How long to image the Pinwheel Galaxy with the DwarfLab DWARF mini
From a Bortle 6 suburban sky, the DwarfLab DWARF mini needs about 4 h 35 min (1,102 subs of 15 s) for a solid image of the Pinwheel Galaxy. A quick look takes 1 h 09 min; a showpiece 18 h. Under a Bortle 3 rural sky the solid figure drops to 1 h 39 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 40% 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 | 20 min82 subs | 1 h 22 min328 subs | 5 h 27 min1,309 subs |
| Bortle 2Typical dark site | 22 min88 subs | 1 h 28 min351 subs | 5 h 51 min1,404 subs |
| Bortle 3Rural | 25 min99 subs | 1 h 39 min396 subs | 6 h 36 min1,584 subs |
| Bortle 4Rural / suburban transition | 32 min127 subs | 2 h 06 min505 subs | 8 h 25 min2,020 subs |
| Bortle 5Suburban | 42 min170 subs | 2 h 49 min678 subs | 11 h2,711 subs |
| Bortle 6Bright suburban | 1 h 09 min276 subs | 4 h 35 min1,102 subs | 18 h4,407 subs |
| Bortle 7Suburban / urban transition | 1 h 59 min478 subs | 7 h 57 min1,910 subs | 32 h7,638 subs |
| Bortle 8City | 3 h 18 min791 subs | 13 h3,164 subs | 53 h12,655 subs |
| Bortle 9Inner city | 6 h 05 min1,460 subs | 24 h5,839 subs | 97 h23,355 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 5 h 58 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 Pinwheel Galaxy is 29′ × 27′ across. The DWARF mini frames 2.13° × 1.20° at 3.99″ per pixel, so it fills 40% 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 39 min396 subs | 2 h 49 min678 subs | 7 h 57 min1,910 subs |
| 30 s | 1 h 23 min167 subs | 2 h 34 min308 subs | 7 h 42 min924 subs |
| 60 s | 1 h 15 min76 subs | 2 h 26 min146 subs | 7 h 34 min454 subs |
| 90 s | 1 h 13 min49 subs | 2 h 23 min96 subs | 7 h 31 min301 subs |
Leave the dual-band filter out for the Pinwheel 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 Pinwheel Galaxy
Big, face-on and faint. Its total magnitude is flattering; spread over half a degree the arms are dim and demand hours, especially from suburban skies.
M101, NGC 5457 · Galaxy in Ursa Major · magnitude 7.9 · 29′ × 27′ · best in Apr, May, Jun. 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 Pinwheel 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
- Pinwheel Galaxy with the ZWO Seestar S50: 4 h 37 min from Bortle 6
- Pinwheel Galaxy with the ZWO Seestar S50 Pro: 5 h 03 min from Bortle 6
- Pinwheel Galaxy with the ZWO Seestar S30: 4 h 51 min from Bortle 6
- Pinwheel Galaxy with the ZWO Seestar S30 Pro: 5 h 21 min from Bortle 6
- Pinwheel Galaxy with the DwarfLab DWARF 3: 6 h 41 min from Bortle 6
- Pinwheel Galaxy with the DwarfLab Draco: 3 h 47 min from Bortle 6
- Pinwheel Galaxy with the DwarfLab DWARF II: 16 h from Bortle 6
- Pinwheel Galaxy with the Vaonis Vespera II: 4 h 37 min from Bortle 6
- Pinwheel Galaxy with the Vaonis Vespera Pro: 10 h from Bortle 6
- Pinwheel Galaxy with the Vaonis Vespera 3: 4 h 24 min from Bortle 6
- Pinwheel Galaxy with the Vaonis Vespera Pro 2: 9 h 52 min from Bortle 6
- Pinwheel Galaxy with the Unistellar eQuinox 2: 4 h 14 min from Bortle 6
- Pinwheel Galaxy with the Unistellar Odyssey: 20 h from Bortle 6
- Pinwheel Galaxy with the Celestron Origin: 1 h 13 min from Bortle 6
- Pinwheel Galaxy with the Celestron Origin Mark II: 1 h 40 min from Bortle 6
All telescopes for the Pinwheel Galaxy · All targets for the DWARF mini