How long to image the Heart Nebula with the DwarfLab DWARF II

From a Bortle 6 suburban sky, the DwarfLab DWARF II needs about 16 h (3,817 subs of 15 s) for a solid image of the Heart Nebula. A quick look takes 3 h 59 min; a showpiece 64 h. Under a Bortle 3 rural sky the solid figure drops to 7 h 44 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it fills 56% of the frame’s short side.

Heart Nebula 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 44 min417 subs6 h 56 min1,665 subs28 h6,660 subs
Bortle 2Typical dark site1 h 48 min433 subs7 h 13 min1,731 subs29 h6,924 subs
Bortle 3Rural1 h 56 min464 subs7 h 44 min1,856 subs31 h7,424 subs
Bortle 4Rural / suburban transition2 h 15 min540 subs9 h2,159 subs36 h8,635 subs
Bortle 5Suburban2 h 45 min660 subs11 h2,639 subs44 h10,555 subs
Bortle 6Bright suburban3 h 59 min955 subs16 h3,817 subs64 h15,266 subs
Bortle 7Suburban / urban transition6 h 19 min1,516 subs25 h6,061 subs100+ h24,242 subs
Bortle 8City9 h 57 min2,387 subs40 h9,545 subs160+ h38,178 subs
Bortle 9Inner city18 h4,244 subs71 h16,975 subs280+ h67,899 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 21 h of run time. That is more than one night: over 3 nights, about 6 h 53 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 November night.)

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How it frames

The Heart Nebula is 60′ across. The DWARF II frames 3.19° × 1.79° at 2.99″ per pixel, so it fills 56% of the frame’s short side.

Filters

The Heart Nebula is an emission target, where a dual-band filter would normally cut the time several-fold from a lit sky, but the DWARF II has no dual-band option: Two built-in filters, VIS and Astro (IR-pass); no dual-band. The optional UHC filter is no longer sold. The figures above are for the Astro position, and a darker sky is the lever that remains.

About the Heart Nebula

A degree-wide hydrogen cloud shaped like a heart, with the bright Melotte 15 cluster and pillars at its centre. Dual-band, and a wide field or mosaic.

IC 1805, Sh2-190 · Emission nebula in Cassiopeia · magnitude 6.5 · 60′ · best in Oct, Nov, Dec. Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.

Emission nebulae glow in a few narrow lines, mostly hydrogen-alpha (deep red) and doubly ionised oxygen (teal). A dual-band filter passes those lines and blocks most skyglow, which is why it cuts the time needed from a suburban sky so dramatically. Use it. From a genuinely dark site the gain is smaller because there is less skyglow to block, and read noise becomes the limit, which is where longer subs (EQ mode, or Expert Mode on a Vespera) earn their keep.

Stars lose colour through a dual-band filter; a short broadband stack blended in fixes that if you care.

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

Have an image of the Heart Nebula 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 Heart Nebula · All targets for the DWARF II