How long should I image the Cigar Galaxy with the Seestar S50 from a Bortle 6 sky?

About 35 min of total integration for a solid image, or 2 h 18 min for a showpiece. A quick look takes 9 min.

How many subs is that on the Seestar S50?

At the default 10 s sub length, 208 subs for a solid image from Bortle 6 and 91 from Bortle 3.

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

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

How long to image the Cigar Galaxy with the ZWO Seestar S50

From a Bortle 6 suburban sky, the ZWO Seestar S50 needs about 35 min (208 subs of 10 s) for a solid image of the Cigar Galaxy. A quick look takes 9 min; a showpiece 2 h 18 min. Under a Bortle 3 rural sky the solid figure drops to 15 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 26% of the frame’s short side.

Cigar Galaxy with the ZWO Seestar S50: 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 min315 subs
Bortle 2Typical dark site	3 min21 subs	14 min83 subs	55 min331 subs
Bortle 3Rural	4 min23 subs	15 min91 subs	1 h361 subs
Bortle 4Rural / suburban transition	5 min28 subs	18 min109 subs	1 h 12 min433 subs
Bortle 5Suburban	6 min35 subs	23 min137 subs	1 h 31 min548 subs
Bortle 6Bright suburban	9 min52 subs	35 min208 subs	2 h 18 min830 subs
Bortle 7Suburban / urban transition	14 min86 subs	57 min342 subs	3 h 48 min1,367 subs
Bortle 8City	23 min138 subs	1 h 32 min550 subs	6 h 07 min2,200 subs
Bortle 9Inner city	41 min249 subs	2 h 46 min995 subs	11 h3,978 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 45 min of run time. The Seestar S50’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, and 30% off the battery for a February night.)

USB-C power bank 20000mAh 5V 3AThe S50 draws 5 V 3 A over USB-C and runs while charging; no PD needed.
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Seestar S50 dew shieldThe built-in heater copes with most nights; a shield helps in heavy dew and blocks stray light.
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red LED head torchRed light keeps your night vision; white light costs you twenty minutes of dark adaptation every time.
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hand warmers long lastingAir-activated packs give hours of heat for the person; winter nights are long and you spend most of them standing still.
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How it frames

The Cigar Galaxy is 11′ × 4′ across. The Seestar S50 frames 1.28° × 0.72° at 2.39″ per pixel, so it fills 26% of the frame’s short side.

Longer subs

10, 20 and 30 s in Alt-Az; 60 s only in EQ mode (app 2.5 and later). Time for a solid image by sub length:

Sub length	Bortle 3	Bortle 5	Bortle 7
10 s	15 min91 subs	23 min137 subs	57 min342 subs
20 s	13 min40 subs	21 min63 subs	55 min166 subs
30 s	15 min30 subs	20 min41 subs	54 min109 subs
60 s	30 min30 subs	30 min30 subs	54 min54 subs

Leave the dual-band filter out for the Cigar Galaxy. It is a galaxy, and it shines right across the spectrum. A dual-band filter keeps two emission lines and throws the rest away, so most of the light you came for is being stopped along with the sky. From a Bortle 6 sky it would be roughly 11 times slower.

About the Cigar Galaxy

An edge-on starburst galaxy with red hydrogen jets bursting from its core. Dual-band pulls the jets out of the glare.

M82, NGC 3034 · Galaxy in Ursa Major · magnitude 8.4 · 11′ × 4′ · best in Jan, Feb, Mar. 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 ZWO Seestar S50

The scope that made smart astrophotography mainstream. 50 mm triplet, 2 MP sensor, dual-band filter on a wheel. Alt-Az stacking at 10 s, EQ mode unlocks 60 s. Out of production since 2026 and replaced by the S50 Pro, but there are a great many in use.

10, 20 and 30 s in Alt-Az; 60 s only in EQ mode (app 2.5 and later). Built-in dual-band light-pollution filter, switchable in the app.

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 60 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 Seestar S50ZWO store Direct Amazon UK Amazon USThe ZWO 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 Cigar Galaxy with your Seestar S50? Did the solid figure match?Anonymous, one tap. It is how the model gets calibrated.

Have an image of the Cigar Galaxy from a Seestar S50? Email it with your total time and sky to [email protected] and it goes here, credited.

Same target, other telescopes

All telescopes for the Cigar Galaxy · All targets for the Seestar S50