How long to image the M4 with the Unistellar Odyssey
From a Bortle 6 suburban sky, the Unistellar Odyssey needs about 5 h 11 min (4,659 subs of 4 s) for a solid image of the M4. A quick look takes 1 h 18 min; a showpiece 21 h. Under a Bortle 3 rural sky the solid figure drops to 3 h 28 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it is just over the frame at 1.1×.
| Sky | Quick lookTarget obvious, still noisy | SolidClean enough to share | ShowpieceSmooth faint detail, print-worthy |
|---|---|---|---|
| Bortle 1Excellent dark site | 50 min744 subs | 3 h 18 min2,974 subs | 13 h11,894 subs |
| Bortle 2Typical dark site | 50 min757 subs | 3 h 22 min3,026 subs | 13 h12,101 subs |
| Bortle 3Rural | 52 min781 subs | 3 h 28 min3,124 subs | 14 h12,493 subs |
| Bortle 4Rural / suburban transition | 56 min841 subs | 3 h 44 min3,361 subs | 15 h13,442 subs |
| Bortle 5Suburban | 1 h 02 min935 subs | 4 h 09 min3,737 subs | 17 h14,946 subs |
| Bortle 6Bright suburban | 1 h 18 min1,165 subs | 5 h 11 min4,659 subs | 21 h18,635 subs |
| Bortle 7Suburban / urban transition | 1 h 47 min1,605 subs | 7 h 08 min6,417 subs | 29 h25,666 subs |
| Bortle 8City | 2 h 32 min2,287 subs | 10 h9,146 subs | 41 h36,581 subs |
| Bortle 9Inner city | 4 h 09 min3,742 subs | 17 h14,966 subs | 67 h59,861 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 6 h 44 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 M4 is 36′ across. The Odyssey frames 0.75° × 0.56° at 0.93″ per pixel, so it is just over the frame at 1.1×. Point at the part you want; the edges will fall outside the frame.
About the M4
The loose globular next to Antares. Low in the sky from the UK, so image it near transit.
NGC 6121 · Globular cluster in Scorpius · magnitude 5.9 · 36′ · best in May, Jun, Jul. 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 M4 from a Odyssey? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- M4 with the ZWO Seestar S50: 1 h 14 min from Bortle 6
- M4 with the ZWO Seestar S50 Pro: 1 h 21 min from Bortle 6
- M4 with the ZWO Seestar S30: 1 h 18 min from Bortle 6
- M4 with the ZWO Seestar S30 Pro: 1 h 26 min from Bortle 6
- M4 with the DwarfLab DWARF 3: 1 h 48 min from Bortle 6
- M4 with the DwarfLab DWARF mini: 1 h 14 min from Bortle 6
- M4 with the DwarfLab Draco: 1 h 01 min from Bortle 6
- M4 with the DwarfLab DWARF II: 4 h 14 min from Bortle 6
- M4 with the Vaonis Vespera II: 1 h 14 min from Bortle 6
- M4 with the Vaonis Vespera Pro: 2 h 46 min from Bortle 6
- M4 with the Vaonis Vespera 3: 1 h 11 min from Bortle 6
- M4 with the Vaonis Vespera Pro 2: 2 h 39 min from Bortle 6
- M4 with the Unistellar eQuinox 2: 1 h 07 min from Bortle 6
- M4 with the Celestron Origin: 20 min from Bortle 6
- M4 with the Celestron Origin Mark II: 27 min from Bortle 6