How long to image the Ghost of Cassiopeia with the Unistellar Odyssey
From a Bortle 6 suburban sky, the Unistellar Odyssey needs about 12 h (10,762 subs of 4 s) for a solid image of the Ghost of Cassiopeia. A quick look takes 2 h 59 min; a showpiece 48 h. Under a Bortle 3 rural sky the solid figure drops to 7 h 58 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.
| Sky | Quick lookTarget obvious, still noisy | SolidClean enough to share | ShowpieceSmooth faint detail, print-worthy |
|---|---|---|---|
| Bortle 1Excellent dark site | 1 h 54 min1,707 subs | 7 h 35 min6,828 subs | 30 h27,312 subs |
| Bortle 2Typical dark site | 1 h 56 min1,738 subs | 7 h 43 min6,949 subs | 31 h27,795 subs |
| Bortle 3Rural | 2 h1,795 subs | 7 h 58 min7,178 subs | 32 h28,709 subs |
| Bortle 4Rural / suburban transition | 2 h 09 min1,933 subs | 8 h 35 min7,731 subs | 34 h30,924 subs |
| Bortle 5Suburban | 2 h 23 min2,153 subs | 9 h 34 min8,609 subs | 38 h34,434 subs |
| Bortle 6Bright suburban | 2 h 59 min2,691 subs | 12 h10,762 subs | 48 h43,045 subs |
| Bortle 7Suburban / urban transition | 4 h 08 min3,716 subs | 17 h14,864 subs | 66 h59,454 subs |
| Bortle 8City | 5 h 54 min5,309 subs | 24 h21,233 subs | 94 h84,931 subs |
| Bortle 9Inner city | 9 h 40 min8,705 subs | 39 h34,817 subs | 150+ h139,266 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 16 h of run time. That is more than one night: over 3 nights, about 5 h 11 min each. The Odyssey’s battery is rated at about 5 h, so each night 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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How it frames
The Ghost of Cassiopeia is 10′ × 3′ across. The Odyssey frames 0.75° × 0.56° at 0.93″ per pixel, so it fills 30% of the frame’s short side.
Filters
The Ghost of Cassiopeia 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 Ghost of Cassiopeia
A small emission and reflection wisp being eroded by the star Gamma Cassiopeiae. Keep the bright star's glare under control.
IC 63 · Emission nebula in Cassiopeia · magnitude 10.0 · 10′ × 3′ · 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 Ghost of Cassiopeia from a Odyssey? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- Ghost of Cassiopeia with the ZWO Seestar S50: 1 h 48 min from Bortle 6
- Ghost of Cassiopeia with the ZWO Seestar S50 Pro: 2 h 01 min from Bortle 6
- Ghost of Cassiopeia with the ZWO Seestar S30: 2 h 06 min from Bortle 6
- Ghost of Cassiopeia with the ZWO Seestar S30 Pro: 2 h 11 min from Bortle 6
- Ghost of Cassiopeia with the DwarfLab DWARF 3: 2 h 15 min from Bortle 6
- Ghost of Cassiopeia with the DwarfLab DWARF mini: 1 h 46 min from Bortle 6
- Ghost of Cassiopeia with the DwarfLab Draco: 1 h 26 min from Bortle 6
- Ghost of Cassiopeia with the DwarfLab DWARF II: 9 h 43 min from Bortle 6
- Ghost of Cassiopeia with the Vaonis Vespera II: 2 h 50 min from Bortle 6
- Ghost of Cassiopeia with the Vaonis Vespera Pro: 6 h 21 min from Bortle 6
- Ghost of Cassiopeia with the Vaonis Vespera 3: 2 h 43 min from Bortle 6
- Ghost of Cassiopeia with the Vaonis Vespera Pro 2: 6 h 03 min from Bortle 6
- Ghost of Cassiopeia with the Unistellar eQuinox 2: 2 h 35 min from Bortle 6
- Ghost of Cassiopeia with the Celestron Origin: 45 min from Bortle 6
- Ghost of Cassiopeia with the Celestron Origin Mark II: 1 h 02 min from Bortle 6
All telescopes for the Ghost of Cassiopeia · All targets for the Odyssey