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

From a Bortle 6 suburban sky, the DwarfLab DWARF II needs about 2 h 39 min (636 subs of 15 s) for a solid image of the Sombrero Galaxy. A quick look takes 40 min; a showpiece 11 h. Under a Bortle 3 rural sky the solid figure drops to 1 h 24 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it fills 8% of the frame’s short side.

Sombrero Galaxy with the DwarfLab DWARF II: 15 s subs.
SkyQuick lookTarget obvious, still noisySolidClean enough to shareShowpieceSmooth faint detail, print-worthy
Bortle 1Excellent dark site19 min77 subs1 h 17 min308 subs5 h 08 min1,232 subs
Bortle 2Typical dark site20 min80 subs1 h 20 min319 subs5 h 18 min1,273 subs
Bortle 3Rural21 min85 subs1 h 24 min338 subs5 h 37 min1,349 subs
Bortle 4Rural / suburban transition24 min96 subs1 h 36 min384 subs6 h 23 min1,533 subs
Bortle 5Suburban29 min115 subs1 h 54 min457 subs7 h 36 min1,825 subs
Bortle 6Bright suburban40 min159 subs2 h 39 min636 subs11 h2,541 subs
Bortle 7Suburban / urban transition1 h 01 min245 subs4 h 04 min977 subs16 h3,905 subs
Bortle 8City1 h 34 min377 subs6 h 16 min1,506 subs25 h6,023 subs
Bortle 9Inner city2 h 45 min659 subs11 h2,636 subs44 h10,541 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 3 h 26 min of run time. The DWARF II’s battery is rated at about 3 h, so the session needs an external power bank. (Bortle 6, solid image; we allow 30% over the integration time.)

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How it frames

The Sombrero Galaxy is 9′ × 4′ across. The DWARF II frames 3.19° × 1.79° at 2.99″ per pixel, so it fills 8% of the frame’s short side.

About the Sombrero Galaxy

The bright bulge and knife-edge dust lane are obvious within an hour. Low from northern Europe, so catch it near the meridian.

M104, NGC 4594 · Galaxy in Virgo · magnitude 8.0 · 9′ × 4′ · 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 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 Sombrero 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 Sombrero 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 Sombrero Galaxy · All targets for the DWARF II