How long to image the Whale Galaxy with the DwarfLab DWARF 3
From a Bortle 6 suburban sky, the DwarfLab DWARF 3 needs about 1 h 19 min (318 subs of 15 s) for a solid image of the Whale Galaxy. A quick look takes 20 min; a showpiece 5 h 17 min. Under a Bortle 3 rural sky the solid figure drops to 29 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 16% 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 | 6 min25 subs | 24 min97 subs | 1 h 36 min386 subs |
| Bortle 2Typical dark site | 6 min26 subs | 26 min104 subs | 1 h 43 min414 subs |
| Bortle 3Rural | 7 min30 subs | 29 min117 subs | 1 h 56 min465 subs |
| Bortle 4Rural / suburban transition | 9 min37 subs | 37 min148 subs | 2 h 27 min589 subs |
| Bortle 5Suburban | 12 min50 subs | 49 min197 subs | 3 h 16 min786 subs |
| Bortle 6Bright suburban | 20 min80 subs | 1 h 19 min318 subs | 5 h 17 min1,270 subs |
| Bortle 7Suburban / urban transition | 34 min137 subs | 2 h 17 min548 subs | 9 h 08 min2,191 subs |
| Bortle 8City | 57 min227 subs | 3 h 46 min906 subs | 15 h3,621 subs |
| Bortle 9Inner city | 1 h 44 min417 subs | 6 h 57 min1,668 subs | 28 h6,672 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 1 h 43 min of run time. The DWARF 3’s battery (rated about 5 h 30 min) should cover it; 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 Whale Galaxy is 15.5′ × 2.7′ across. The DWARF 3 frames 2.93° × 1.65° at 2.75″ per pixel, so it fills 16% 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 | 29 min117 subs | 49 min197 subs | 2 h 17 min548 subs |
| 30 s | 27 min55 subs | 47 min95 subs | 2 h 15 min271 subs |
| 60 s | 30 min30 subs | 46 min47 subs | 2 h 14 min135 subs |
Leave the dual-band filter out for the Whale 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 Whale Galaxy
A distorted edge-on galaxy with a small companion on its back, and the Hockey Stick (NGC 4656) in the same wide field.
NGC 4631, Caldwell 32 · Galaxy in Canes Venatici · magnitude 9.2 · 15.5′ × 2.7′ · best in Mar, Apr, May. 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 Whale 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
- Whale Galaxy with the ZWO Seestar S50: 55 min from Bortle 6
- Whale Galaxy with the ZWO Seestar S50 Pro: 1 h from Bortle 6
- Whale Galaxy with the ZWO Seestar S30: 57 min from Bortle 6
- Whale Galaxy with the ZWO Seestar S30 Pro: 1 h 03 min from Bortle 6
- Whale Galaxy with the DwarfLab DWARF mini: 54 min from Bortle 6
- Whale Galaxy with the DwarfLab Draco: 45 min from Bortle 6
- Whale Galaxy with the DwarfLab DWARF II: 3 h 06 min from Bortle 6
- Whale Galaxy with the Vaonis Vespera II: 55 min from Bortle 6
- Whale Galaxy with the Vaonis Vespera Pro: 2 h 02 min from Bortle 6
- Whale Galaxy with the Vaonis Vespera 3: 52 min from Bortle 6
- Whale Galaxy with the Vaonis Vespera Pro 2: 1 h 56 min from Bortle 6
- Whale Galaxy with the Unistellar eQuinox 2: 49 min from Bortle 6
- Whale Galaxy with the Unistellar Odyssey: 3 h 46 min from Bortle 6
- Whale Galaxy with the Celestron Origin: 14 min from Bortle 6
- Whale Galaxy with the Celestron Origin Mark II: 20 min from Bortle 6
All telescopes for the Whale Galaxy · All targets for the DWARF 3