How long should I image the Sombrero Galaxy with the Vespera Pro from a Bortle 6 sky?

About 1 h 45 min of total integration for a solid image, or 6 h 59 min for a showpiece. A quick look takes 26 min.

How many subs is that on the Vespera Pro?

At the default 10 s sub length, 629 subs for a solid image from Bortle 6 and 291 from Bortle 3.

Does a dual-band filter help on the Sombrero Galaxy?

No. The Sombrero Galaxy is a broadband target and a dual-band filter blocks most of its light. Shoot without a filter.

How long to image the Sombrero Galaxy with the Vaonis Vespera Pro

From a Bortle 6 suburban sky, the Vaonis Vespera Pro needs about 1 h 45 min (629 subs of 10 s) for a solid image of the Sombrero Galaxy. A quick look takes 26 min; a showpiece 6 h 59 min. Under a Bortle 3 rural sky the solid figure drops to 48 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 9% of the frame’s short side.

Sombrero Galaxy 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	11 min65 subs	43 min258 subs	2 h 52 min1,031 subs
Bortle 2Typical dark site	11 min68 subs	45 min269 subs	2 h 59 min1,076 subs
Bortle 3Rural	12 min73 subs	48 min291 subs	3 h 14 min1,162 subs
Bortle 4Rural / suburban transition	14 min86 subs	57 min343 subs	3 h 49 min1,372 subs
Bortle 5Suburban	18 min107 subs	1 h 11 min426 subs	4 h 44 min1,703 subs
Bortle 6Bright suburban	26 min158 subs	1 h 45 min629 subs	6 h 59 min2,516 subs
Bortle 7Suburban / urban transition	42 min255 subs	2 h 49 min1,017 subs	11 h4,065 subs
Bortle 8City	1 h 07 min405 subs	4 h 30 min1,618 subs	18 h6,470 subs
Bortle 9Inner city	2 h 01 min725 subs	8 h 03 min2,900 subs	32 h11,599 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 2 h 16 min of run time. The Vespera Pro’s battery (rated about 11 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 20000mAh 30WExtends the 11 h battery; 30 W PD per Vaonis.
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How it frames

The Sombrero Galaxy is 9′ × 4′ across. The Vespera Pro frames 1.62° × 1.62° at 1.65″ per pixel, so it fills 9% 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	48 min291 subs	1 h 11 min426 subs	2 h 49 min1,017 subs
20 s	41 min124 subs	1 h 04 min192 subs	2 h 42 min487 subs
30 s	39 min78 subs	1 h 01 min123 subs	2 h 40 min320 subs

About the Sombrero Galaxy

The bright bulge and knife-edge dust lane are obvious within an hour. Low from northern Europe, so catch it near the meridian.

M104, NGC 4594 · Galaxy in Virgo · magnitude 8.0 · 9′ × 4′ · best in Mar, Apr, May. Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.

Galaxies are broadband targets: their light is mostly starlight spread across the spectrum, so a dual-band filter throws most of it away and makes things slower, not faster. Shoot without a filter (or with a plain UV/IR cut) and rely on total time and a dark sky. The core of a galaxy is usually many times brighter than its outer disc, so a short stack shows the nucleus long before the arms; the figures here are for the arms and disc, not the core.

Field rotation in Alt-Az mode crops the edges of the stack over a long session, so on a big galaxy re-centre now and then or use EQ mode where your scope supports it.

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 Sombrero Galaxy with your Vespera Pro? Did the solid figure match?Anonymous, one tap. It is how the model gets calibrated.

Have an image of the Sombrero Galaxy 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 Sombrero Galaxy · All targets for the Vespera Pro