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

About 1 h 44 min of total integration for a solid image, or 6 h 55 min for a showpiece. A quick look takes 26 min.

How many subs is that on the Seestar S30?

At the default 10 s sub length, 623 subs for a solid image from Bortle 6 and 261 from Bortle 3.

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

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

How long to image the Sunflower Galaxy with the ZWO Seestar S30

From a Bortle 6 suburban sky, the ZWO Seestar S30 needs about 1 h 44 min (623 subs of 10 s) for a solid image of the Sunflower Galaxy. A quick look takes 26 min; a showpiece 6 h 55 min. Under a Bortle 3 rural sky the solid figure drops to 43 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 18% of the frame’s short side.

Sunflower 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	9 min57 subs	38 min226 subs	2 h 30 min901 subs
Bortle 2Typical dark site	10 min60 subs	40 min238 subs	2 h 38 min950 subs
Bortle 3Rural	11 min66 subs	43 min261 subs	2 h 54 min1,043 subs
Bortle 4Rural / suburban transition	13 min80 subs	53 min317 subs	3 h 31 min1,266 subs
Bortle 5Suburban	17 min102 subs	1 h 08 min406 subs	4 h 30 min1,621 subs
Bortle 6Bright suburban	26 min156 subs	1 h 44 min623 subs	6 h 55 min2,490 subs
Bortle 7Suburban / urban transition	43 min260 subs	2 h 53 min1,037 subs	12 h4,148 subs
Bortle 8City	1 h 10 min421 subs	4 h 40 min1,681 subs	19 h6,721 subs
Bortle 9Inner city	2 h 07 min763 subs	8 h 29 min3,052 subs	34 h12,208 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 2 h 15 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.)

USB-C power bank 10000mAh 5V 3A6,000 mAh inside; a 10,000 mAh 5 V 3 A bank roughly doubles a session.
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Seestar S30 dew shieldHeater is built in; a cheap shield reduces dew and 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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How it frames

The Sunflower Galaxy is 12.6′ × 7.2′ across. The Seestar S30 frames 2.13° × 1.20° at 3.99″ per pixel, so it fills 18% 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	43 min261 subs	1 h 08 min406 subs	2 h 53 min1,037 subs
20 s	35 min106 subs	59 min179 subs	2 h 45 min495 subs
30 s	33 min66 subs	57 min114 subs	2 h 42 min324 subs
60 s	30 min30 subs	54 min54 subs	2 h 39 min160 subs

Leave the dual-band filter out for the Sunflower 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 Sunflower Galaxy

A flocculent spiral whose arms break into patches like sunflower seeds. Bright core, subtle outer disc.

M63, NGC 5055 · Galaxy in Canes Venatici · magnitude 8.6 · 12.6′ × 7.2′ · 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

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 Sunflower 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 Sunflower 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 Sunflower Galaxy · All targets for the Seestar S30