How long to image the Fireworks Galaxy with the ZWO Seestar S50
From a Bortle 6 suburban sky, the ZWO Seestar S50 needs about 5 h 15 min (1,893 subs of 10 s) for a solid image of the Fireworks Galaxy. A quick look takes 1 h 19 min; a showpiece 21 h. Under a Bortle 3 rural sky the solid figure drops to 1 h 55 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 26% of the frame’s short side.
| Sky | Quick lookTarget obvious, still noisy | SolidClean enough to share | ShowpieceSmooth faint detail, print-worthy |
|---|---|---|---|
| Bortle 1Excellent dark site | 24 min144 subs | 1 h 36 min575 subs | 6 h 23 min2,299 subs |
| Bortle 2Typical dark site | 26 min154 subs | 1 h 43 min616 subs | 6 h 50 min2,461 subs |
| Bortle 3Rural | 29 min173 subs | 1 h 55 min692 subs | 7 h 41 min2,767 subs |
| Bortle 4Rural / suburban transition | 37 min220 subs | 2 h 26 min878 subs | 9 h 45 min3,509 subs |
| Bortle 5Suburban | 49 min293 subs | 3 h 15 min1,172 subs | 13 h4,685 subs |
| Bortle 6Bright suburban | 1 h 19 min474 subs | 5 h 15 min1,893 subs | 21 h7,570 subs |
| Bortle 7Suburban / urban transition | 2 h 16 min817 subs | 9 h 04 min3,267 subs | 36 h13,068 subs |
| Bortle 8City | 3 h 45 min1,351 subs | 15 h5,401 subs | 60 h21,603 subs |
| Bortle 9Inner city | 6 h 55 min2,488 subs | 28 h9,952 subs | 110+ h39,807 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 6 h 50 min of run time. The Seestar S50’s battery is rated at about 6 h, so the session needs an external power bank. (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 Fireworks Galaxy is 11′ × 10′ across. The Seestar S50 frames 1.28° × 0.72° at 2.39″ per pixel, so it fills 26% 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 | 1 h 55 min692 subs | 3 h 15 min1,172 subs | 9 h 04 min3,267 subs |
| 20 s | 1 h 37 min290 subs | 2 h 56 min530 subs | 8 h 46 min1,578 subs |
| 30 s | 1 h 30 min181 subs | 2 h 50 min341 subs | 8 h 40 min1,040 subs |
| 60 s | 1 h 24 min85 subs | 2 h 44 min164 subs | 8 h 33 min514 subs |
Leave the dual-band filter out for the Fireworks 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 Fireworks Galaxy
A face-on spiral famous for its supernovae, dimmed by Milky Way dust. Faint arms; the open cluster NGC 6939 sits nearby.
NGC 6946, Caldwell 12 · Galaxy in Cygnus · magnitude 9.6 · 11′ × 10′ · best in Jul, Aug, Sep. 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 Fireworks 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
- Fireworks Galaxy with the ZWO Seestar S50 Pro: 5 h 45 min from Bortle 6
- Fireworks Galaxy with the ZWO Seestar S30: 5 h 32 min from Bortle 6
- Fireworks Galaxy with the ZWO Seestar S30 Pro: 6 h 06 min from Bortle 6
- Fireworks Galaxy with the DwarfLab DWARF 3: 7 h 37 min from Bortle 6
- Fireworks Galaxy with the DwarfLab DWARF mini: 5 h 14 min from Bortle 6
- Fireworks Galaxy with the DwarfLab Draco: 4 h 19 min from Bortle 6
- Fireworks Galaxy with the DwarfLab DWARF II: 18 h from Bortle 6
- Fireworks Galaxy with the Vaonis Vespera II: 5 h 15 min from Bortle 6
- Fireworks Galaxy with the Vaonis Vespera Pro: 12 h from Bortle 6
- Fireworks Galaxy with the Vaonis Vespera 3: 5 h 01 min from Bortle 6
- Fireworks Galaxy with the Vaonis Vespera Pro 2: 11 h from Bortle 6
- Fireworks Galaxy with the Unistellar eQuinox 2: 4 h 49 min from Bortle 6
- Fireworks Galaxy with the Unistellar Odyssey: 22 h from Bortle 6
- Fireworks Galaxy with the Celestron Origin: 1 h 23 min from Bortle 6
- Fireworks Galaxy with the Celestron Origin Mark II: 1 h 54 min from Bortle 6
All telescopes for the Fireworks Galaxy · All targets for the Seestar S50