How long to image the Fireworks Galaxy with the ZWO Seestar S30
From a Bortle 6 suburban sky, the ZWO Seestar S30 needs about 5 h 32 min (1,992 subs of 10 s) for a solid image of the Fireworks Galaxy. A quick look takes 1 h 23 min; a showpiece 22 h. Under a Bortle 3 rural sky the solid figure drops to 2 h 12 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 15% 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 | 28 min169 subs | 1 h 52 min674 subs | 7 h 29 min2,694 subs |
| Bortle 2Typical dark site | 30 min179 subs | 1 h 59 min714 subs | 7 h 56 min2,856 subs |
| Bortle 3Rural | 33 min198 subs | 2 h 12 min791 subs | 8 h 47 min3,163 subs |
| Bortle 4Rural / suburban transition | 41 min245 subs | 2 h 43 min977 subs | 11 h3,905 subs |
| Bortle 5Suburban | 53 min318 subs | 3 h 32 min1,270 subs | 14 h5,080 subs |
| Bortle 6Bright suburban | 1 h 23 min498 subs | 5 h 32 min1,992 subs | 22 h7,966 subs |
| Bortle 7Suburban / urban transition | 2 h 20 min842 subs | 9 h 21 min3,366 subs | 37 h13,463 subs |
| Bortle 8City | 3 h 49 min1,375 subs | 15 h5,500 subs | 61 h21,999 subs |
| Bortle 9Inner city | 6 h 59 min2,513 subs | 28 h10,051 subs | 110+ h40,203 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 7 h 11 min of run time. That is more than one night: over 2 nights, about 3 h 36 min each. The Seestar S30’s battery (rated about 6 h) should cover each night; 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 Fireworks Galaxy is 11′ × 10′ across. The Seestar S30 frames 2.13° × 1.20° at 3.99″ per pixel, so it fills 15% 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 | 2 h 12 min791 subs | 3 h 32 min1,270 subs | 9 h 21 min3,366 subs |
| 20 s | 1 h 45 min315 subs | 3 h 05 min555 subs | 8 h 54 min1,602 subs |
| 30 s | 1 h 36 min192 subs | 2 h 56 min352 subs | 8 h 45 min1,050 subs |
| 60 s | 1 h 27 min87 subs | 2 h 47 min167 subs | 8 h 36 min517 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 14 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 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 Fireworks 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
- Fireworks Galaxy with the ZWO Seestar S50: 5 h 15 min from Bortle 6
- Fireworks Galaxy with the ZWO Seestar S50 Pro: 5 h 45 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 S30