How long to image the NGC 2903 with the DwarfLab DWARF II
From a Bortle 6 suburban sky, the DwarfLab DWARF II needs about 8 h 04 min (1,936 subs of 15 s) for a solid image of the NGC 2903. A quick look takes 2 h 01 min; a showpiece 32 h. Under a Bortle 3 rural sky the solid figure drops to 4 h 01 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it fills 12% 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 | 54 min218 subs | 3 h 37 min869 subs | 14 h3,474 subs |
| Bortle 2Typical dark site | 56 min226 subs | 3 h 45 min902 subs | 15 h3,606 subs |
| Bortle 3Rural | 1 h241 subs | 4 h 01 min964 subs | 16 h3,854 subs |
| Bortle 4Rural / suburban transition | 1 h 10 min279 subs | 4 h 38 min1,114 subs | 19 h4,455 subs |
| Bortle 5Suburban | 1 h 24 min338 subs | 5 h 38 min1,352 subs | 23 h5,407 subs |
| Bortle 6Bright suburban | 2 h 01 min484 subs | 8 h 04 min1,936 subs | 32 h7,744 subs |
| Bortle 7Suburban / urban transition | 3 h 11 min763 subs | 13 h3,049 subs | 51 h12,196 subs |
| Bortle 8City | 4 h 59 min1,195 subs | 20 h4,778 subs | 80 h19,110 subs |
| Bortle 9Inner city | 8 h 49 min2,116 subs | 35 h8,464 subs | 140+ h33,854 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 10 h of run time. That is more than one night: over 2 nights, about 5 h 15 min each. The DWARF II’s battery is rated at about 3 h, less near freezing, so each night needs an external power bank. (Bortle 6, solid image; we allow 30% over the integration time, and 30% off the battery for a February night.)
- USB-C PD power bank 10000mAh 18W18 W PD input; runs while charging.
- red LED head torchRed light keeps your night vision; white light costs you twenty minutes of dark adaptation every time.
- hand warmers long lastingAir-activated packs give hours of heat for the person; winter nights are long and you spend most of them standing still.
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Everything that fits the DWARF II →
How it frames
The NGC 2903 is 12.6′ × 6′ across. The DWARF II frames 3.19° × 1.79° at 2.99″ per pixel, so it fills 12% of the frame’s short side.
About the NGC 2903
A bright barred spiral below the Sickle of Leo that Messier somehow missed. Bright core, well-defined arms.
UGC 5079 · Galaxy in Leo · magnitude 9.0 · 12.6′ × 6′ · best in Jan, Feb, Mar. 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 II
The original pocket scope. 24 mm aperture and tiny 1.45 µm pixels mean it is slow per pixel, so bin or downsample and be patient.
15 s is the hard maximum in any mode; DwarfLab recommends EQ mode at 15 s. Two built-in filters, VIS and Astro (IR-pass); no dual-band. The optional UHC filter is no longer sold.
The DWARF II uses fixed 15 s subs, so the only levers you have are the sky you shoot from, the filter, and total time.
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 NGC 2903 from a DWARF II? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- NGC 2903 with the ZWO Seestar S50: 2 h 21 min from Bortle 6
- NGC 2903 with the ZWO Seestar S50 Pro: 2 h 34 min from Bortle 6
- NGC 2903 with the ZWO Seestar S30: 2 h 28 min from Bortle 6
- NGC 2903 with the ZWO Seestar S30 Pro: 2 h 44 min from Bortle 6
- NGC 2903 with the DwarfLab DWARF 3: 3 h 25 min from Bortle 6
- NGC 2903 with the DwarfLab DWARF mini: 2 h 20 min from Bortle 6
- NGC 2903 with the DwarfLab Draco: 1 h 56 min from Bortle 6
- NGC 2903 with the Vaonis Vespera II: 2 h 21 min from Bortle 6
- NGC 2903 with the Vaonis Vespera Pro: 5 h 16 min from Bortle 6
- NGC 2903 with the Vaonis Vespera 3: 2 h 15 min from Bortle 6
- NGC 2903 with the Vaonis Vespera Pro 2: 5 h 01 min from Bortle 6
- NGC 2903 with the Unistellar eQuinox 2: 2 h 08 min from Bortle 6
- NGC 2903 with the Unistellar Odyssey: 9 h 55 min from Bortle 6
- NGC 2903 with the Celestron Origin: 37 min from Bortle 6
- NGC 2903 with the Celestron Origin Mark II: 51 min from Bortle 6
All telescopes for the NGC 2903 · All targets for the DWARF II