How long to image the Triangulum Galaxy with the ZWO Seestar S50
From a Bortle 6 suburban sky, the ZWO Seestar S50 needs about 2 h 42 min (971 subs of 10 s) for a solid image of the Triangulum Galaxy. A quick look takes 40 min; a showpiece 11 h. Under a Bortle 3 rural sky the solid figure drops to 1 h. 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 is 1.7× wider than the frame.
| Sky | Quick lookTarget obvious, still noisy | SolidClean enough to share | ShowpieceSmooth faint detail, print-worthy |
|---|---|---|---|
| Bortle 1Excellent dark site | 13 min76 subs | 50 min303 subs | 3 h 22 min1,210 subs |
| Bortle 2Typical dark site | 13 min81 subs | 54 min323 subs | 3 h 35 min1,292 subs |
| Bortle 3Rural | 15 min91 subs | 1 h362 subs | 4 h 01 min1,447 subs |
| Bortle 4Rural / suburban transition | 19 min114 subs | 1 h 16 min456 subs | 5 h 04 min1,824 subs |
| Bortle 5Suburban | 25 min152 subs | 1 h 41 min605 subs | 6 h 43 min2,420 subs |
| Bortle 6Bright suburban | 40 min243 subs | 2 h 42 min971 subs | 11 h3,884 subs |
| Bortle 7Suburban / urban transition | 1 h 10 min418 subs | 4 h 38 min1,669 subs | 19 h6,673 subs |
| Bortle 8City | 1 h 55 min688 subs | 7 h 38 min2,751 subs | 31 h11,004 subs |
| Bortle 9Inner city | 3 h 31 min1,265 subs | 14 h5,060 subs | 56 h20,239 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 3 h 30 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.
- Seestar S50 dew shieldThe built-in heater copes with most nights; a shield helps in heavy dew and blocks stray light.
- 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 Triangulum Galaxy is 73′ × 45′ across. The Seestar S50 frames 1.28° × 0.72° at 2.39″ per pixel, so it is 1.7× wider than the frame. A mosaic, or choosing the part you want and letting the rest go, is how it gets shot on this scope.
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 | 1 h362 subs | 1 h 41 min605 subs | 4 h 38 min1,669 subs |
| 20 s | 51 min153 subs | 1 h 31 min274 subs | 4 h 29 min806 subs |
| 30 s | 48 min96 subs | 1 h 28 min177 subs | 4 h 25 min531 subs |
| 60 s | 44 min45 subs | 1 h 25 min85 subs | 4 h 22 min263 subs |
Leave the dual-band filter out for the Triangulum 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 Triangulum Galaxy
Big, face-on and low in surface brightness. Nearly as bright as M31 overall but spread thin, so it needs far more time. Its H II regions pop with a dual-band filter.
M33, NGC 598 · Galaxy in Triangulum · magnitude 5.7 · 73′ × 45′ · best in Sep, Oct, Nov. 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.
Have an image of the Triangulum 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
- Triangulum Galaxy with the ZWO Seestar S50 Pro: 2 h 57 min from Bortle 6
- Triangulum Galaxy with the ZWO Seestar S30: 2 h 50 min from Bortle 6
- Triangulum Galaxy with the ZWO Seestar S30 Pro: 3 h 08 min from Bortle 6
- Triangulum Galaxy with the DwarfLab DWARF 3: 3 h 55 min from Bortle 6
- Triangulum Galaxy with the DwarfLab DWARF mini: 2 h 41 min from Bortle 6
- Triangulum Galaxy with the DwarfLab Draco: 2 h 13 min from Bortle 6
- Triangulum Galaxy with the DwarfLab DWARF II: 9 h 16 min from Bortle 6
- Triangulum Galaxy with the Vaonis Vespera II: 2 h 42 min from Bortle 6
- Triangulum Galaxy with the Vaonis Vespera Pro: 6 h 03 min from Bortle 6
- Triangulum Galaxy with the Vaonis Vespera 3: 2 h 35 min from Bortle 6
- Triangulum Galaxy with the Vaonis Vespera Pro 2: 5 h 46 min from Bortle 6
- Triangulum Galaxy with the Unistellar eQuinox 2: 2 h 28 min from Bortle 6
- Triangulum Galaxy with the Unistellar Odyssey: 11 h from Bortle 6
- Triangulum Galaxy with the Celestron Origin: 43 min from Bortle 6
- Triangulum Galaxy with the Celestron Origin Mark II: 59 min from Bortle 6
All telescopes for the Triangulum Galaxy · All targets for the Seestar S50