How long to image the M72 with the Unistellar Odyssey
From a Bortle 6 suburban sky, the Unistellar Odyssey needs about 4 h 51 min (4,371 subs of 4 s) for a solid image of the M72. A quick look takes 1 h 13 min; a showpiece 19 h. Under a Bortle 3 rural sky the solid figure drops to 3 h 18 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it fills 18% 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 | 47 min709 subs | 3 h 09 min2,836 subs | 13 h11,342 subs |
| Bortle 2Typical dark site | 48 min721 subs | 3 h 12 min2,883 subs | 13 h11,530 subs |
| Bortle 3Rural | 50 min743 subs | 3 h 18 min2,972 subs | 13 h11,887 subs |
| Bortle 4Rural / suburban transition | 53 min797 subs | 3 h 33 min3,188 subs | 14 h12,752 subs |
| Bortle 5Suburban | 59 min883 subs | 3 h 55 min3,531 subs | 16 h14,122 subs |
| Bortle 6Bright suburban | 1 h 13 min1,093 subs | 4 h 51 min4,371 subs | 19 h17,483 subs |
| Bortle 7Suburban / urban transition | 1 h 40 min1,494 subs | 6 h 38 min5,973 subs | 27 h23,889 subs |
| Bortle 8City | 2 h 21 min2,115 subs | 9 h 24 min8,459 subs | 38 h33,835 subs |
| Bortle 9Inner city | 3 h 49 min3,441 subs | 15 h13,762 subs | 61 h55,045 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 6 h 19 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.)
- 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.
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Everything that fits the Odyssey →
How it frames
The M72 is 6′ across. The Odyssey frames 0.75° × 0.56° at 0.93″ per pixel, so it fills 18% of the frame’s short side.
About the M72
A faint, distant globular in Aquarius. Among the harder Messier globulars.
NGC 6981 · Globular cluster in Aquarius · magnitude 9.3 · 6′ · best in Jul, Aug, Sep. Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.
Globular clusters are point sources packed tight, so they come quickly: the core resolves into stars within a handful of minutes on any smart scope. More time deepens the halo and pulls in the faint outer members. Use short subs so the core does not saturate into a white blob, and no filter.
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 M72 from a Odyssey? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- M72 with the ZWO Seestar S50: 1 h 11 min from Bortle 6
- M72 with the ZWO Seestar S50 Pro: 1 h 18 min from Bortle 6
- M72 with the ZWO Seestar S30: 1 h 15 min from Bortle 6
- M72 with the ZWO Seestar S30 Pro: 1 h 23 min from Bortle 6
- M72 with the DwarfLab DWARF 3: 1 h 44 min from Bortle 6
- M72 with the DwarfLab DWARF mini: 1 h 11 min from Bortle 6
- M72 with the DwarfLab Draco: 59 min from Bortle 6
- M72 with the DwarfLab DWARF II: 4 h 02 min from Bortle 6
- M72 with the Vaonis Vespera II: 1 h 11 min from Bortle 6
- M72 with the Vaonis Vespera Pro: 2 h 39 min from Bortle 6
- M72 with the Vaonis Vespera 3: 1 h 08 min from Bortle 6
- M72 with the Vaonis Vespera Pro 2: 2 h 32 min from Bortle 6
- M72 with the Unistellar eQuinox 2: 1 h 04 min from Bortle 6
- M72 with the Celestron Origin: 19 min from Bortle 6
- M72 with the Celestron Origin Mark II: 26 min from Bortle 6