How long to image the Bow-Tie Nebula with the Unistellar eQuinox 2
From a Bortle 6 suburban sky, the Unistellar eQuinox 2 needs about 24 min (358 subs of 4 s) for a solid image of the Bow-Tie Nebula. A quick look takes 6 min; a showpiece 1 h 35 min. Under a Bortle 3 rural sky the solid figure drops to 15 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 36 pixels across.
| Sky | Quick lookTarget obvious, still noisy | SolidClean enough to share | ShowpieceSmooth faint detail, print-worthy |
|---|---|---|---|
| Bortle 1Excellent dark site | 3 min53 subs | 14 min210 subs | 56 min838 subs |
| Bortle 2Typical dark site | 4 min54 subs | 14 min214 subs | 57 min856 subs |
| Bortle 3Rural | 4 min56 subs | 15 min223 subs | 59 min890 subs |
| Bortle 4Rural / suburban transition | 4 min61 subs | 16 min244 subs | 1 h 05 min973 subs |
| Bortle 5Suburban | 5 min70 subs | 18 min277 subs | 1 h 14 min1,105 subs |
| Bortle 6Bright suburban | 6 min90 subs | 24 min358 subs | 1 h 35 min1,429 subs |
| Bortle 7Suburban / urban transition | 9 min128 subs | 34 min512 subs | 2 h 16 min2,046 subs |
| Bortle 8City | 13 min188 subs | 50 min751 subs | 3 h 20 min3,004 subs |
| Bortle 9Inner city | 21 min316 subs | 1 h 24 min1,262 subs | 5 h 36 min5,047 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 31 min of run time. The eQuinox 2’s battery (rated about 11 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 20000mAh 5V 2AUnistellar asks for a 5 V 2 A output; PD is not needed.
- 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 eQuinox 2 →
How it frames
The Bow-Tie Nebula is 0.8′ × 0.6′ across. The eQuinox 2 frames 0.76° × 0.57° at 1.33″ per pixel, so it is small in the frame, about 36 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.
Filters
The Bow-Tie Nebula is an emission target, where a dual-band filter would normally cut the time several-fold from a lit sky, but the eQuinox 2 has no dual-band option: No built-in filter. Unistellar sells only a solar filter and says a third-party filter is at your own risk and voids the warranty. The figures above are for the No filter position, and a darker sky is the lever that remains.
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 Unistellar eQuinox 2
A 114 mm Newtonian with five times the light grasp of a 50 mm refractor. Fixed 4 s subs put it in read-noise territory under dark skies, but the aperture carries it. The published field is 45.6′ × 34.2′, a crop of the sensor.
Fixed 4 s subs in Enhanced Vision; they cannot be changed. No built-in filter. Unistellar sells only a solar filter and says a third-party filter is at your own risk and voids the warranty.
The eQuinox 2 uses fixed 4 s subs, so the only levers you have are the sky you shoot from, the filter, and total time.
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 eQuinox 2? 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 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 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 eQuinox 2