How long should I image the Cigar Galaxy with the Seestar S30 Pro from a Bortle 6 sky?

About 40 min of total integration for a solid image, or 2 h 40 min for a showpiece. A quick look takes 10 min.

How many subs is that on the Seestar S30 Pro?

At the default 10 s sub length, 241 subs for a solid image from Bortle 6 and 107 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 S30 Pro

From a Bortle 6 suburban sky, the ZWO Seestar S30 Pro needs about 40 min (241 subs of 10 s) for a solid image of the Cigar Galaxy. A quick look takes 10 min; a showpiece 2 h 40 min. Under a Bortle 3 rural sky the solid figure drops to 18 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 8% of the frame’s short side.

Cigar Galaxy with the ZWO Seestar S30 Pro: 10 s subs.
Sky	Quick lookTarget obvious, still noisy	SolidClean enough to share	ShowpieceSmooth faint detail, print-worthy
Bortle 1Excellent dark site	4 min24 subs	16 min94 subs	1 h 02 min375 subs
Bortle 2Typical dark site	4 min25 subs	16 min99 subs	1 h 05 min393 subs
Bortle 3Rural	4 min27 subs	18 min107 subs	1 h 11 min427 subs
Bortle 4Rural / suburban transition	5 min32 subs	21 min128 subs	1 h 25 min510 subs
Bortle 5Suburban	7 min40 subs	27 min160 subs	1 h 47 min640 subs
Bortle 6Bright suburban	10 min61 subs	40 min241 subs	2 h 40 min961 subs
Bortle 7Suburban / urban transition	16 min99 subs	1 h 05 min393 subs	4 h 22 min1,572 subs
Bortle 8City	26 min158 subs	1 h 45 min630 subs	7 h2,520 subs
Bortle 9Inner city	47 min284 subs	3 h 09 min1,136 subs	13 h4,543 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 52 min of run time. The Seestar S30 Pro’s battery (rated about 5 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 10000mAh 5V 3A5 V 3 A input and it runs while charging.
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Seestar S30 Pro dew shieldActive anti-dew is built in; a shield adds margin. The S30 Pro front differs from the S30, so check the listing.
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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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How it frames

The Cigar Galaxy is 11′ × 4′ across. The Seestar S30 Pro frames 3.99° × 2.24° at 3.74″ per pixel, so it fills 8% of the frame’s short side.

Longer subs

10, 20 and 30 s in Alt-Az; 60 s only in EQ mode, which needs the TH10 head. Time for a solid image by sub length:

Sub length	Bortle 3	Bortle 5	Bortle 7
10 s	18 min107 subs	27 min160 subs	1 h 05 min393 subs
20 s	15 min47 subs	24 min73 subs	1 h 03 min190 subs
30 s	15 min30 subs	23 min47 subs	1 h 02 min125 subs
60 s	30 min30 subs	30 min30 subs	1 h 02 min62 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 12 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 S30 Pro

The S30 optics upgraded to a quadruplet in front of an 8 MP IMX585. Same speed per pixel as the S30, four times the pixels, so you can crop hard.

10, 20 and 30 s in Alt-Az; 60 s only in EQ mode, which needs the TH10 head. Built-in UV/IR-cut, dual-band (OIII 30 nm / Hα 20 nm) and dark filters on the telephoto camera.

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 S30 ProZWO 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 S30 Pro? 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 S30 Pro? 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 S30 Pro