How long to image the De Mairan's Nebula with the Unistellar Odyssey
From a Bortle 6 suburban sky, the Unistellar Odyssey needs about 3 h 15 min (2,927 subs of 4 s) for a solid image of the De Mairan's Nebula. A quick look takes 49 min; a showpiece 13 h. Under a Bortle 3 rural sky the solid figure drops to 2 h 12 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it fills 59% 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 | 31 min471 subs | 2 h 05 min1,883 subs | 8 h 22 min7,530 subs |
| Bortle 2Typical dark site | 32 min479 subs | 2 h 08 min1,915 subs | 8 h 31 min7,659 subs |
| Bortle 3Rural | 33 min494 subs | 2 h 12 min1,976 subs | 8 h 47 min7,901 subs |
| Bortle 4Rural / suburban transition | 35 min531 subs | 2 h 21 min2,123 subs | 9 h 26 min8,489 subs |
| Bortle 5Suburban | 39 min589 subs | 2 h 37 min2,356 subs | 10 h9,421 subs |
| Bortle 6Bright suburban | 49 min732 subs | 3 h 15 min2,927 subs | 13 h11,706 subs |
| Bortle 7Suburban / urban transition | 1 h 07 min1,004 subs | 4 h 28 min4,016 subs | 18 h16,061 subs |
| Bortle 8City | 1 h 35 min1,427 subs | 6 h 20 min5,706 subs | 25 h22,823 subs |
| Bortle 9Inner city | 2 h 35 min2,328 subs | 10 h9,311 subs | 41 h37,244 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 4 h 14 min of run time. The Odyssey’s battery is rated at about 5 h, less near freezing, so the session needs an external power bank. (Bortle 6, solid image; we allow 30% over the integration time, and 30% off the battery for a December 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 De Mairan's Nebula is 20′ × 15′ across. The Odyssey frames 0.75° × 0.56° at 0.93″ per pixel, so it fills 59% of the frame’s short side.
Filters
The De Mairan's 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 De Mairan's Nebula
The comma-shaped nebula north of the Orion Nebula's core, split from it by a dark lane. Always in the same frame as M42.
M43, NGC 1982 · Emission nebula in Orion · magnitude 9.0 · 20′ × 15′ · best in Nov, Dec, Jan. 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 De Mairan's Nebula from a Odyssey? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- De Mairan's Nebula with the ZWO Seestar S50: 32 min from Bortle 6
- De Mairan's Nebula with the ZWO Seestar S50 Pro: 35 min from Bortle 6
- De Mairan's Nebula with the ZWO Seestar S30: 36 min from Bortle 6
- De Mairan's Nebula with the ZWO Seestar S30 Pro: 38 min from Bortle 6
- De Mairan's Nebula with the DwarfLab DWARF 3: 40 min from Bortle 6
- De Mairan's Nebula with the DwarfLab DWARF mini: 31 min from Bortle 6
- De Mairan's Nebula with the DwarfLab Draco: 25 min from Bortle 6
- De Mairan's Nebula with the DwarfLab DWARF II: 2 h 41 min from Bortle 6
- De Mairan's Nebula with the Vaonis Vespera II: 47 min from Bortle 6
- De Mairan's Nebula with the Vaonis Vespera Pro: 1 h 46 min from Bortle 6
- De Mairan's Nebula with the Vaonis Vespera 3: 45 min from Bortle 6
- De Mairan's Nebula with the Vaonis Vespera Pro 2: 1 h 41 min from Bortle 6
- De Mairan's Nebula with the Unistellar eQuinox 2: 42 min from Bortle 6
- De Mairan's Nebula with the Celestron Origin: 13 min from Bortle 6
- De Mairan's Nebula with the Celestron Origin Mark II: 17 min from Bortle 6
All telescopes for the De Mairan's Nebula · All targets for the Odyssey