How long to image the Thor's Helmet with the Unistellar Odyssey
From a Bortle 6 suburban sky, the Unistellar Odyssey needs about 44 h (39,897 subs of 4 s) for a solid image of the Thor's Helmet. A quick look takes 11 h; a showpiece 180+ h. Under a Bortle 3 rural sky the solid figure drops to 29 h. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it fills 24% 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 | 6 h 57 min6,263 subs | 28 h25,049 subs | 110+ h100,196 subs |
| Bortle 2Typical dark site | 7 h 05 min6,377 subs | 28 h25,505 subs | 110+ h102,020 subs |
| Bortle 3Rural | 7 h 19 min6,592 subs | 29 h26,368 subs | 120+ h105,470 subs |
| Bortle 4Rural / suburban transition | 7 h 54 min7,115 subs | 32 h28,458 subs | 130+ h113,830 subs |
| Bortle 5Suburban | 8 h 49 min7,943 subs | 35 h31,770 subs | 140+ h127,079 subs |
| Bortle 6Bright suburban | 11 h9,975 subs | 44 h39,897 subs | 180+ h159,587 subs |
| Bortle 7Suburban / urban transition | 15 h13,846 subs | 62 h55,383 subs | 250+ h221,530 subs |
| Bortle 8City | 22 h19,857 subs | 88 h79,426 subs | 350+ h317,704 subs |
| Bortle 9Inner city | 36 h32,676 subs | 150+ h130,704 subs | 580+ h522,815 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 58 h of run time. That is more than one night: over 9 nights, about 6 h 24 min each. The Odyssey’s battery is rated at about 5 h, less near freezing, so each night needs an external power bank. (Bortle 6, solid image; we allow 30% over the integration time, and 30% off the battery for a January night.)
- 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.
- hand warmers long lastingAir-activated packs give hours of heat for the person; winter nights are long and you spend most of them standing still.
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Everything that fits the Odyssey →
How it frames
The Thor's Helmet is 8′ across. The Odyssey frames 0.75° × 0.56° at 0.93″ per pixel, so it fills 24% of the frame’s short side.
Filters
The Thor's Helmet 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 Thor's Helmet
A Wolf-Rayet bubble with wings, strong in OIII. Small and faint; dual-band is essential and a bigger scope helps.
NGC 2359 · Emission nebula in Canis Major · magnitude 11.5 · 8′ · best in Dec, Jan, Feb. Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.
Emission nebulae glow in a few narrow lines, mostly hydrogen-alpha (deep red) and doubly ionised oxygen (teal). A dual-band filter passes those lines and blocks most skyglow, which is why it cuts the time needed from a suburban sky so dramatically. Use it. From a genuinely dark site the gain is smaller because there is less skyglow to block, and read noise becomes the limit, which is where longer subs (EQ mode, or Expert Mode on a Vespera) earn their keep.
Stars lose colour through a dual-band filter; a short broadband stack blended in fixes that if you care.
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 Thor's Helmet from a Odyssey? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- Thor's Helmet with the ZWO Seestar S50: 6 h 17 min from Bortle 6
- Thor's Helmet with the ZWO Seestar S50 Pro: 7 h 04 min from Bortle 6
- Thor's Helmet with the ZWO Seestar S30: 7 h 24 min from Bortle 6
- Thor's Helmet with the ZWO Seestar S30 Pro: 7 h 38 min from Bortle 6
- Thor's Helmet with the DwarfLab DWARF 3: 7 h 41 min from Bortle 6
- Thor's Helmet with the DwarfLab DWARF mini: 6 h 11 min from Bortle 6
- Thor's Helmet with the DwarfLab Draco: 4 h 58 min from Bortle 6
- Thor's Helmet with the DwarfLab DWARF II: 36 h from Bortle 6
- Thor's Helmet with the Vaonis Vespera II: 10 h from Bortle 6
- Thor's Helmet with the Vaonis Vespera Pro: 23 h from Bortle 6
- Thor's Helmet with the Vaonis Vespera 3: 9 h 53 min from Bortle 6
- Thor's Helmet with the Vaonis Vespera Pro 2: 22 h from Bortle 6
- Thor's Helmet with the Unistellar eQuinox 2: 9 h 31 min from Bortle 6
- Thor's Helmet with the Celestron Origin: 2 h 44 min from Bortle 6
- Thor's Helmet with the Celestron Origin Mark II: 3 h 44 min from Bortle 6
All telescopes for the Thor's Helmet · All targets for the Odyssey