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

About 1 h 40 min of total integration for a solid image, or 6 h 40 min for a showpiece. A quick look takes 25 min.

How many subs is that on the Origin Mark II?

At the default 10 s sub length, 600 subs for a solid image from Bortle 6 and 168 from Bortle 3.

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

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

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

From a Bortle 6 suburban sky, the Celestron Origin Mark II needs about 1 h 40 min (600 subs of 10 s) for a solid image of the Pinwheel Galaxy. A quick look takes 25 min; a showpiece 6 h 40 min. Under a Bortle 3 rural sky the solid figure drops to 28 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 65% of the frame’s short side.

Pinwheel 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	5 min32 subs	21 min126 subs	1 h 23 min501 subs
Bortle 2Typical dark site	6 min35 subs	23 min140 subs	1 h 33 min559 subs
Bortle 3Rural	7 min42 subs	28 min168 subs	1 h 51 min669 subs
Bortle 4Rural / suburban transition	10 min59 subs	39 min235 subs	2 h 36 min937 subs
Bortle 5Suburban	14 min85 subs	57 min340 subs	3 h 47 min1,360 subs
Bortle 6Bright suburban	25 min150 subs	1 h 40 min600 subs	6 h 40 min2,399 subs
Bortle 7Suburban / urban transition	46 min274 subs	3 h 02 min1,095 subs	12 h4,379 subs
Bortle 8City	1 h 18 min466 subs	5 h 11 min1,864 subs	21 h7,453 subs
Bortle 9Inner city	2 h 26 min876 subs	9 h 44 min3,503 subs	39 h14,010 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 2 h 10 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 Pinwheel Galaxy is 29′ × 27′ across. The Origin Mark II frames 1.32° × 0.75° at 1.23″ per pixel, so it fills 65% 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	28 min168 subs	57 min340 subs	3 h 02 min1,095 subs
15 s	27 min109 subs	56 min224 subs	3 h 02 min728 subs
30 s	27 min54 subs	55 min111 subs	3 h 01 min363 subs

About the Pinwheel Galaxy

Big, face-on and faint. Its total magnitude is flattering; spread over half a degree the arms are dim and demand hours, especially from suburban skies.

M101, NGC 5457 · Galaxy in Ursa Major · magnitude 7.9 · 29′ × 27′ · best in Apr, May, Jun. 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 Pinwheel 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 Pinwheel 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 Pinwheel Galaxy · All targets for the Origin Mark II