How long should I image the Triangulum Galaxy with the Origin Mark II from a Bortle 6 sky?

About 59 min of total integration for a solid image, or 3 h 54 min for a showpiece. A quick look takes 15 min.

How many subs is that on the Origin Mark II?

At the default 10 s sub length, 352 subs for a solid image from Bortle 6 and 103 from Bortle 3.

Does a dual-band filter help on the Triangulum Galaxy?

No. The Triangulum Galaxy is a broadband target and a dual-band filter blocks most of its light. Shoot without a filter.

How long to image the Triangulum Galaxy with the Celestron Origin Mark II

From a Bortle 6 suburban sky, the Celestron Origin Mark II needs about 59 min (352 subs of 10 s) for a solid image of the Triangulum Galaxy. A quick look takes 15 min; a showpiece 3 h 54 min. Under a Bortle 3 rural sky the solid figure drops to 17 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 1.6× wider than the frame.

Triangulum Galaxy with the Celestron Origin Mark II: 10 s subs.
Sky	Quick lookTarget obvious, still noisy	SolidClean enough to share	ShowpieceSmooth faint detail, print-worthy
Bortle 1Excellent dark site	3 min20 subs	13 min79 subs	52 min314 subs
Bortle 2Typical dark site	4 min22 subs	14 min87 subs	58 min347 subs
Bortle 3Rural	4 min26 subs	17 min103 subs	1 h 08 min411 subs
Bortle 4Rural / suburban transition	6 min36 subs	23 min141 subs	1 h 34 min564 subs
Bortle 5Suburban	8 min51 subs	34 min202 subs	2 h 15 min808 subs
Bortle 6Bright suburban	15 min88 subs	59 min352 subs	3 h 54 min1,406 subs
Bortle 7Suburban / urban transition	27 min160 subs	1 h 46 min637 subs	7 h 04 min2,545 subs
Bortle 8City	45 min270 subs	3 h1,079 subs	12 h4,314 subs
Bortle 9Inner city	1 h 24 min506 subs	5 h 37 min2,022 subs	22 h8,087 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 1 h 16 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 Triangulum Galaxy is 73′ × 45′ across. The Origin Mark II frames 1.32° × 0.75° at 1.23″ per pixel, so it is 1.6× 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	17 min103 subs	34 min202 subs	1 h 46 min637 subs
15 s	17 min67 subs	33 min134 subs	1 h 46 min423 subs
30 s	16 min33 subs	33 min66 subs	1 h 45 min211 subs

About the Triangulum Galaxy

Big, face-on and low in surface brightness. Nearly as bright as M31 overall but spread thin, so it needs far more time. Its H II regions pop with a dual-band filter.

M33, NGC 598 · Galaxy in Triangulum · magnitude 5.7 · 73′ × 45′ · best in Sep, Oct, Nov. 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.

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.

Where to buy the Origin Mark IICelestron store Direct Amazon UK Amazon USThe Celestron store link is a plain link; the others are affiliate links. As an Amazon Associate I earn from qualifying purchases, at no cost to you.

Imaged the Triangulum Galaxy 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 Triangulum Galaxy 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 Triangulum Galaxy · All targets for the Origin Mark II