How long to image the Pacman Nebula with the Unistellar Odyssey
From a Bortle 6 suburban sky, the Unistellar Odyssey needs about 11 h (10,297 subs of 4 s) for a solid image of the Pacman Nebula. A quick look takes 2 h 52 min; a showpiece 46 h. Under a Bortle 3 rural sky the solid figure drops to 7 h 36 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 1.0×.
| Sky | Quick lookTarget obvious, still noisy | SolidClean enough to share | ShowpieceSmooth faint detail, print-worthy |
|---|---|---|---|
| Bortle 1Excellent dark site | 1 h 48 min1,627 subs | 7 h 14 min6,507 subs | 29 h26,025 subs |
| Bortle 2Typical dark site | 1 h 50 min1,656 subs | 7 h 21 min6,623 subs | 29 h26,490 subs |
| Bortle 3Rural | 1 h 54 min1,711 subs | 7 h 36 min6,843 subs | 30 h27,371 subs |
| Bortle 4Rural / suburban transition | 2 h 03 min1,845 subs | 8 h 12 min7,377 subs | 33 h29,505 subs |
| Bortle 5Suburban | 2 h 17 min2,056 subs | 9 h 08 min8,222 subs | 37 h32,887 subs |
| Bortle 6Bright suburban | 2 h 52 min2,575 subs | 11 h10,297 subs | 46 h41,186 subs |
| Bortle 7Suburban / urban transition | 3 h 57 min3,563 subs | 16 h14,250 subs | 63 h56,998 subs |
| Bortle 8City | 5 h 40 min5,097 subs | 23 h20,387 subs | 91 h81,548 subs |
| Bortle 9Inner city | 9 h 18 min8,370 subs | 37 h33,477 subs | 150+ h133,907 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 15 h of run time. That is more than one night: over 3 nights, about 4 h 57 min each. The Odyssey’s battery is rated at about 5 h, which is cutting it fine; take a 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 Pacman Nebula is 35′ × 30′ across. The Odyssey frames 0.75° × 0.56° at 0.93″ per pixel, so it is just over the frame at 1.0×. Point at the part you want; the edges will fall outside the frame.
Filters
The Pacman Nebula is an emission target, where a dual-band filter would normally cut the time several-fold from a lit sky, but the Odyssey has no dual-band option: No filter option; Unistellar says third-party filters cannot be fitted to the Odyssey. The figures above are for the No filter position, and a darker sky is the lever that remains.
About the Pacman Nebula
A bright emission nebula with a dark lane biting into it. Compact, bright, and excellent with a dual-band filter from suburban skies.
NGC 281 · Emission nebula in Cassiopeia · magnitude 7.4 · 35′ × 30′ · best in Sep, Oct, Nov. Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.
Emission nebulae glow in a few narrow lines, mostly hydrogen-alpha (deep red) and doubly ionised oxygen (teal). A dual-band filter passes those lines and blocks most skyglow, which is why it cuts the time needed from a suburban sky so dramatically. Use it. From a genuinely dark site the gain is smaller because there is less skyglow to block, and read noise becomes the limit, which is where longer subs (EQ mode, or Expert Mode on a Vespera) earn their keep.
Stars lose colour through a dual-band filter; a short broadband stack blended in fixes that if you care.
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 Pacman Nebula from a Odyssey? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- Pacman Nebula with the ZWO Seestar S50: 1 h 41 min from Bortle 6
- Pacman Nebula with the ZWO Seestar S50 Pro: 1 h 53 min from Bortle 6
- Pacman Nebula with the ZWO Seestar S30: 1 h 58 min from Bortle 6
- Pacman Nebula with the ZWO Seestar S30 Pro: 2 h 02 min from Bortle 6
- Pacman Nebula with the DwarfLab DWARF 3: 2 h 05 min from Bortle 6
- Pacman Nebula with the DwarfLab DWARF mini: 1 h 40 min from Bortle 6
- Pacman Nebula with the DwarfLab Draco: 1 h 20 min from Bortle 6
- Pacman Nebula with the DwarfLab DWARF II: 9 h 16 min from Bortle 6
- Pacman Nebula with the Vaonis Vespera II: 2 h 42 min from Bortle 6
- Pacman Nebula with the Vaonis Vespera Pro: 6 h 03 min from Bortle 6
- Pacman Nebula with the Vaonis Vespera 3: 2 h 35 min from Bortle 6
- Pacman Nebula with the Vaonis Vespera Pro 2: 5 h 46 min from Bortle 6
- Pacman Nebula with the Unistellar eQuinox 2: 2 h 28 min from Bortle 6
- Pacman Nebula with the Celestron Origin: 43 min from Bortle 6
- Pacman Nebula with the Celestron Origin Mark II: 59 min from Bortle 6
All telescopes for the Pacman Nebula · All targets for the Odyssey