How long to image the Fireworks Galaxy with the DwarfLab DWARF mini
From a Bortle 6 suburban sky, the DwarfLab DWARF mini needs about 5 h 14 min (1,256 subs of 15 s) for a solid image of the Fireworks Galaxy. A quick look takes 1 h 18 min; a showpiece 21 h. Under a Bortle 3 rural sky the solid figure drops to 1 h 54 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 | 24 min95 subs | 1 h 34 min378 subs | 6 h 17 min1,509 subs |
| Bortle 2Typical dark site | 25 min102 subs | 1 h 41 min405 subs | 6 h 44 min1,617 subs |
| Bortle 3Rural | 28 min114 subs | 1 h 54 min456 subs | 7 h 35 min1,821 subs |
| Bortle 4Rural / suburban transition | 36 min145 subs | 2 h 25 min579 subs | 9 h 39 min2,316 subs |
| Bortle 5Suburban | 48 min194 subs | 3 h 14 min775 subs | 13 h3,100 subs |
| Bortle 6Bright suburban | 1 h 18 min314 subs | 5 h 14 min1,256 subs | 21 h5,023 subs |
| Bortle 7Suburban / urban transition | 2 h 16 min543 subs | 9 h 03 min2,172 subs | 36 h8,688 subs |
| Bortle 8City | 3 h 45 min899 subs | 15 h3,595 subs | 60 h14,378 subs |
| Bortle 9Inner city | 6 h 54 min1,658 subs | 28 h6,629 subs | 110+ h26,514 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 6 h 48 min of run time. The DWARF mini’s battery is rated at about 3 h 30 min, so the session needs an external power bank. (Bortle 6, solid image; we allow 30% over the integration time.)
- USB-C PD power bank 10000mAh 20W7,000 mAh inside, about four hours; a PD bank extends the night.
- 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 DWARF mini →
How it frames
The Fireworks Galaxy is 11′ × 10′ across. The DWARF mini frames 2.13° × 1.20° at 3.99″ per pixel, so it fills 15% of the frame’s short side.
Longer subs
Auto mode caps subs at 15 s; 30 s and longer need EQ mode, and 90 s is the ceiling. Time for a solid image by sub length:
| Sub length | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| 15 s | 1 h 54 min456 subs | 3 h 14 min775 subs | 9 h 03 min2,172 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 |
| 90 s | 1 h 24 min56 subs | 2 h 44 min110 subs | 8 h 33 min343 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 DwarfLab DWARF mini
DwarfLab’s answer to the Seestar S30: same sensor and focal length, big pixels, dual-band filter built in, and 90 s subs in EQ mode. Sensitivity over megapixels.
Auto mode caps subs at 15 s; 30 s and longer need EQ mode, and 90 s is the ceiling. Built-in Astro (430 to 690 nm), dark-frame and dual-band Hα / OIII filters; no plain VIS filter on the tele camera.
Longer subs matter most under dark skies, where read noise rather than skyglow sets the floor. From a city the difference between 15 s and 90 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 DWARF mini? 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: 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 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 DWARF mini