How long to image the M9 with the Vaonis Vespera Pro 2

From a Bortle 6 suburban sky, the Vaonis Vespera Pro 2 needs about 1 h 12 min (431 subs of 10 s) for a solid image of the M9. A quick look takes 18 min; a showpiece 4 h 47 min. Under a Bortle 3 rural sky the solid figure drops to 33 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 12% of the frame’s short side.

M9 with the Vaonis Vespera Pro 2: 10 s subs.
SkyQuick lookTarget obvious, still noisySolidClean enough to shareShowpieceSmooth faint detail, print-worthy
Bortle 1Excellent dark site7 min44 subs29 min176 subs1 h 57 min702 subs
Bortle 2Typical dark site8 min46 subs31 min184 subs2 h 02 min733 subs
Bortle 3Rural8 min50 subs33 min199 subs2 h 12 min793 subs
Bortle 4Rural / suburban transition10 min59 subs39 min234 subs2 h 36 min936 subs
Bortle 5Suburban12 min73 subs48 min291 subs3 h 14 min1,164 subs
Bortle 6Bright suburban18 min108 subs1 h 12 min431 subs4 h 47 min1,722 subs
Bortle 7Suburban / urban transition29 min175 subs1 h 56 min697 subs7 h 44 min2,787 subs
Bortle 8City46 min278 subs3 h 05 min1,110 subs12 h4,439 subs
Bortle 9Inner city1 h 23 min498 subs5 h 32 min1,991 subs22 h7,964 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 1 h 33 min of run time. The Vespera Pro 2’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.)

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How it frames

The M9 is 12′ across. The Vespera Pro 2 frames 1.65° × 1.65° at 1.68″ per pixel, so it fills 12% 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; CovalENS mosaic gives 3.2° × 3.2° at 50 MP. Time for a solid image by sub length:

Sub lengthBortle 3Bortle 5Bortle 7
10 s33 min199 subs48 min291 subs1 h 56 min697 subs
20 s28 min85 subs44 min132 subs1 h 51 min335 subs
30 s27 min54 subs42 min85 subs1 h 50 min220 subs

About the M9

A small globular near the galactic centre, slightly dimmed by dust. Compact and easy.

NGC 6333 · Globular cluster in Ophiuchus · magnitude 7.7 · 12′ · best in May, Jun, Jul. Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.

Globular clusters are point sources packed tight, so they come quickly: the core resolves into stars within a handful of minutes on any smart scope. More time deepens the halo and pulls in the faint outer members. Use short subs so the core does not saturate into a white blob, and no filter.

About the Vaonis Vespera Pro 2

The square-sensor 2026 Vespera with 2 µm pixels. Sharper than the Vespera 3 on small targets and correspondingly slower per pixel; the 12.5 MP square frame suits galaxies and planetaries.

10 s subs by default; Expert Mode manual targets allow 1 to 30 s. Alt-azimuth only; CovalENS mosaic gives 3.2° × 3.2° at 50 MP. 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 M9 with your Vespera Pro 2? Did the solid figure match?Anonymous, one tap. It is how the model gets calibrated.

Have an image of the M9 from a Vespera Pro 2? Email it with your total time and sky to [email protected] and it goes here, credited.

Same target, other telescopes

All telescopes for the M9 · All targets for the Vespera Pro 2