How long should I image the Ghost of Cassiopeia with the Vespera Pro from a Bortle 6 sky?

About 6 h 21 min of total integration for a solid image, or 25 h for a showpiece. A quick look takes 1 h 35 min.

How many subs is that on the Vespera Pro?

At the default 10 s sub length, 2,288 subs for a solid image from Bortle 6 and 959 from Bortle 3.

Does a dual-band filter help on the Ghost of Cassiopeia?

Yes. It is an emission-line object; from Bortle 6 the filter cuts the solid-image time from 6 h 21 min to 4 h 35 min.

How long to image the Ghost of Cassiopeia with the Vaonis Vespera Pro

From a Bortle 6 suburban sky, the Vaonis Vespera Pro needs about 6 h 21 min (2,288 subs of 10 s) for a solid image of the Ghost of Cassiopeia. A quick look takes 1 h 35 min; a showpiece 25 h. Under a Bortle 3 rural sky the solid figure drops to 2 h 40 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 10% of the frame’s short side.

Ghost of Cassiopeia 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	35 min208 subs	2 h 18 min829 subs	9 h 12 min3,315 subs
Bortle 2Typical dark site	36 min219 subs	2 h 26 min874 subs	9 h 42 min3,494 subs
Bortle 3Rural	40 min240 subs	2 h 40 min959 subs	11 h3,833 subs
Bortle 4Rural / suburban transition	48 min291 subs	3 h 14 min1,164 subs	13 h4,655 subs
Bortle 5Suburban	1 h 02 min373 subs	4 h 08 min1,489 subs	17 h5,956 subs
Bortle 6Bright suburban	1 h 35 min572 subs	6 h 21 min2,288 subs	25 h9,150 subs
Bortle 7Suburban / urban transition	2 h 39 min953 subs	11 h3,809 subs	42 h15,235 subs
Bortle 8City	4 h 17 min1,543 subs	17 h6,171 subs	69 h24,684 subs
Bortle 9Inner city	7 h 47 min2,803 subs	31 h11,209 subs	120+ h44,835 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 8 h 16 min of run time. That is more than one night: over 2 nights, about 4 h 08 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 Ghost of Cassiopeia is 10′ × 3′ across. The Vespera Pro frames 1.62° × 1.62° at 1.65″ per pixel, so it fills 10% 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	2 h 40 min959 subs	4 h 08 min1,489 subs	11 h3,809 subs
20 s	2 h 12 min396 subs	3 h 40 min661 subs	10 h1,821 subs
30 s	2 h 03 min246 subs	3 h 31 min422 subs	9 h 58 min1,196 subs

With and without the dual-band filter

Solid quality, default sub length.
Filter	Bortle 3	Bortle 5	Bortle 7
No filter	2 h 40 min959 subs	4 h 08 min1,489 subs	11 h3,809 subs
dual-band (Dual Band filter), clip-on	3 h 27 min1,244 subs	3 h 54 min1,407 subs	5 h 53 min2,117 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 Ghost of Cassiopeia

A small emission and reflection wisp being eroded by the star Gamma Cassiopeiae. Keep the bright star's glare under control.

IC 63 · Emission nebula in Cassiopeia · magnitude 10.0 · 10′ × 3′ · 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 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 Ghost of Cassiopeia with your Vespera Pro? Did the solid figure match?Anonymous, one tap. It is how the model gets calibrated.

Have an image of the Ghost of Cassiopeia 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 Ghost of Cassiopeia · All targets for the Vespera Pro