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

About 36 min of total integration for a solid image, or 2 h 25 min for a showpiece. A quick look takes 9 min.

How many subs is that on the Seestar S30?

At the default 10 s sub length, 218 subs for a solid image from Bortle 6 and 100 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

From a Bortle 6 suburban sky, the ZWO Seestar S30 needs about 36 min (218 subs of 10 s) for a solid image of the Cigar Galaxy. A quick look takes 9 min; a showpiece 2 h 25 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 fills 15% of the frame’s short side.

Cigar Galaxy with the ZWO Seestar S30: 10 s subs.
Sky	Quick lookTarget obvious, still noisy	SolidClean enough to share	ShowpieceSmooth faint detail, print-worthy
Bortle 1Excellent dark site	4 min23 subs	15 min89 subs	59 min354 subs
Bortle 2Typical dark site	4 min24 subs	15 min93 subs	1 h 02 min370 subs
Bortle 3Rural	4 min25 subs	17 min100 subs	1 h 07 min400 subs
Bortle 4Rural / suburban transition	5 min30 subs	20 min118 subs	1 h 19 min472 subs
Bortle 5Suburban	6 min37 subs	24 min147 subs	1 h 38 min587 subs
Bortle 6Bright suburban	9 min55 subs	36 min218 subs	2 h 25 min869 subs
Bortle 7Suburban / urban transition	15 min88 subs	59 min352 subs	3 h 54 min1,405 subs
Bortle 8City	23 min140 subs	1 h 33 min560 subs	6 h 13 min2,239 subs
Bortle 9Inner city	42 min252 subs	2 h 47 min1,005 subs	11 h4,017 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 47 min of run time. The Seestar S30’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 10000mAh 5V 3A6,000 mAh inside; a 10,000 mAh 5 V 3 A bank roughly doubles a session.
Amazon UK Amazon US
Seestar S30 dew shieldHeater is built in; a cheap shield reduces dew and stray light.
Amazon UK Amazon US
red LED head torchRed light keeps your night vision; white light costs you twenty minutes of dark adaptation every time.
Amazon UK Amazon US
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.
Amazon UK Amazon US

Affiliate links: the retailer pays us a small commission and you pay the same price. These are search links to the named product, not endorsements of a particular listing; check the listing matches your model.

Everything that fits the Seestar S30 →

How it frames

The Cigar Galaxy is 11′ × 4′ across. The Seestar S30 frames 2.13° × 1.20° at 3.99″ per pixel, so it fills 15% 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	17 min100 subs	24 min147 subs	59 min352 subs
20 s	14 min42 subs	22 min66 subs	56 min168 subs
30 s	15 min30 subs	21 min42 subs	55 min111 subs
60 s	30 min30 subs	30 min30 subs	54 min55 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 13 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

Wider and lighter than the S50 with the same 2.9 µm pixels, so its per-pixel speed on extended targets is close despite the smaller aperture. Ideal for big nebulae.

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.

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 S30ZWO 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? 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? 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