How long to image the M69 with the Vaonis Vespera II

From a Bortle 6 suburban sky, the Vaonis Vespera II needs about 17 min (101 subs of 10 s) for a solid image of the M69. A quick look takes 4 min; a showpiece 1 h 07 min. Under a Bortle 3 rural sky the solid figure drops to 8 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 11% of the frame’s short side.

M69 with the Vaonis Vespera II: 10 s subs.
SkyQuick lookTarget obvious, still noisySolidClean enough to shareShowpieceSmooth faint detail, print-worthy
Bortle 1Excellent dark site2 min11 subs7 min44 subs29 min175 subs
Bortle 2Typical dark site2 min12 subs8 min46 subs30 min182 subs
Bortle 3Rural2 min13 subs8 min49 subs32 min195 subs
Bortle 4Rural / suburban transition2 min15 subs9 min57 subs38 min227 subs
Bortle 5Suburban3 min18 subs12 min70 subs46 min278 subs
Bortle 6Bright suburban4 min26 subs17 min101 subs1 h 07 min404 subs
Bortle 7Suburban / urban transition7 min41 subs27 min161 subs1 h 47 min643 subs
Bortle 8City11 min64 subs42 min254 subs2 h 49 min1,013 subs
Bortle 9Inner city19 min113 subs1 h 15 min451 subs5 h 01 min1,804 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 22 min of run time. The Vespera II’s battery (rated about 4 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 M69 is 9.8′ across. The Vespera II frames 2.55° × 1.44° at 2.39″ per pixel, so it fills 11% 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 lengthBortle 3Bortle 5Bortle 7
10 s8 min49 subs12 min70 subs27 min161 subs
20 s10 min30 subs11 min33 subs26 min78 subs
30 s15 min30 subs15 min30 subs26 min52 subs

About the M69

A small, metal-rich globular near the Sagittarius teapot's base. Low from the north.

NGC 6637 · Globular cluster in Sagittarius · magnitude 7.6 · 9.8′ · best in Jun, Jul, Aug. 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 II

A 50 mm quadruplet on an 8 MP sensor with Vaonis’s mosaic mode for wide fields. Same optics class as the Seestar S50, four times the pixels.

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; the app detects which is fitted.

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 M69 with your Vespera II? Did the solid figure match?Anonymous, one tap. It is how the model gets calibrated.

Have an image of the M69 from a Vespera II? Email it with your total time and sky to [email protected] and it goes here, credited.

Same target, other telescopes

All telescopes for the M69 · All targets for the Vespera II