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

About 2 h 19 min of total integration for a solid image, or 9 h 15 min for a showpiece. A quick look takes 35 min.

How many subs is that on the Seestar S30 Pro?

At the default 10 s sub length, 833 subs for a solid image from Bortle 6 and 345 from Bortle 3.

Does a dual-band filter help on the Antennae Galaxies?

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

How long to image the Antennae Galaxies with the ZWO Seestar S30 Pro

From a Bortle 6 suburban sky, the ZWO Seestar S30 Pro needs about 2 h 19 min (833 subs of 10 s) for a solid image of the Antennae Galaxies. A quick look takes 35 min; a showpiece 9 h 15 min. Under a Bortle 3 rural sky the solid figure drops to 57 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 4% of the frame’s short side.

Antennae Galaxies 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	12 min75 subs	50 min298 subs	3 h 18 min1,190 subs
Bortle 2Typical dark site	13 min79 subs	52 min314 subs	3 h 29 min1,256 subs
Bortle 3Rural	14 min87 subs	57 min345 subs	3 h 50 min1,380 subs
Bortle 4Rural / suburban transition	18 min106 subs	1 h 10 min421 subs	4 h 40 min1,681 subs
Bortle 5Suburban	22 min135 subs	1 h 30 min540 subs	6 h2,159 subs
Bortle 6Bright suburban	35 min209 subs	2 h 19 min833 subs	9 h 15 min3,330 subs
Bortle 7Suburban / urban transition	58 min348 subs	3 h 52 min1,391 subs	15 h5,562 subs
Bortle 8City	1 h 34 min565 subs	6 h 16 min2,257 subs	25 h9,027 subs
Bortle 9Inner city	2 h 51 min1,027 subs	11 h4,105 subs	46 h16,418 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 3 h 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.)

USB-C power bank 10000mAh 5V 3A5 V 3 A input and it runs while charging.
Amazon UK Amazon US
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.
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

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 Pro →

How it frames

The Antennae Galaxies is 5′ × 3′ across. The Seestar S30 Pro frames 3.99° × 2.24° at 3.74″ per pixel, so it fills 4% 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	57 min345 subs	1 h 30 min540 subs	3 h 52 min1,391 subs
20 s	49 min147 subs	1 h 21 min244 subs	3 h 43 min670 subs
30 s	46 min92 subs	1 h 18 min157 subs	3 h 40 min441 subs
60 s	43 min44 subs	1 h 16 min76 subs	3 h 37 min218 subs

Leave the dual-band filter out for the Antennae Galaxies. 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 Antennae Galaxies

Two colliding galaxies with long tidal tails. The cores are reachable; the antennae themselves are a dark-sky, long-integration task.

NGC 4038 and NGC 4039, Caldwell 60/61 · Galaxy in Corvus · magnitude 10.3 · 5′ × 3′ · 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 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 Antennae Galaxies 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 Antennae Galaxies 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 Antennae Galaxies · All targets for the Seestar S30 Pro