How long should I image the Heart Nebula with the DWARF 3 from a Bortle 6 sky?

About 3 h 27 min of total integration for a solid image, or 14 h for a showpiece. A quick look takes 52 min.

How many subs is that on the DWARF 3?

At the default 15 s sub length, 829 subs for a solid image from Bortle 6 and 496 from Bortle 3.

Does a dual-band filter help on the Heart Nebula?

Yes. It is an emission-line object; from Bortle 6 the filter cuts the solid-image time from 6 h 41 min to 3 h 27 min.

How long to image the Heart Nebula with the DwarfLab DWARF 3

From a Bortle 6 suburban sky, the DwarfLab DWARF 3 needs about 3 h 27 min (829 subs of 15 s with the built-in dual-band filter) for a solid image of the Heart Nebula. A quick look takes 52 min; a showpiece 14 h. Under a Bortle 3 rural sky the solid figure drops to 2 h 04 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it fills 61% of the frame’s short side.

Heart Nebula with the DwarfLab DWARF 3: 15 s subs with the built-in dual-band filter.
Sky	Quick lookTarget obvious, still noisy	SolidClean enough to share	ShowpieceSmooth faint detail, print-worthy
Bortle 1Excellent dark site	29 min116 subs	1 h 56 min463 subs	7 h 43 min1,851 subs
Bortle 2Typical dark site	30 min119 subs	1 h 58 min474 subs	7 h 54 min1,896 subs
Bortle 3Rural	31 min124 subs	2 h 04 min496 subs	8 h 15 min1,982 subs
Bortle 4Rural / suburban transition	34 min137 subs	2 h 17 min547 subs	9 h 07 min2,188 subs
Bortle 5Suburban	39 min158 subs	2 h 37 min629 subs	10 h2,515 subs
Bortle 6Bright suburban	52 min208 subs	3 h 27 min829 subs	14 h3,316 subs
Bortle 7Suburban / urban transition	1 h 16 min303 subs	5 h 03 min1,211 subs	20 h4,844 subs
Bortle 8City	1 h 53 min452 subs	7 h 31 min1,805 subs	30 h7,217 subs
Bortle 9Inner city	3 h 12 min768 subs	13 h3,069 subs	51 h12,276 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 4 h 29 min of run time. The DWARF 3’s battery is rated at about 5 h 30 min, less near freezing, so the session 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.)

USB-C PD power bank 20000mAh 18W18 W PD input and it runs while charging; needs a C-to-C cable for PD.
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red LED head torchRed light keeps your night vision; white light costs you twenty minutes of dark adaptation every time.
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How it frames

The Heart Nebula is 60′ across. The DWARF 3 frames 2.93° × 1.65° at 2.75″ per pixel, so it fills 61% of the frame’s short side.

Longer subs

Auto mode caps subs at 15 s; 30 s and longer need EQ mode, and 60 s is the ceiling on the tele camera. Time for a solid image by sub length:

Sub length	Bortle 3	Bortle 5	Bortle 7
15 s	2 h 04 min496 subs	2 h 37 min629 subs	5 h 03 min1,211 subs
30 s	1 h 45 min210 subs	2 h 18 min276 subs	4 h 43 min567 subs
60 s	1 h 35 min95 subs	2 h 08 min129 subs	4 h 34 min274 subs

With and without the dual-band filter

Solid quality, default sub length.
Filter	Bortle 3	Bortle 5	Bortle 7
Astro (no light-pollution filter)	2 h 08 min514 subs	3 h 57 min949 subs	12 h2,852 subs
dual-band	2 h 04 min496 subs	2 h 37 min629 subs	5 h 03 min1,211 subs

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 3

Small pixels on a 35 mm f/4.3 lens give a sharper image than its aperture suggests, and EQ mode with 60 s subs makes it the read-noise winner in dark skies.

Auto mode caps subs at 15 s; 30 s and longer need EQ mode, and 60 s is the ceiling on the tele camera. Three built-in filters: VIS, Astro (430 to 690 nm) and dual-band Hα 656 nm / OIII 501 nm.

Longer subs matter most under dark skies, where read noise rather than skyglow sets the floor. From a city the difference between 15 s and 60 s subs is small; from a rural site it can halve the total time, especially with a dual-band filter in place.

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 3? 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 3? 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 3