How long to image the Orion Nebula with the Unistellar Odyssey

From a Bortle 6 suburban sky, the Unistellar Odyssey needs about 1 h 08 min (1,016 subs of 4 s) for a solid image of the Orion Nebula. A quick look takes 17 min; a showpiece 4 h 31 min. Under a Bortle 3 rural sky the solid figure drops to 47 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it is 2.5× wider than the frame.

Orion Nebula with the Unistellar Odyssey: 4 s subs.
SkyQuick lookTarget obvious, still noisySolidClean enough to shareShowpieceSmooth faint detail, print-worthy
Bortle 1Excellent dark site11 min168 subs45 min670 subs2 h 59 min2,680 subs
Bortle 2Typical dark site11 min171 subs45 min681 subs3 h 01 min2,723 subs
Bortle 3Rural12 min176 subs47 min701 subs3 h 07 min2,803 subs
Bortle 4Rural / suburban transition12 min188 subs50 min750 subs3 h 20 min2,998 subs
Bortle 5Suburban14 min207 subs55 min827 subs3 h 40 min3,306 subs
Bortle 6Bright suburban17 min254 subs1 h 08 min1,016 subs4 h 31 min4,063 subs
Bortle 7Suburban / urban transition23 min345 subs1 h 32 min1,377 subs6 h 07 min5,505 subs
Bortle 8City32 min484 subs2 h 09 min1,936 subs8 h 36 min7,744 subs
Bortle 9Inner city52 min783 subs3 h 29 min3,130 subs14 h12,519 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 1 h 28 min 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, and 30% off the battery for a December night.)

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How it frames

The Orion Nebula is 85′ × 60′ across. The Odyssey frames 0.75° × 0.56° at 0.93″ per pixel, so it is 2.5× wider than the frame. A mosaic, or choosing the part you want and letting the rest go, is how it gets shot on this scope.

Filters

The Orion 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 Orion Nebula

The brightest nebula in the northern sky and the one every smart scope gets pointed at first. The core saturates in a minute; the wings and the Running Man need real time. Mix short and long stacks.

M42, NGC 1976 · Emission nebula in Orion · magnitude 4.0 · 85′ × 60′ · 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.

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Imaged the Orion Nebula with your Odyssey? Did the solid figure match?Anonymous, one tap. It is how the model gets calibrated.

Have an image of the Orion Nebula from a Odyssey? Email it with your total time and sky to [email protected] and it goes here, credited.

Same target, other telescopes

All telescopes for the Orion Nebula · All targets for the Odyssey