How long to image the M49 with the Unistellar Odyssey

From a Bortle 6 suburban sky, the Unistellar Odyssey needs about 4 h 46 min (4,284 subs of 4 s) for a solid image of the M49. A quick look takes 1 h 11 min; a showpiece 19 h. Under a Bortle 3 rural sky the solid figure drops to 3 h 13 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it fills 30% of the frame’s short side.

M49 with the Unistellar Odyssey: 4 s subs.
SkyQuick lookTarget obvious, still noisySolidClean enough to shareShowpieceSmooth faint detail, print-worthy
Bortle 1Excellent dark site46 min690 subs3 h 04 min2,757 subs12 h11,026 subs
Bortle 2Typical dark site47 min701 subs3 h 07 min2,804 subs12 h11,214 subs
Bortle 3Rural48 min724 subs3 h 13 min2,893 subs13 h11,569 subs
Bortle 4Rural / suburban transition52 min777 subs3 h 27 min3,107 subs14 h12,428 subs
Bortle 5Suburban57 min862 subs3 h 50 min3,448 subs15 h13,790 subs
Bortle 6Bright suburban1 h 11 min1,071 subs4 h 46 min4,284 subs19 h17,133 subs
Bortle 7Suburban / urban transition1 h 38 min1,469 subs6 h 32 min5,876 subs26 h23,501 subs
Bortle 8City2 h 19 min2,087 subs9 h 16 min8,348 subs37 h33,389 subs
Bortle 9Inner city3 h 47 min3,405 subs15 h13,620 subs61 h54,478 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 6 h 11 min of run time. The Odyssey’s battery is rated at about 5 h, so the session needs an external power bank. (Bortle 6, solid image; we allow 30% over the integration time.)

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How it frames

The M49 is 10′ × 8′ across. The Odyssey frames 0.75° × 0.56° at 0.93″ per pixel, so it fills 30% of the frame’s short side.

About the M49

The brightest galaxy in the Virgo cluster, a featureless elliptical. Comes quickly but shows no structure.

NGC 4472 · Galaxy in Virgo · magnitude 8.4 · 10′ × 8′ · best in Mar, Apr, May. 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 M49 with your Odyssey? Did the solid figure match?Anonymous, one tap. It is how the model gets calibrated.

Have an image of the M49 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 M49 · All targets for the Odyssey