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

About 1 h 06 min of total integration for a solid image, or 4 h 24 min for a showpiece. A quick look takes 16 min.

How many subs is that on the Seestar S50?

At the default 10 s sub length, 396 subs for a solid image from Bortle 6 and 157 from Bortle 3.

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

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

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

From a Bortle 6 suburban sky, the ZWO Seestar S50 needs about 1 h 06 min (396 subs of 10 s) for a solid image of the Needle Galaxy. A quick look takes 16 min; a showpiece 4 h 24 min. Under a Bortle 3 rural sky the solid figure drops to 26 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 37% of the frame’s short side.

Needle 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	6 min34 subs	22 min134 subs	1 h 29 min534 subs
Bortle 2Typical dark site	6 min36 subs	24 min142 subs	1 h 34 min566 subs
Bortle 3Rural	7 min40 subs	26 min157 subs	1 h 44 min627 subs
Bortle 4Rural / suburban transition	8 min49 subs	32 min194 subs	2 h 09 min775 subs
Bortle 5Suburban	11 min64 subs	42 min253 subs	2 h 48 min1,009 subs
Bortle 6Bright suburban	16 min99 subs	1 h 06 min396 subs	4 h 24 min1,582 subs
Bortle 7Suburban / urban transition	28 min168 subs	1 h 51 min669 subs	7 h 26 min2,675 subs
Bortle 8City	46 min274 subs	3 h 02 min1,093 subs	12 h4,372 subs
Bortle 9Inner city	1 h 23 min500 subs	5 h 33 min1,998 subs	22 h7,990 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 1 h 26 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.)

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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Everything that fits the Seestar S50 →

How it frames

The Needle Galaxy is 16′ × 2′ across. The Seestar S50 frames 1.28° × 0.72° at 2.39″ per pixel, so it fills 37% 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	26 min157 subs	42 min253 subs	1 h 51 min669 subs
20 s	22 min68 subs	38 min115 subs	1 h 48 min324 subs
30 s	21 min43 subs	37 min75 subs	1 h 46 min213 subs
60 s	30 min30 subs	36 min36 subs	1 h 45 min106 subs

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

The finest edge-on spiral in the northern sky, a thin needle with a central bulge and dust lane.

NGC 4565, Caldwell 38 · Galaxy in Coma Berenices · magnitude 9.6 · 16′ × 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 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 Needle 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 Needle 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 Needle Galaxy · All targets for the Seestar S50