How long to image the Rosette Nebula with the Celestron Origin Mark II
From a Bortle 6 suburban sky, the Celestron Origin Mark II needs about 49 min (295 subs of 10 s) for a solid image of the Rosette Nebula. A quick look takes 12 min; a showpiece 3 h 16 min. Under a Bortle 3 rural sky the solid figure drops to 15 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 1.8× wider than the frame.
| Sky | Quick lookTarget obvious, still noisy | SolidClean enough to share | ShowpieceSmooth faint detail, print-worthy |
|---|---|---|---|
| Bortle 1Excellent dark site | 3 min17 subs | 11 min68 subs | 45 min269 subs |
| Bortle 2Typical dark site | 3 min19 subs | 12 min75 subs | 49 min297 subs |
| Bortle 3Rural | 4 min22 subs | 15 min88 subs | 58 min350 subs |
| Bortle 4Rural / suburban transition | 5 min30 subs | 20 min120 subs | 1 h 20 min478 subs |
| Bortle 5Suburban | 7 min43 subs | 28 min171 subs | 1 h 53 min681 subs |
| Bortle 6Bright suburban | 12 min74 subs | 49 min295 subs | 3 h 16 min1,178 subs |
| Bortle 7Suburban / urban transition | 22 min133 subs | 1 h 29 min532 subs | 5 h 54 min2,126 subs |
| Bortle 8City | 37 min225 subs | 2 h 30 min900 subs | 9 h 59 min3,597 subs |
| Bortle 9Inner city | 1 h 10 min421 subs | 4 h 41 min1,684 subs | 19 h6,735 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 1 h 04 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, and 30% off the battery for a January night.)
- 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.
- hand warmers long lastingAir-activated packs give hours of heat for the person; winter nights are long and you spend most of them standing still.
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Everything that fits the Origin Mark II →
How it frames
The Rosette Nebula is 80′ × 60′ across. The Origin Mark II frames 1.32° × 0.75° at 1.23″ per pixel, so it is 1.8× wider than the frame. A mosaic, or choosing the part you want and letting the rest go, is how it gets shot on this scope.
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 | 15 min88 subs | 28 min171 subs | 1 h 29 min532 subs |
| 15 s | 14 min57 subs | 28 min113 subs | 1 h 28 min353 subs |
| 30 s | 15 min30 subs | 28 min56 subs | 1 h 28 min176 subs |
With and without the dual-band filter
| Filter | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| No filter | 15 min88 subs | 28 min171 subs | 1 h 29 min532 subs |
| dual-band (Nebula Filter), drawer | 11 min69 subs | 16 min95 subs | 34 min205 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 Rosette Nebula
A ring of hydrogen more than a degree across around the cluster NGC 2244. One of the best dual-band targets of winter and forgiving of light pollution.
NGC 2237, NGC 2244, Caldwell 49 · Emission nebula in Monoceros · magnitude 9.0 · 80′ × 60′ · best in Dec, Jan, Feb. 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 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 Rosette 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
- Rosette Nebula with the ZWO Seestar S50: 1 h 25 min from Bortle 6
- Rosette Nebula with the ZWO Seestar S50 Pro: 1 h 36 min from Bortle 6
- Rosette Nebula with the ZWO Seestar S30: 1 h 39 min from Bortle 6
- Rosette Nebula with the ZWO Seestar S30 Pro: 1 h 43 min from Bortle 6
- Rosette Nebula with the DwarfLab DWARF 3: 1 h 46 min from Bortle 6
- Rosette Nebula with the DwarfLab DWARF mini: 1 h 24 min from Bortle 6
- Rosette Nebula with the DwarfLab Draco: 1 h 08 min from Bortle 6
- Rosette Nebula with the DwarfLab DWARF II: 7 h 45 min from Bortle 6
- Rosette Nebula with the Vaonis Vespera II: 2 h 15 min from Bortle 6
- Rosette Nebula with the Vaonis Vespera Pro: 5 h 04 min from Bortle 6
- Rosette Nebula with the Vaonis Vespera 3: 2 h 09 min from Bortle 6
- Rosette Nebula with the Vaonis Vespera Pro 2: 4 h 49 min from Bortle 6
- Rosette Nebula with the Unistellar eQuinox 2: 2 h 04 min from Bortle 6
- Rosette Nebula with the Unistellar Odyssey: 9 h 33 min from Bortle 6
- Rosette Nebula with the Celestron Origin: 36 min from Bortle 6
All telescopes for the Rosette Nebula · All targets for the Origin Mark II