How long to image the M61 with the Celestron Origin Mark II
From a Bortle 6 suburban sky, the Celestron Origin Mark II needs about 1 h 08 min (409 subs of 10 s) for a solid image of the M61. A quick look takes 17 min; a showpiece 4 h 32 min. Under a Bortle 3 rural sky the solid figure drops to 21 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 13% 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 min26 subs | 17 min101 subs | 1 h 07 min402 subs |
| Bortle 2Typical dark site | 5 min28 subs | 18 min110 subs | 1 h 13 min440 subs |
| Bortle 3Rural | 5 min32 subs | 21 min128 subs | 1 h 25 min512 subs |
| Bortle 4Rural / suburban transition | 7 min43 subs | 29 min172 subs | 1 h 54 min685 subs |
| Bortle 5Suburban | 10 min60 subs | 40 min240 subs | 2 h 40 min960 subs |
| Bortle 6Bright suburban | 17 min103 subs | 1 h 08 min409 subs | 4 h 32 min1,634 subs |
| Bortle 7Suburban / urban transition | 30 min183 subs | 2 h 02 min730 subs | 8 h 06 min2,918 subs |
| Bortle 8City | 51 min307 subs | 3 h 25 min1,228 subs | 14 h4,912 subs |
| Bortle 9Inner city | 1 h 35 min573 subs | 6 h 22 min2,291 subs | 25 h9,164 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 1 h 28 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 M61 is 6′ × 5.5′ across. The Origin Mark II frames 1.32° × 0.75° at 1.23″ per pixel, so it fills 13% 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 | 21 min128 subs | 40 min240 subs | 2 h 02 min730 subs |
| 15 s | 21 min84 subs | 40 min159 subs | 2 h 01 min485 subs |
| 30 s | 20 min41 subs | 39 min79 subs | 2 h 01 min242 subs |
About the M61
A face-on barred spiral at the southern end of the Virgo cluster, with well-defined arms.
NGC 4303 · Galaxy in Virgo · magnitude 9.7 · 6′ × 5.5′ · 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 M61 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
- M61 with the ZWO Seestar S50: 3 h 07 min from Bortle 6
- M61 with the ZWO Seestar S50 Pro: 3 h 25 min from Bortle 6
- M61 with the ZWO Seestar S30: 3 h 17 min from Bortle 6
- M61 with the ZWO Seestar S30 Pro: 3 h 37 min from Bortle 6
- M61 with the DwarfLab DWARF 3: 4 h 32 min from Bortle 6
- M61 with the DwarfLab DWARF mini: 3 h 07 min from Bortle 6
- M61 with the DwarfLab Draco: 2 h 34 min from Bortle 6
- M61 with the DwarfLab DWARF II: 11 h from Bortle 6
- M61 with the Vaonis Vespera II: 3 h 07 min from Bortle 6
- M61 with the Vaonis Vespera Pro: 6 h 59 min from Bortle 6
- M61 with the Vaonis Vespera 3: 2 h 59 min from Bortle 6
- M61 with the Vaonis Vespera Pro 2: 6 h 40 min from Bortle 6
- M61 with the Unistellar eQuinox 2: 2 h 50 min from Bortle 6
- M61 with the Unistellar Odyssey: 13 h from Bortle 6
- M61 with the Celestron Origin: 50 min from Bortle 6
All telescopes for the M61 · All targets for the Origin Mark II