How long to image the M49 with the Vaonis Vespera II

From a Bortle 6 suburban sky, the Vaonis Vespera II needs about 1 h 09 min (416 subs of 10 s) for a solid image of the M49. A quick look takes 17 min; a showpiece 4 h 37 min. Under a Bortle 3 rural sky the solid figure drops to 28 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.

M49 with the Vaonis Vespera II: 10 s subs.
SkyQuick lookTarget obvious, still noisySolidClean enough to shareShowpieceSmooth faint detail, print-worthy
Bortle 1Excellent dark site6 min37 subs24 min146 subs1 h 37 min584 subs
Bortle 2Typical dark site6 min39 subs26 min155 subs1 h 43 min617 subs
Bortle 3Rural7 min43 subs28 min170 subs1 h 53 min679 subs
Bortle 4Rural / suburban transition9 min52 subs35 min208 subs2 h 18 min831 subs
Bortle 5Suburban11 min67 subs45 min268 subs2 h 58 min1,071 subs
Bortle 6Bright suburban17 min104 subs1 h 09 min416 subs4 h 37 min1,661 subs
Bortle 7Suburban / urban transition29 min174 subs1 h 56 min696 subs7 h 44 min2,784 subs
Bortle 8City47 min283 subs3 h 09 min1,132 subs13 h4,528 subs
Bortle 9Inner city1 h 26 min516 subs5 h 44 min2,062 subs23 h8,248 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 1 h 30 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 M49 is 10′ × 8′ across. The Vespera II frames 2.55° × 1.44° at 2.39″ 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, no EQ mode. Time for a solid image by sub length:

Sub lengthBortle 3Bortle 5Bortle 7
10 s28 min170 subs45 min268 subs1 h 56 min696 subs
20 s24 min74 subs41 min123 subs1 h 52 min337 subs
30 s23 min47 subs40 min80 subs1 h 51 min222 subs

About the M49

The brightest galaxy in the Virgo cluster, a featureless elliptical. Comes quickly but shows no structure.

NGC 4472 · Galaxy in Virgo · magnitude 8.4 · 10′ × 8′ · 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 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 M49 with your Vespera II? Did the solid figure match?Anonymous, one tap. It is how the model gets calibrated.

Have an image of the M49 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 M49 · All targets for the Vespera II