How long to image the Pinwheel Galaxy with the DwarfLab DWARF 3
From a Bortle 6 suburban sky, the DwarfLab DWARF 3 needs about 6 h 41 min (1,604 subs of 15 s) for a solid image of the Pinwheel Galaxy. A quick look takes 1 h 40 min; a showpiece 27 h. Under a Bortle 3 rural sky the solid figure drops to 2 h 08 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 29% 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 | 25 min102 subs | 1 h 42 min408 subs | 6 h 47 min1,629 subs |
| Bortle 2Typical dark site | 28 min111 subs | 1 h 51 min444 subs | 7 h 24 min1,776 subs |
| Bortle 3Rural | 32 min129 subs | 2 h 08 min514 subs | 8 h 33 min2,054 subs |
| Bortle 4Rural / suburban transition | 43 min171 subs | 2 h 50 min682 subs | 11 h2,728 subs |
| Bortle 5Suburban | 59 min238 subs | 3 h 57 min949 subs | 16 h3,796 subs |
| Bortle 6Bright suburban | 1 h 40 min401 subs | 6 h 41 min1,604 subs | 27 h6,415 subs |
| Bortle 7Suburban / urban transition | 2 h 58 min713 subs | 12 h2,852 subs | 48 h11,407 subs |
| Bortle 8City | 4 h 59 min1,198 subs | 20 h4,789 subs | 80 h19,156 subs |
| Bortle 9Inner city | 9 h 18 min2,231 subs | 37 h8,921 subs | 150+ h35,684 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 8 h 41 min of run time. That is more than one night: over 2 nights, about 4 h 21 min each. The DWARF 3’s battery (rated about 5 h 30 min) 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 PD power bank 20000mAh 18W18 W PD input and it runs while charging; needs a C-to-C cable for PD.
- 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 3 →
How it frames
The Pinwheel Galaxy is 29′ × 27′ across. The DWARF 3 frames 2.93° × 1.65° at 2.75″ per pixel, so it fills 29% of the frame’s short side.
Longer subs
Auto mode caps subs at 15 s; 30 s and longer need EQ mode, and 60 s is the ceiling on the tele camera. Time for a solid image by sub length:
| Sub length | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| 15 s | 2 h 08 min514 subs | 3 h 57 min949 subs | 12 h2,852 subs |
| 30 s | 1 h 59 min238 subs | 3 h 48 min456 subs | 12 h1,407 subs |
| 60 s | 1 h 54 min115 subs | 3 h 43 min224 subs | 12 h699 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 10 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 3
Small pixels on a 35 mm f/4.3 lens give a sharper image than its aperture suggests, and EQ mode with 60 s subs makes it the read-noise winner in dark skies.
Auto mode caps subs at 15 s; 30 s and longer need EQ mode, and 60 s is the ceiling on the tele camera. Three built-in filters: VIS, Astro (430 to 690 nm) and dual-band Hα 656 nm / OIII 501 nm.
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 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 Pinwheel Galaxy from a DWARF 3? 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 mini: 4 h 35 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 3