How long to image the Iris Nebula with the Unistellar Odyssey
From a Bortle 6 suburban sky, the Unistellar Odyssey needs about 7 h 58 min (7,175 subs of 4 s) for a solid image of the Iris Nebula. A quick look takes 2 h; a showpiece 32 h. Under a Bortle 3 rural sky the solid figure drops to 5 h 19 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it fills 53% 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 | 1 h 16 min1,138 subs | 5 h 03 min4,552 subs | 20 h18,208 subs |
| Bortle 2Typical dark site | 1 h 17 min1,159 subs | 5 h 09 min4,633 subs | 21 h18,530 subs |
| Bortle 3Rural | 1 h 20 min1,197 subs | 5 h 19 min4,785 subs | 21 h19,140 subs |
| Bortle 4Rural / suburban transition | 1 h 26 min1,289 subs | 5 h 44 min5,154 subs | 23 h20,616 subs |
| Bortle 5Suburban | 1 h 36 min1,435 subs | 6 h 23 min5,739 subs | 26 h22,956 subs |
| Bortle 6Bright suburban | 2 h1,794 subs | 7 h 58 min7,175 subs | 32 h28,697 subs |
| Bortle 7Suburban / urban transition | 2 h 45 min2,478 subs | 11 h9,909 subs | 44 h39,636 subs |
| Bortle 8City | 3 h 56 min3,539 subs | 16 h14,156 subs | 63 h56,621 subs |
| Bortle 9Inner city | 6 h 27 min5,803 subs | 26 h23,211 subs | 100+ h92,844 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 10 h of run time. That is more than one night: over 2 nights, about 5 h 11 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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Everything that fits the Odyssey →
How it frames
The Iris Nebula is 18′ across. The Odyssey frames 0.75° × 0.56° at 0.93″ per pixel, so it fills 53% of the frame’s short side.
About the Iris Nebula
A blue reflection nebula wrapped in dark dust. No filter helps, and the surrounding dust needs a dark sky and hours.
NGC 7023, Caldwell 4 · Reflection nebula in Cepheus · magnitude 6.8 · 18′ · best in Jul, Aug, Sep. Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.
Reflection nebulae are starlight scattered by dust, so they are broadband and blue. A dual-band filter removes almost all of it; do not use one. These are among the faintest structures a smart scope can attempt and the figures run long. A dark sky matters more here than for any other type, and the Moon must be down.
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 Iris Nebula from a Odyssey? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- Iris Nebula with the ZWO Seestar S50: 1 h 53 min from Bortle 6
- Iris Nebula with the ZWO Seestar S50 Pro: 2 h 04 min from Bortle 6
- Iris Nebula with the ZWO Seestar S30: 1 h 59 min from Bortle 6
- Iris Nebula with the ZWO Seestar S30 Pro: 2 h 12 min from Bortle 6
- Iris Nebula with the DwarfLab DWARF 3: 2 h 45 min from Bortle 6
- Iris Nebula with the DwarfLab DWARF mini: 1 h 53 min from Bortle 6
- Iris Nebula with the DwarfLab Draco: 1 h 33 min from Bortle 6
- Iris Nebula with the DwarfLab DWARF II: 6 h 29 min from Bortle 6
- Iris Nebula with the Vaonis Vespera II: 1 h 53 min from Bortle 6
- Iris Nebula with the Vaonis Vespera Pro: 4 h 14 min from Bortle 6
- Iris Nebula with the Vaonis Vespera 3: 1 h 48 min from Bortle 6
- Iris Nebula with the Vaonis Vespera Pro 2: 4 h 02 min from Bortle 6
- Iris Nebula with the Unistellar eQuinox 2: 1 h 43 min from Bortle 6
- Iris Nebula with the Celestron Origin: 30 min from Bortle 6
- Iris Nebula with the Celestron Origin Mark II: 41 min from Bortle 6
All telescopes for the Iris Nebula · All targets for the Odyssey