How long to image the M58 with the DwarfLab DWARF II

From a Bortle 6 suburban sky, the DwarfLab DWARF II needs about 8 h 53 min (2,134 subs of 15 s) for a solid image of the M58. A quick look takes 2 h 13 min; a showpiece 36 h. Under a Bortle 3 rural sky the solid figure drops to 4 h 31 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it fills 6% of the frame’s short side.

M58 with the DwarfLab DWARF II: 15 s subs.
SkyQuick lookTarget obvious, still noisySolidClean enough to shareShowpieceSmooth faint detail, print-worthy
Bortle 1Excellent dark site1 h 01 min246 subs4 h 05 min981 subs16 h3,922 subs
Bortle 2Typical dark site1 h 03 min254 subs4 h 14 min1,016 subs17 h4,064 subs
Bortle 3Rural1 h 08 min271 subs4 h 31 min1,083 subs18 h4,332 subs
Bortle 4Rural / suburban transition1 h 18 min312 subs5 h 11 min1,246 subs21 h4,981 subs
Bortle 5Suburban1 h 34 min376 subs6 h 16 min1,503 subs25 h6,010 subs
Bortle 6Bright suburban2 h 13 min534 subs8 h 53 min2,134 subs36 h8,535 subs
Bortle 7Suburban / urban transition3 h 29 min835 subs14 h3,337 subs56 h13,347 subs
Bortle 8City5 h 25 min1,302 subs22 h5,205 subs87 h20,817 subs
Bortle 9Inner city9 h 34 min2,297 subs38 h9,188 subs150+ h36,750 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 12 h of run time. That is more than one night: over 2 nights, about 5 h 47 min each. The DWARF II’s battery is rated at about 3 h, so each night needs an external power bank. (Bortle 6, solid image; we allow 30% over the integration time.)

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How it frames

The M58 is 6′ × 5′ across. The DWARF II frames 3.19° × 1.79° at 2.99″ per pixel, so it fills 6% of the frame’s short side.

About the M58

A barred spiral in the Virgo cluster, one of the brighter members. Frame it with M59 and M60.

NGC 4579 · Galaxy in Virgo · magnitude 9.7 · 6′ × 5′ · 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 M58 with your DWARF II? Did the solid figure match?Anonymous, one tap. It is how the model gets calibrated.

Have an image of the M58 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 M58 · All targets for the DWARF II