How long should I image the Pacman Nebula with the Draco from a Bortle 6 sky?

About 1 h 20 min of total integration for a solid image, or 5 h 20 min for a showpiece. A quick look takes 20 min.

How many subs is that on the Draco?

At the default 30 s sub length, 160 subs for a solid image from Bortle 6 and 109 from Bortle 3.

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

Yes. It is an emission-line object; from Bortle 6 the filter cuts the solid-image time from 2 h 13 min to 1 h 20 min.

How long to image the Pacman Nebula with the DwarfLab Draco

From a Bortle 6 suburban sky, the DwarfLab Draco needs about 1 h 20 min (160 subs of 30 s with the built-in dual-narrowband (Hα + OIII) filter) for a solid image of the Pacman Nebula. A quick look takes 20 min; a showpiece 5 h 20 min. Under a Bortle 3 rural sky the solid figure drops to 54 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it fills 47% of the frame’s short side.

Pacman Nebula with the DwarfLab Draco: 30 s subs with the built-in dual-narrowband (Hα + OIII) filter.
Sky	Quick lookTarget obvious, still noisy	SolidClean enough to share	ShowpieceSmooth faint detail, print-worthy
Bortle 1Excellent dark site	13 min26 subs	51 min103 subs	3 h 26 min412 subs
Bortle 2Typical dark site	13 min27 subs	52 min105 subs	3 h 29 min419 subs
Bortle 3Rural	14 min28 subs	54 min109 subs	3 h 36 min433 subs
Bortle 4Rural / suburban transition	15 min30 subs	58 min117 subs	3 h 52 min465 subs
Bortle 5Suburban	16 min33 subs	1 h 04 min129 subs	4 h 17 min515 subs
Bortle 6Bright suburban	20 min40 subs	1 h 20 min160 subs	5 h 20 min640 subs
Bortle 7Suburban / urban transition	27 min55 subs	1 h 50 min220 subs	7 h 18 min877 subs
Bortle 8City	39 min78 subs	2 h 36 min312 subs	10 h1,245 subs
Bortle 9Inner city	1 h 03 min127 subs	4 h 14 min508 subs	17 h2,031 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 1 h 44 min of run time. The Draco’s battery (rated about 5 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.)

USB-C PD power bank 20000mAhRated 5 h on its 10,000 mAh battery. DwarfLab has not published the charging input, so check PD support before relying on it mid-session.
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How it frames

The Pacman Nebula is 35′ × 30′ across. The Draco frames 1.66° × 1.24° at 1.46″ per pixel, so it fills 47% of the frame’s short side.

Longer subs

Auto Mode picks the exposure; Pro Mode allows up to 300 s, held by built-in guiding and field derotation. The 30 s default here is our assumption. Time for a solid image by sub length:

Sub length	Bortle 3	Bortle 5	Bortle 7
30 s	54 min109 subs	1 h 04 min129 subs	1 h 50 min220 subs
60 s	39 min40 subs	50 min50 subs	1 h 35 min96 subs
120 s	1 h30 subs	1 h30 subs	1 h 28 min44 subs
300 s	2 h 30 min30 subs	2 h 30 min30 subs	2 h 30 min30 subs

With and without the dual-band filter

Solid quality, default sub length.
Filter	Bortle 3	Bortle 5	Bortle 7
No filter	48 min97 subs	1 h 22 min164 subs	3 h 50 min460 subs
dual-narrowband (Hα + OIII)	54 min109 subs	1 h 04 min129 subs	1 h 50 min220 subs

About the Pacman Nebula

A bright emission nebula with a dark lane biting into it. Compact, bright, and excellent with a dual-band filter from suburban skies.

NGC 281 · Emission nebula in Cassiopeia · magnitude 7.4 · 35′ × 30′ · best in Sep, Oct, Nov. 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 Draco

DwarfLab’s big scope: 90 mm of folded f/3.8 optics, the most aperture of any Seestar or DWARF, a narrow 13 nm dual-band filter and 300 s subs with built-in guiding. A small-target scope; big nebulae need its mosaic mode.

Auto Mode picks the exposure; Pro Mode allows up to 300 s, held by built-in guiding and field derotation. The 30 s default here is our assumption. Built-in Hα + OIII dual-narrowband filter, 13 nm per line; the SHO Edition adds an SII option.

Longer subs matter most under dark skies, where read noise rather than skyglow sets the floor. From a city the difference between 30 s and 300 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 Pacman Nebula with your Draco? Did the solid figure match?Anonymous, one tap. It is how the model gets calibrated.

Have an image of the Pacman Nebula from a Draco? Email it with your total time and sky to [email protected] and it goes here, credited.

Same target, other telescopes

All telescopes for the Pacman Nebula · All targets for the Draco