How long should I image the Bubble Nebula with the Vespera Pro from a Bortle 6 sky?

About 10 h of total integration for a solid image, or 41 h for a showpiece. A quick look takes 2 h 35 min.

How many subs is that on the Vespera Pro?

At the default 10 s sub length, 3,727 subs for a solid image from Bortle 6 and 1,501 from Bortle 3.

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

Yes. It is an emission-line object; from Bortle 6 the filter cuts the solid-image time from 10 h to 7 h 16 min.

How long to image the Bubble Nebula with the Vaonis Vespera Pro

From a Bortle 6 suburban sky, the Vaonis Vespera Pro needs about 10 h (3,727 subs of 10 s) for a solid image of the Bubble Nebula. A quick look takes 2 h 35 min; a showpiece 41 h. Under a Bortle 3 rural sky the solid figure drops to 4 h 10 min. At Bortle 6 the limit is skyglow, so a darker site or a filter helps more than longer subs. In this scope's field it fills 15% of the frame’s short side.

Bubble Nebula with the Vaonis Vespera Pro: 10 s subs.
Sky	Quick lookTarget obvious, still noisy	SolidClean enough to share	ShowpieceSmooth faint detail, print-worthy
Bortle 1Excellent dark site	53 min321 subs	3 h 34 min1,284 subs	14 h5,136 subs
Bortle 2Typical dark site	57 min340 subs	3 h 46 min1,359 subs	15 h5,436 subs
Bortle 3Rural	1 h 03 min376 subs	4 h 10 min1,501 subs	17 h6,004 subs
Bortle 4Rural / suburban transition	1 h 17 min462 subs	5 h 07 min1,845 subs	20 h7,379 subs
Bortle 5Suburban	1 h 40 min598 subs	6 h 38 min2,390 subs	27 h9,559 subs
Bortle 6Bright suburban	2 h 35 min932 subs	10 h3,727 subs	41 h14,907 subs
Bortle 7Suburban / urban transition	4 h 21 min1,569 subs	17 h6,275 subs	70 h25,097 subs
Bortle 8City	7 h 06 min2,558 subs	28 h10,230 subs	110+ h40,920 subs
Bortle 9Inner city	13 h4,667 subs	52 h18,666 subs	210+ h74,664 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 13 h of run time. That is more than one night: over 2 nights, about 6 h 44 min each. The Vespera Pro’s battery (rated about 11 h) should cover each night; a power bank still keeps the phone running the app alive. (Bortle 6, solid image; we allow 30% over the integration time.)

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How it frames

The Bubble Nebula is 15′ × 8′ across. The Vespera Pro frames 1.62° × 1.62° at 1.65″ per pixel, so it fills 15% of the frame’s short side.

Longer subs

10 s subs by default; Expert Mode manual targets allow 1 to 30 s. Alt-azimuth only, no EQ mode. Time for a solid image by sub length:

Sub length	Bortle 3	Bortle 5	Bortle 7
10 s	4 h 10 min1,501 subs	6 h 38 min2,390 subs	17 h6,275 subs
20 s	3 h 23 min611 subs	5 h 52 min1,055 subs	17 h2,998 subs
30 s	3 h 08 min376 subs	5 h 36 min673 subs	16 h1,967 subs

With and without the dual-band filter

Solid quality, default sub length.
Filter	Bortle 3	Bortle 5	Bortle 7
No filter	4 h 10 min1,501 subs	6 h 38 min2,390 subs	17 h6,275 subs
dual-band (Dual Band filter), clip-on	5 h 22 min1,935 subs	6 h 08 min2,207 subs	9 h 26 min3,396 subs

The Vespera Pro has no built-in dual-band filter. Optional clip-on Vaonis filters: dual-band, light-pollution (CLS) and solar. On an emission target like this it is the single biggest upgrade you can make.

About the Bubble Nebula

A wind-blown bubble in a larger hydrogen cloud beside M52. Small; the bubble itself needs a scope with reach.

NGC 7635, Caldwell 11 · Emission nebula in Cassiopeia · magnitude 10.0 · 15′ × 8′ · best in Aug, Sep, Oct. 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 Vaonis Vespera Pro

The square-sensor Vespera with 2 µm pixels. Higher resolution than the II, and correspondingly slower per pixel: expect around double the time for the same per-pixel SNR. Run-out in 2026 and replaced by the Vespera Pro 2.

10 s subs by default; Expert Mode manual targets allow 1 to 30 s. Alt-azimuth only, no EQ mode. Optional clip-on Vaonis filters: dual-band, light-pollution (CLS) and solar.

Longer subs matter most under dark skies, where read noise rather than skyglow sets the floor. From a city the difference between 10 s and 30 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 Bubble Nebula with your Vespera Pro? Did the solid figure match?Anonymous, one tap. It is how the model gets calibrated.

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

Same target, other telescopes

All telescopes for the Bubble Nebula · All targets for the Vespera Pro