How long to image the Whirlpool Galaxy with the Unistellar Odyssey
From a Bortle 6 suburban sky, the Unistellar Odyssey needs about 4 h 01 min (3,617 subs of 4 s) for a solid image of the Whirlpool Galaxy. A quick look takes 1 h; a showpiece 16 h. Under a Bortle 3 rural sky the solid figure drops to 2 h 43 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it fills 33% 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 | 39 min583 subs | 2 h 35 min2,331 subs | 10 h9,323 subs |
| Bortle 2Typical dark site | 40 min593 subs | 2 h 38 min2,371 subs | 11 h9,481 subs |
| Bortle 3Rural | 41 min612 subs | 2 h 43 min2,445 subs | 11 h9,780 subs |
| Bortle 4Rural / suburban transition | 44 min657 subs | 2 h 55 min2,626 subs | 12 h10,504 subs |
| Bortle 5Suburban | 49 min729 subs | 3 h 14 min2,913 subs | 13 h11,651 subs |
| Bortle 6Bright suburban | 1 h905 subs | 4 h 01 min3,617 subs | 16 h14,466 subs |
| Bortle 7Suburban / urban transition | 1 h 23 min1,240 subs | 5 h 30 min4,958 subs | 22 h19,830 subs |
| Bortle 8City | 1 h 57 min1,760 subs | 7 h 49 min7,040 subs | 31 h28,157 subs |
| Bortle 9Inner city | 3 h 11 min2,870 subs | 13 h11,480 subs | 51 h45,918 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 5 h 13 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 Whirlpool Galaxy is 11′ × 7′ across. The Odyssey frames 0.75° × 0.56° at 0.93″ per pixel, so it fills 33% of the frame’s short side.
About the Whirlpool Galaxy
The classic face-on spiral with its companion tugging at one arm. Small in a smart scope but bright; the arms appear within an hour, the tidal bridge needs several.
M51, NGC 5194 · Galaxy in Canes Venatici · magnitude 8.4 · 11′ × 7′ · 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.
Have an image of the Whirlpool Galaxy from a Odyssey? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- Whirlpool Galaxy with the ZWO Seestar S50: 59 min from Bortle 6
- Whirlpool Galaxy with the ZWO Seestar S50 Pro: 1 h 04 min from Bortle 6
- Whirlpool Galaxy with the ZWO Seestar S30: 1 h 01 min from Bortle 6
- Whirlpool Galaxy with the ZWO Seestar S30 Pro: 1 h 08 min from Bortle 6
- Whirlpool Galaxy with the DwarfLab DWARF 3: 1 h 25 min from Bortle 6
- Whirlpool Galaxy with the DwarfLab DWARF mini: 58 min from Bortle 6
- Whirlpool Galaxy with the DwarfLab Draco: 48 min from Bortle 6
- Whirlpool Galaxy with the DwarfLab DWARF II: 3 h 19 min from Bortle 6
- Whirlpool Galaxy with the Vaonis Vespera II: 59 min from Bortle 6
- Whirlpool Galaxy with the Vaonis Vespera Pro: 2 h 11 min from Bortle 6
- Whirlpool Galaxy with the Vaonis Vespera 3: 56 min from Bortle 6
- Whirlpool Galaxy with the Vaonis Vespera Pro 2: 2 h 05 min from Bortle 6
- Whirlpool Galaxy with the Unistellar eQuinox 2: 52 min from Bortle 6
- Whirlpool Galaxy with the Celestron Origin: 16 min from Bortle 6
- Whirlpool Galaxy with the Celestron Origin Mark II: 21 min from Bortle 6
All telescopes for the Whirlpool Galaxy · All targets for the Odyssey