How long to image the Bow-Tie Nebula with the Unistellar Odyssey
From a Bortle 6 suburban sky, the Unistellar Odyssey needs about 1 h 48 min (1,616 subs of 4 s) for a solid image of the Bow-Tie Nebula. A quick look takes 27 min; a showpiece 7 h 11 min. Under a Bortle 3 rural sky the solid figure drops to 1 h 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 51 pixels across.
| Sky | Quick lookTarget obvious, still noisy | SolidClean enough to share | ShowpieceSmooth faint detail, print-worthy |
|---|---|---|---|
| Bortle 1Excellent dark site | 18 min270 subs | 1 h 12 min1,078 subs | 4 h 47 min4,310 subs |
| Bortle 2Typical dark site | 18 min274 subs | 1 h 13 min1,094 subs | 4 h 52 min4,376 subs |
| Bortle 3Rural | 19 min282 subs | 1 h 15 min1,126 subs | 5 h4,501 subs |
| Bortle 4Rural / suburban transition | 20 min301 subs | 1 h 20 min1,201 subs | 5 h 20 min4,804 subs |
| Bortle 5Suburban | 22 min331 subs | 1 h 28 min1,321 subs | 5 h 52 min5,284 subs |
| Bortle 6Bright suburban | 27 min404 subs | 1 h 48 min1,616 subs | 7 h 11 min6,462 subs |
| Bortle 7Suburban / urban transition | 36 min545 subs | 2 h 25 min2,177 subs | 9 h 40 min8,707 subs |
| Bortle 8City | 51 min762 subs | 3 h 23 min3,048 subs | 14 h12,192 subs |
| Bortle 9Inner city | 1 h 22 min1,227 subs | 5 h 27 min4,907 subs | 22 h19,625 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 2 h 20 min of run time. The Odyssey’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 power bank 20000mAh 5V 2.4AUnistellar says plain 5 V 2.4 A and warns against fast or adaptive chargers.
- 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 Odyssey frames 0.75° × 0.56° at 0.93″ per pixel, so it is small in the frame, about 51 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 Odyssey has no dual-band option: No filter option; Unistellar says third-party filters cannot be fitted to the Odyssey. 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 Odyssey
Unistellar’s compact 85 mm with autofocus and tiny pixels. Sharp, but the fine sampling costs time on faint extended targets. The Odyssey Pro is the same telescope with an eyepiece added, so these figures apply to both.
Fixed 4 s subs in Enhanced Vision; they cannot be changed. No filter option; Unistellar says third-party filters cannot be fitted to the Odyssey.
The Odyssey 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 Odyssey? 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 eQuinox 2: 24 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 Odyssey