How long should I image the Whirlpool Galaxy with the Origin from a Bortle 6 sky?

About 16 min of total integration for a solid image, or 1 h 02 min for a showpiece. A quick look takes 4 min.

How many subs is that on the Origin?

At the default 10 s sub length, 94 subs for a solid image from Bortle 6 and 35 from Bortle 3.

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

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

How long to image the Whirlpool Galaxy with the Celestron Origin

From a Bortle 6 suburban sky, the Celestron Origin needs about 16 min (94 subs of 10 s) for a solid image of the Whirlpool Galaxy. A quick look takes 4 min; a showpiece 1 h 02 min. Under a Bortle 3 rural sky the solid figure drops to 6 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 21% of the frame’s short side.

Whirlpool Galaxy with the Celestron Origin: 10 s subs.
Sky	Quick lookTarget obvious, still noisy	SolidClean enough to share	ShowpieceSmooth faint detail, print-worthy
Bortle 1Excellent dark site	2 min10 subs	5 min30 subs	19 min116 subs
Bortle 2Typical dark site	2 min10 subs	5 min31 subs	21 min124 subs
Bortle 3Rural	2 min10 subs	6 min35 subs	23 min139 subs
Bortle 4Rural / suburban transition	2 min11 subs	7 min44 subs	29 min175 subs
Bortle 5Suburban	2 min15 subs	10 min58 subs	39 min232 subs
Bortle 6Bright suburban	4 min24 subs	16 min94 subs	1 h 02 min373 subs
Bortle 7Suburban / urban transition	7 min41 subs	27 min161 subs	1 h 47 min642 subs
Bortle 8City	11 min67 subs	44 min265 subs	2 h 56 min1,058 subs
Bortle 9Inner city	20 min122 subs	1 h 21 min487 subs	5 h 24 min1,947 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 20 min of run time. The Origin’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 Whirlpool Galaxy is 11′ × 7′ across. The Origin frames 1.27° × 0.85° at 1.48″ per pixel, so it fills 21% 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. Time for a solid image by sub length:

Sub length	Bortle 3	Bortle 5	Bortle 7
10 s	6 min35 subs	10 min58 subs	27 min161 subs
15 s	8 min30 subs	9 min38 subs	26 min106 subs
30 s	15 min30 subs	15 min30 subs	26 min53 subs

About the Whirlpool Galaxy

The classic face-on spiral with its companion tugging at one arm. Small in a smart scope but bright; the arms appear within an hour, the tidal bridge needs several.

M51, NGC 5194 · Galaxy in Canes Venatici · magnitude 8.4 · 11′ × 7′ · 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

The first-generation Origin: a 6-inch f/2.2 RASA in a smart package and the fastest system here by a wide margin. Superseded by the Mark II in late 2025 and no longer sold new; Celestron offers a camera upgrade to the Mark II sensor.

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. 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 Whirlpool Galaxy with your Origin? Did the solid figure match?Anonymous, one tap. It is how the model gets calibrated.

Have an image of the Whirlpool Galaxy from a Origin? Email it with your total time and sky to [email protected] and it goes here, credited.

Same target, other telescopes

All telescopes for the Whirlpool Galaxy · All targets for the Origin