How long to image the M69 with the Celestron Origin Mark II

From a Bortle 6 suburban sky, the Celestron Origin Mark II needs about 6 min (38 subs of 10 s) for a solid image of the M69. A quick look takes 2 min; a showpiece 25 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 fills 22% of the frame’s short side.

M69 with the Celestron Origin Mark II: 10 s subs.
SkyQuick lookTarget obvious, still noisySolidClean enough to shareShowpieceSmooth faint detail, print-worthy
Bortle 1Excellent dark site2 min10 subs5 min30 subs15 min90 subs
Bortle 2Typical dark site2 min10 subs5 min30 subs15 min90 subs
Bortle 3Rural2 min10 subs5 min30 subs15 min90 subs
Bortle 4Rural / suburban transition2 min10 subs5 min30 subs15 min90 subs
Bortle 5Suburban2 min10 subs5 min30 subs16 min99 subs
Bortle 6Bright suburban2 min10 subs6 min38 subs25 min150 subs
Bortle 7Suburban / urban transition3 min16 subs10 min62 subs41 min247 subs
Bortle 8City4 min25 subs17 min100 subs1 h 06 min399 subs
Bortle 9Inner city8 min46 subs30 min181 subs2 h722 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 8 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.)

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How it frames

The M69 is 9.8′ across. The Origin Mark II frames 1.32° × 0.75° at 1.23″ per pixel, so it fills 22% 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 lengthBortle 3Bortle 5Bortle 7
10 s5 min30 subs5 min30 subs10 min62 subs
15 s8 min30 subs8 min30 subs10 min42 subs
30 s15 min30 subs15 min30 subs15 min30 subs

About the M69

A small, metal-rich globular near the Sagittarius teapot's base. Low from the north.

NGC 6637 · Globular cluster in Sagittarius · magnitude 7.6 · 9.8′ · best in Jun, Jul, Aug. Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.

Globular clusters are point sources packed tight, so they come quickly: the core resolves into stars within a handful of minutes on any smart scope. More time deepens the halo and pulls in the faint outer members. Use short subs so the core does not saturate into a white blob, and no filter.

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.

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Imaged the M69 with your Origin Mark II? Did the solid figure match?Anonymous, one tap. It is how the model gets calibrated.

Have an image of the M69 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

All telescopes for the M69 · All targets for the Origin Mark II