How long to image the Triangulum Galaxy with the ZWO Seestar S30
From a Bortle 6 suburban sky, the ZWO Seestar S30 needs about 2 h 50 min (1,022 subs of 10 s) for a solid image of the Triangulum Galaxy. A quick look takes 43 min; a showpiece 11 h. Under a Bortle 3 rural sky the solid figure drops to 1 h 09 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 is just over the frame at 1.0×.
| Sky | Quick lookTarget obvious, still noisy | SolidClean enough to share | ShowpieceSmooth faint detail, print-worthy |
|---|---|---|---|
| Bortle 1Excellent dark site | 15 min89 subs | 59 min353 subs | 3 h 55 min1,410 subs |
| Bortle 2Typical dark site | 16 min94 subs | 1 h 02 min374 subs | 4 h 09 min1,493 subs |
| Bortle 3Rural | 17 min103 subs | 1 h 09 min412 subs | 4 h 35 min1,648 subs |
| Bortle 4Rural / suburban transition | 21 min127 subs | 1 h 24 min506 subs | 5 h 37 min2,024 subs |
| Bortle 5Suburban | 27 min164 subs | 1 h 49 min656 subs | 7 h 17 min2,621 subs |
| Bortle 6Bright suburban | 43 min256 subs | 2 h 50 min1,022 subs | 11 h4,085 subs |
| Bortle 7Suburban / urban transition | 1 h 12 min430 subs | 4 h 46 min1,719 subs | 19 h6,874 subs |
| Bortle 8City | 1 h 57 min701 subs | 7 h 47 min2,801 subs | 31 h11,204 subs |
| Bortle 9Inner city | 3 h 33 min1,278 subs | 14 h5,110 subs | 57 h20,440 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 3 h 41 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.
- Seestar S30 dew shieldHeater is built in; a cheap shield reduces dew and 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 S30 →
How it frames
The Triangulum Galaxy is 73′ × 45′ across. The Seestar S30 frames 2.13° × 1.20° at 3.99″ per pixel, so it is just over the frame at 1.0×. Point at the part you want; the edges will fall outside the frame.
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 | 1 h 09 min412 subs | 1 h 49 min656 subs | 4 h 46 min1,719 subs |
| 20 s | 55 min165 subs | 1 h 36 min287 subs | 4 h 33 min819 subs |
| 30 s | 50 min101 subs | 1 h 31 min182 subs | 4 h 28 min537 subs |
| 60 s | 46 min46 subs | 1 h 26 min87 subs | 4 h 24 min264 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 14 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 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.
Have an image of the Triangulum 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
- Triangulum Galaxy with the ZWO Seestar S50: 2 h 42 min from Bortle 6
- Triangulum Galaxy with the ZWO Seestar S50 Pro: 2 h 57 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 S30