How long to image the Spindle Galaxy with the DwarfLab DWARF II

From a Bortle 6 suburban sky, the DwarfLab DWARF II needs about 1 h 18 min (313 subs of 15 s) for a solid image of the Spindle Galaxy. A quick look takes 20 min; a showpiece 5 h 13 min. Under a Bortle 3 rural sky the solid figure drops to 45 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it fills 4% of the frame’s short side.

Spindle Galaxy with the DwarfLab DWARF II: 15 s subs.
SkyQuick lookTarget obvious, still noisySolidClean enough to shareShowpieceSmooth faint detail, print-worthy
Bortle 1Excellent dark site10 min42 subs41 min166 subs2 h 45 min661 subs
Bortle 2Typical dark site11 min43 subs42 min170 subs2 h 50 min679 subs
Bortle 3Rural11 min45 subs45 min179 subs2 h 58 min713 subs
Bortle 4Rural / suburban transition12 min50 subs50 min199 subs3 h 19 min796 subs
Bortle 5Suburban14 min58 subs58 min232 subs3 h 52 min928 subs
Bortle 6Bright suburban20 min79 subs1 h 18 min313 subs5 h 13 min1,251 subs
Bortle 7Suburban / urban transition29 min117 subs1 h 57 min467 subs7 h 47 min1,868 subs
Bortle 8City44 min177 subs2 h 56 min706 subs12 h2,824 subs
Bortle 9Inner city1 h 16 min305 subs5 h 04 min1,217 subs20 h4,865 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 1 h 42 min of run time. The DWARF II’s battery (rated about 3 h) 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.)

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How it frames

The Spindle Galaxy is 4.7′ × 1.9′ across. The DWARF II frames 3.19° × 1.79° at 2.99″ per pixel, so it fills 4% of the frame’s short side.

About the Spindle Galaxy

An edge-on lenticular with a thin dust lane. Small, but its surface brightness is decent.

M102, NGC 5866 · Galaxy in Draco · magnitude 9.9 · 4.7′ × 1.9′ · 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 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.

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Imaged the Spindle Galaxy with your DWARF II? Did the solid figure match?Anonymous, one tap. It is how the model gets calibrated.

Have an image of the Spindle Galaxy from a DWARF II? Email it with your total time and sky to [email protected] and it goes here, credited.

Same target, other telescopes

All telescopes for the Spindle Galaxy · All targets for the DWARF II