How long to image the Turtle Nebula with the Unistellar Odyssey
From a Bortle 6 suburban sky, the Unistellar Odyssey needs about 46 min (691 subs of 4 s) for a solid image of the Turtle Nebula. A quick look takes 12 min; a showpiece 3 h 04 min. Under a Bortle 3 rural sky the solid figure drops to 33 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 19 pixels across.
| Sky | Quick lookTarget obvious, still noisy | SolidClean enough to share | ShowpieceSmooth faint detail, print-worthy |
|---|---|---|---|
| Bortle 1Excellent dark site | 8 min120 subs | 32 min477 subs | 2 h 07 min1,907 subs |
| Bortle 2Typical dark site | 8 min121 subs | 32 min484 subs | 2 h 09 min1,934 subs |
| Bortle 3Rural | 8 min124 subs | 33 min496 subs | 2 h 12 min1,983 subs |
| Bortle 4Rural / suburban transition | 9 min132 subs | 35 min526 subs | 2 h 20 min2,104 subs |
| Bortle 5Suburban | 10 min144 subs | 38 min574 subs | 2 h 33 min2,295 subs |
| Bortle 6Bright suburban | 12 min173 subs | 46 min691 subs | 3 h 04 min2,764 subs |
| Bortle 7Suburban / urban transition | 15 min229 subs | 1 h 01 min915 subs | 4 h 04 min3,658 subs |
| Bortle 8City | 21 min316 subs | 1 h 24 min1,262 subs | 5 h 36 min5,045 subs |
| Bortle 9Inner city | 33 min501 subs | 2 h 13 min2,001 subs | 8 h 54 min8,004 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 1 h 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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Everything that fits the Odyssey →
How it frames
The Turtle Nebula is 0.3′ across. The Odyssey frames 0.75° × 0.56° at 0.93″ per pixel, so it is small in the frame, about 19 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 Turtle 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 Turtle Nebula
A tiny, very bright planetary in Hercules. A blue-green star-like blob in a smart scope, but an easy catch.
NGC 6210 · Planetary nebula in Hercules · magnitude 9.0 · 0.3′ · best in May, Jun, Jul. 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 Turtle Nebula from a Odyssey? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- Turtle Nebula with the ZWO Seestar S50: 10 min from Bortle 6
- Turtle Nebula with the ZWO Seestar S50 Pro: 11 min from Bortle 6
- Turtle Nebula with the ZWO Seestar S30: 11 min from Bortle 6
- Turtle Nebula with the ZWO Seestar S30 Pro: 12 min from Bortle 6
- Turtle Nebula with the DwarfLab DWARF 3: 14 min from Bortle 6
- Turtle Nebula with the DwarfLab DWARF mini: 10 min from Bortle 6
- Turtle Nebula with the DwarfLab Draco: 15 min from Bortle 6
- Turtle Nebula with the DwarfLab DWARF II: 40 min from Bortle 6
- Turtle Nebula with the Vaonis Vespera II: 12 min from Bortle 6
- Turtle Nebula with the Vaonis Vespera Pro: 27 min from Bortle 6
- Turtle Nebula with the Vaonis Vespera 3: 12 min from Bortle 6
- Turtle Nebula with the Vaonis Vespera Pro 2: 26 min from Bortle 6
- Turtle Nebula with the Unistellar eQuinox 2: 10 min from Bortle 6
- Turtle Nebula with the Celestron Origin: 5 min from Bortle 6
- Turtle Nebula with the Celestron Origin Mark II: 5 min from Bortle 6
All telescopes for the Turtle Nebula · All targets for the Odyssey