5Suburban | 5 min33 subs | 22 min131 subs | 1 h 27 min521 subs |
| Bortle 6Bright suburban | 6 min38 subs | 25 min149 subs | 1 h 39 min593 subs |
| Bortle 7Suburban / urban transition | 8 min46 subs | 30 min183 subs | 2 h 02 min731 subs |
| Bortle 8City | 10 min60 subs | 39 min237 subs | 2 h 37 min945 subs |
| Bortle 9Inner city | 15 min88 subs | 58 min351 subs | 3 h 54 min1,402 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 32 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.)
- 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.
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How it frames
The Bow-Tie Nebula is 0.8′ × 0.6′ 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 | 20 min119 subs | 22 min131 subs | 30 min183 subs |
| 20 s | 16 min49 subs | 18 min55 subs | 27 min81 subs |
| 30 s | 15 min30 subs | 17 min34 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) | 15 min93 subs | 22 min132 subs | 51 min304 subs |
| dual-band (LP filter) | 20 min119 subs | 22 min131 subs | 30 min183 subs |
About the Bow-Tie Nebula
A red-tinged planetary near the pole with a bright central star. Small; dual-band brings out the bow.
NGC 40, Caldwell 2 · Planetary nebula in Cepheus · magnitude 11.6 · 0.8′ × 0.6′ · best in Sep, Oct, Nov. 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 Bow-Tie 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
- Bow-Tie Nebula with the ZWO Seestar S50: 21 min from Bortle 6
- Bow-Tie Nebula with the ZWO Seestar S50 Pro: 23 min from Bortle 6
- Bow-Tie Nebula with the ZWO Seestar S30: 23 min from Bortle 6
- Bow-Tie Nebula with the DwarfLab DWARF 3: 28 min from Bortle 6
- Bow-Tie Nebula with the DwarfLab DWARF mini: 21 min from Bortle 6
- Bow-Tie Nebula with the DwarfLab Draco: 17 min from Bortle 6
- Bow-Tie Nebula with the DwarfLab DWARF II: 1 h 32 min from Bortle 6
- Bow-Tie Nebula with the Vaonis Vespera II: 27 min from Bortle 6
- Bow-Tie Nebula with the Vaonis Vespera Pro: 1 h 01 min from Bortle 6
- Bow-Tie Nebula with the Vaonis Vespera 3: 26 min from Bortle 6
- Bow-Tie Nebula with the Vaonis Vespera Pro 2: 58 min from Bortle 6
- Bow-Tie Nebula with the Unistellar eQuinox 2: 24 min from Bortle 6
- Bow-Tie Nebula with the Unistellar Odyssey: 1 h 48 min from Bortle 6
- Bow-Tie Nebula with the Celestron Origin: 7 min from Bortle 6
- Bow-Tie Nebula with the Celestron Origin Mark II: 10 min from Bortle 6
All telescopes for the Bow-Tie Nebula · All targets for the Seestar S30 Pro