How long to image the M99 with the Celestron Origin Mark II
From a Bortle 6 suburban sky, the Celestron Origin Mark II needs about 1 h 01 min (367 subs of 10 s) for a solid image of the M99. A quick look takes 15 min; a showpiece 4 h 04 min. Under a Bortle 3 rural sky the solid figure drops to 19 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 fills 12% 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 | 4 min23 subs | 15 min92 subs | 1 h 01 min367 subs |
| Bortle 2Typical dark site | 4 min26 subs | 17 min101 subs | 1 h 07 min401 subs |
| Bortle 3Rural | 5 min30 subs | 19 min117 subs | 1 h 17 min465 subs |
| Bortle 4Rural / suburban transition | 6 min39 subs | 26 min155 subs | 1 h 43 min620 subs |
| Bortle 5Suburban | 9 min55 subs | 36 min217 subs | 2 h 24 min865 subs |
| Bortle 6Bright suburban | 15 min92 subs | 1 h 01 min367 subs | 4 h 04 min1,466 subs |
| Bortle 7Suburban / urban transition | 27 min164 subs | 1 h 49 min653 subs | 7 h 15 min2,611 subs |
| Bortle 8City | 46 min275 subs | 3 h 03 min1,098 subs | 12 h4,389 subs |
| Bortle 9Inner city | 1 h 25 min512 subs | 5 h 41 min2,046 subs | 23 h8,181 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 1 h 19 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 M99 is 5.4′ × 4.8′ across. The Origin Mark II frames 1.32° × 0.75° at 1.23″ per pixel, so it fills 12% of the frame’s short side.
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 | 19 min117 subs | 36 min217 subs | 1 h 49 min653 subs |
| 15 s | 19 min76 subs | 36 min143 subs | 1 h 48 min434 subs |
| 30 s | 19 min38 subs | 35 min71 subs | 1 h 48 min216 subs |
About the M99
A face-on spiral with one arm flung out by an encounter. Small but distinctive.
NGC 4254, Coma Pinwheel · Galaxy in Coma Berenices · magnitude 9.9 · 5.4′ × 4.8′ · 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 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 M99 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
- M99 with the ZWO Seestar S50: 2 h 48 min from Bortle 6
- M99 with the ZWO Seestar S50 Pro: 3 h 04 min from Bortle 6
- M99 with the ZWO Seestar S30: 2 h 56 min from Bortle 6
- M99 with the ZWO Seestar S30 Pro: 3 h 15 min from Bortle 6
- M99 with the DwarfLab DWARF 3: 4 h 04 min from Bortle 6
- M99 with the DwarfLab DWARF mini: 2 h 47 min from Bortle 6
- M99 with the DwarfLab Draco: 2 h 18 min from Bortle 6
- M99 with the DwarfLab DWARF II: 9 h 34 min from Bortle 6
- M99 with the Vaonis Vespera II: 2 h 48 min from Bortle 6
- M99 with the Vaonis Vespera Pro: 6 h 16 min from Bortle 6
- M99 with the Vaonis Vespera 3: 2 h 40 min from Bortle 6
- M99 with the Vaonis Vespera Pro 2: 5 h 58 min from Bortle 6
- M99 with the Unistellar eQuinox 2: 2 h 32 min from Bortle 6
- M99 with the Unistellar Odyssey: 12 h from Bortle 6
- M99 with the Celestron Origin: 44 min from Bortle 6
All telescopes for the M99 · All targets for the Origin Mark II