How long to image the Helix Nebula with the Unistellar Odyssey
From a Bortle 6 suburban sky, the Unistellar Odyssey needs about 14 h (12,341 subs of 4 s) for a solid image of the Helix Nebula. A quick look takes 3 h 26 min; a showpiece 55 h. Under a Bortle 3 rural sky the solid figure drops to 9 h 06 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it fills 74% 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 | 2 h 10 min1,946 subs | 8 h 39 min7,784 subs | 35 h31,135 subs |
| Bortle 2Typical dark site | 2 h 12 min1,981 subs | 8 h 48 min7,924 subs | 35 h31,695 subs |
| Bortle 3Rural | 2 h 16 min2,048 subs | 9 h 06 min8,189 subs | 36 h32,754 subs |
| Bortle 4Rural / suburban transition | 2 h 27 min2,208 subs | 9 h 49 min8,830 subs | 39 h35,319 subs |
| Bortle 5Suburban | 2 h 44 min2,462 subs | 11 h9,847 subs | 44 h39,386 subs |
| Bortle 6Bright suburban | 3 h 26 min3,086 subs | 14 h12,341 subs | 55 h49,362 subs |
| Bortle 7Suburban / urban transition | 4 h 45 min4,274 subs | 19 h17,094 subs | 76 h68,373 subs |
| Bortle 8City | 6 h 48 min6,119 subs | 27 h24,473 subs | 110+ h97,889 subs |
| Bortle 9Inner city | 11 h10,053 subs | 45 h40,210 subs | 180+ h160,837 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 18 h of run time. That is more than one night: over 3 nights, about 5 h 57 min each. The Odyssey’s battery is rated at about 5 h, so each night needs an external power bank. (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 Helix Nebula is 25′ × 22′ across. The Odyssey frames 0.75° × 0.56° at 0.93″ per pixel, so it fills 74% of the frame’s short side.
Filters
The Helix 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 Helix Nebula
The nearest bright planetary nebula, half the Moon's width but spread thin. Low from the UK; dual-band and a couple of hours make the eye appear.
NGC 7293, Caldwell 63 · Planetary nebula in Aquarius · magnitude 7.3 · 25′ × 22′ · best in Aug, Sep, Oct. 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 Helix Nebula from a Odyssey? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- Helix Nebula with the ZWO Seestar S50: 2 h from Bortle 6
- Helix Nebula with the ZWO Seestar S50 Pro: 2 h 15 min from Bortle 6
- Helix Nebula with the ZWO Seestar S30: 2 h 20 min from Bortle 6
- Helix Nebula with the ZWO Seestar S30 Pro: 2 h 25 min from Bortle 6
- Helix Nebula with the DwarfLab DWARF 3: 2 h 28 min from Bortle 6
- Helix Nebula with the DwarfLab DWARF mini: 1 h 58 min from Bortle 6
- Helix Nebula with the DwarfLab Draco: 1 h 35 min from Bortle 6
- Helix Nebula with the DwarfLab DWARF II: 11 h from Bortle 6
- Helix Nebula with the Vaonis Vespera II: 3 h 13 min from Bortle 6
- Helix Nebula with the Vaonis Vespera Pro: 7 h 14 min from Bortle 6
- Helix Nebula with the Vaonis Vespera 3: 3 h 05 min from Bortle 6
- Helix Nebula with the Vaonis Vespera Pro 2: 6 h 53 min from Bortle 6
- Helix Nebula with the Unistellar eQuinox 2: 2 h 57 min from Bortle 6
- Helix Nebula with the Celestron Origin: 51 min from Bortle 6
- Helix Nebula with the Celestron Origin Mark II: 1 h 10 min from Bortle 6
All telescopes for the Helix Nebula · All targets for the Odyssey