How long to image the Sculptor Galaxy with the Unistellar Odyssey

From a Bortle 6 suburban sky, the Unistellar Odyssey needs about 1 h 59 min (1,780 subs of 4 s) for a solid image of the Sculptor Galaxy. A quick look takes 30 min; a showpiece 7 h 55 min. Under a Bortle 3 rural sky the solid figure drops to 1 h 21 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it fills 80% of the frame’s short side.

Sculptor Galaxy with the Unistellar Odyssey: 4 s subs.
SkyQuick lookTarget obvious, still noisySolidClean enough to shareShowpieceSmooth faint detail, print-worthy
Bortle 1Excellent dark site19 min290 subs1 h 17 min1,157 subs5 h 08 min4,627 subs
Bortle 2Typical dark site20 min294 subs1 h 18 min1,176 subs5 h 14 min4,704 subs
Bortle 3Rural20 min303 subs1 h 21 min1,212 subs5 h 23 min4,848 subs
Bortle 4Rural / suburban transition22 min325 subs1 h 27 min1,300 subs5 h 47 min5,199 subs
Bortle 5Suburban24 min360 subs1 h 36 min1,439 subs6 h 24 min5,755 subs
Bortle 6Bright suburban30 min445 subs1 h 59 min1,780 subs7 h 55 min7,118 subs
Bortle 7Suburban / urban transition40 min608 subs2 h 42 min2,430 subs11 h9,717 subs
Bortle 8City57 min860 subs3 h 49 min3,438 subs15 h13,751 subs
Bortle 9Inner city1 h 33 min1,398 subs6 h 13 min5,589 subs25 h22,355 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 2 h 34 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.)

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Everything that fits the Odyssey →

How it frames

The Sculptor Galaxy is 27′ × 7′ across. The Odyssey frames 0.75° × 0.56° at 0.93″ per pixel, so it fills 80% of the frame’s short side.

About the Sculptor Galaxy

A big, dusty, nearly edge-on starburst galaxy, superb from the south and low but possible from mid-northern latitudes.

NGC 253, Caldwell 65, Silver Coin · Galaxy in Sculptor · magnitude 7.2 · 27′ × 7′ · best in Sep, Oct, Nov. Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.

Galaxies are broadband targets: their light is mostly starlight spread across the spectrum, so a dual-band filter throws most of it away and makes things slower, not faster. Shoot without a filter (or with a plain UV/IR cut) and rely on total time and a dark sky. The core of a galaxy is usually many times brighter than its outer disc, so a short stack shows the nucleus long before the arms; the figures here are for the arms and disc, not the core.

Field rotation in Alt-Az mode crops the edges of the stack over a long session, so on a big galaxy re-centre now and then or use EQ mode where your scope supports it.

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

Have an image of the Sculptor Galaxy 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 Sculptor Galaxy · All targets for the Odyssey