How long to image the Cat's Eye Nebula with the Celestron Origin Mark II
From a Bortle 6 suburban sky, the Celestron Origin Mark II needs about 5 min (30 subs of 10 s) for a solid image of the Cat's Eye Nebula. A quick look takes 2 min; a showpiece 18 min. Under a Bortle 3 rural sky the solid figure drops to 5 min. At Bortle 6 the limit is skyglow, so a darker site or a filter helps more than longer subs. In this scope's field it is small in the frame, about 19 pixels across.
| Sky | Quick lookTarget obvious, still noisy | SolidClean enough to share | ShowpieceSmooth faint detail, print-worthy |
|---|---|---|---|
| Bortle 1Excellent dark site | 2 min10 subs | 5 min30 subs | 15 min90 subs |
| Bortle 2Typical dark site | 2 min10 subs | 5 min30 subs | 15 min90 subs |
| Bortle 3Rural | 2 min10 subs | 5 min30 subs | 15 min90 subs |
| Bortle 4Rural / suburban transition | 2 min10 subs | 5 min30 subs | 15 min90 subs |
| Bortle 5Suburban | 2 min10 subs | 5 min30 subs | 15 min90 subs |
| Bortle 6Bright suburban | 2 min10 subs | 5 min30 subs | 18 min111 subs |
| Bortle 7Suburban / urban transition | 2 min11 subs | 7 min44 subs | 29 min176 subs |
| Bortle 8City | 3 min18 subs | 11 min69 subs | 46 min276 subs |
| Bortle 9Inner city | 5 min31 subs | 20 min123 subs | 1 h 21 min489 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 7 min of run time. The Origin Mark II’s battery (rated about 6 h) should cover it; a power bank still keeps the phone running the app alive. (Bortle 6, solid image; we allow 30% over the integration time.)
- portable power station 300W AC outletRuns the supplied 12 V adapter off-grid; dew shield and heater are built in.
- 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 Origin Mark II →
How it frames
The Cat's Eye Nebula is 0.4′ × 0.3′ across. The Origin Mark II frames 1.32° × 0.75° at 1.23″ per pixel, so it is small in the frame, about 19 pixels across. It is worth doing, but the result is a crop rather than a full frame; a longer focal length would resolve more of it.
Longer subs
10 s auto subs (15 s with the Nebula Filter); manual 1 to 30 s on the alt-az mount, longer only with the EQ wedge, and 60 s and up needs the StarSense Autoguider too. Celestron warns the f/2.2 optics saturate quickly without the filter. Time for a solid image by sub length:
| Sub length | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| 10 s | 5 min30 subs | 5 min30 subs | 7 min44 subs |
| 15 s | 8 min30 subs | 8 min30 subs | 8 min30 subs |
| 30 s | 15 min30 subs | 15 min30 subs | 15 min30 subs |
With and without the dual-band filter
| Filter | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| No filter | 5 min30 subs | 5 min30 subs | 7 min44 subs |
| dual-band (Nebula Filter), drawer | 5 min30 subs | 5 min30 subs | 5 min30 subs |
The Origin Mark II has no built-in dual-band filter. Filter drawer takes 1.25-inch or 2-inch filters, including dual-band; Celestron sells an optional Nebula Filter. On an emission target like this it is the single biggest upgrade you can make.
About the Cat's Eye Nebula
A tiny, intensely bright planetary. The core saturates in seconds; the faint outer halo around it is a long dual-band project.
NGC 6543, Caldwell 6 · Planetary nebula in Draco · magnitude 9.0 · 0.4′ × 0.3′ · best in May, Jun, Jul. Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.
Planetary nebulae are small but intensely bright per pixel in OIII and H-alpha, so they respond very well to a dual-band filter and do not need much time for the main shell. The faint outer halos most of them have are a different proposition and need hours. Keep subs short if the central region saturates.
About the Celestron Origin Mark II
The Origin Mark II (late 2025): the same 6-inch f/2.2 RASA with an 8 MP IMX678 in place of the original 6 MP IMX178. Smaller pixels for finer detail, a quieter sensor, and still the fastest system here by a wide margin.
10 s auto subs (15 s with the Nebula Filter); manual 1 to 30 s on the alt-az mount, longer only with the EQ wedge, and 60 s and up needs the StarSense Autoguider too. Celestron warns the f/2.2 optics saturate quickly without the filter. Filter drawer takes 1.25-inch or 2-inch filters, including dual-band; Celestron sells an optional Nebula Filter.
Longer subs matter most under dark skies, where read noise rather than skyglow sets the floor. From a city the difference between 10 s and 30 s subs is small; from a rural site it can halve the total time, especially with a dual-band filter in place.
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 Cat's Eye Nebula from a Origin Mark II? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- Cat's Eye Nebula with the ZWO Seestar S50: 10 min from Bortle 6
- Cat's Eye Nebula with the ZWO Seestar S50 Pro: 11 min from Bortle 6
- Cat's Eye Nebula with the ZWO Seestar S30: 11 min from Bortle 6
- Cat's Eye Nebula with the ZWO Seestar S30 Pro: 12 min from Bortle 6
- Cat's Eye Nebula with the DwarfLab DWARF 3: 14 min from Bortle 6
- Cat's Eye Nebula with the DwarfLab DWARF mini: 10 min from Bortle 6
- Cat's Eye Nebula with the DwarfLab Draco: 15 min from Bortle 6
- Cat's Eye Nebula with the DwarfLab DWARF II: 40 min from Bortle 6
- Cat's Eye Nebula with the Vaonis Vespera II: 12 min from Bortle 6
- Cat's Eye Nebula with the Vaonis Vespera Pro: 27 min from Bortle 6
- Cat's Eye Nebula with the Vaonis Vespera 3: 12 min from Bortle 6
- Cat's Eye Nebula with the Vaonis Vespera Pro 2: 26 min from Bortle 6
- Cat's Eye Nebula with the Unistellar eQuinox 2: 10 min from Bortle 6
- Cat's Eye Nebula with the Unistellar Odyssey: 46 min from Bortle 6
- Cat's Eye Nebula with the Celestron Origin: 5 min from Bortle 6
All telescopes for the Cat's Eye Nebula · All targets for the Origin Mark II