How long to image the Bow-Tie Nebula with the DwarfLab DWARF mini
From a Bortle 6 suburban sky, the DwarfLab DWARF mini needs about 21 min (83 subs of 15 s with the built-in dual-band filter) for a solid image of the Bow-Tie Nebula. A quick look takes 5 min; a showpiece 1 h 22 min. Under a Bortle 3 rural sky the solid figure drops to 16 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 12 pixels across.
| Sky | Quick lookTarget obvious, still noisy | SolidClean enough to share | ShowpieceSmooth faint detail, print-worthy |
|---|---|---|---|
| Bortle 1Excellent dark site | 4 min16 subs | 16 min63 subs | 1 h 03 min252 subs |
| Bortle 2Typical dark site | 4 min16 subs | 16 min64 subs | 1 h 04 min255 subs |
| Bortle 3Rural | 4 min17 subs | 16 min65 subs | 1 h 05 min259 subs |
| Bortle 4Rural / suburban transition | 4 min17 subs | 17 min68 subs | 1 h 07 min270 subs |
| Bortle 5Suburban | 4 min18 subs | 18 min72 subs | 1 h 12 min287 subs |
| Bortle 6Bright suburban | 5 min21 subs | 21 min83 subs | 1 h 22 min330 subs |
| Bortle 7Suburban / urban transition | 6 min26 subs | 26 min103 subs | 1 h 43 min411 subs |
| Bortle 8City | 8 min34 subs | 33 min134 subs | 2 h 14 min536 subs |
| Bortle 9Inner city | 13 min51 subs | 50 min201 subs | 3 h 21 min804 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 27 min of run time. The DWARF mini’s battery (rated about 3 h 30 min) 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 PD power bank 10000mAh 20W7,000 mAh inside, about four hours; a PD bank extends the night.
- 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 DWARF mini →
How it frames
The Bow-Tie Nebula is 0.8′ × 0.6′ across. The DWARF mini frames 2.13° × 1.20° at 3.99″ per pixel, so it is small in the frame, about 12 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
Auto mode caps subs at 15 s; 30 s and longer need EQ mode, and 90 s is the ceiling. Time for a solid image by sub length:
| Sub length | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| 15 s | 16 min65 subs | 18 min72 subs | 26 min103 subs |
| 30 s | 15 min30 subs | 15 min31 subs | 23 min46 subs |
| 60 s | 30 min30 subs | 30 min30 subs | 30 min30 subs |
| 90 s | 45 min30 subs | 45 min30 subs | 45 min30 subs |
With and without the dual-band filter
| Filter | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| Astro (no light-pollution filter) | 13 min52 subs | 19 min75 subs | 44 min176 subs |
| dual-band | 16 min65 subs | 18 min72 subs | 26 min103 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 DwarfLab DWARF mini
DwarfLab’s answer to the Seestar S30: same sensor and focal length, big pixels, dual-band filter built in, and 90 s subs in EQ mode. Sensitivity over megapixels.
Auto mode caps subs at 15 s; 30 s and longer need EQ mode, and 90 s is the ceiling. Built-in Astro (430 to 690 nm), dark-frame and dual-band Hα / OIII filters; no plain VIS filter on the tele camera.
Longer subs matter most under dark skies, where read noise rather than skyglow sets the floor. From a city the difference between 15 s and 90 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 DWARF mini? 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 ZWO Seestar S30 Pro: 25 min from Bortle 6
- Bow-Tie Nebula with the DwarfLab DWARF 3: 28 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 DWARF mini