How long to image the Cigar Galaxy with the Vaonis Vespera II

From a Bortle 6 suburban sky, the Vaonis Vespera II needs about 35 min (208 subs of 10 s) for a solid image of the Cigar Galaxy. A quick look takes 9 min; a showpiece 2 h 18 min. Under a Bortle 3 rural sky the solid figure drops to 15 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 13% of the frame’s short side.

Cigar Galaxy with the Vaonis Vespera II: 10 s subs.
SkyQuick lookTarget obvious, still noisySolidClean enough to shareShowpieceSmooth faint detail, print-worthy
Bortle 1Excellent dark site3 min20 subs13 min79 subs52 min315 subs
Bortle 2Typical dark site3 min21 subs14 min83 subs55 min331 subs
Bortle 3Rural4 min23 subs15 min91 subs1 h361 subs
Bortle 4Rural / suburban transition5 min28 subs18 min109 subs1 h 12 min433 subs
Bortle 5Suburban6 min35 subs23 min137 subs1 h 31 min548 subs
Bortle 6Bright suburban9 min52 subs35 min208 subs2 h 18 min830 subs
Bortle 7Suburban / urban transition14 min86 subs57 min342 subs3 h 48 min1,367 subs
Bortle 8City23 min138 subs1 h 32 min550 subs6 h 07 min2,200 subs
Bortle 9Inner city41 min249 subs2 h 46 min995 subs11 h3,978 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 45 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, and 30% off the battery for a February night.)

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How it frames

The Cigar Galaxy is 11′ × 4′ across. The Vespera II frames 2.55° × 1.44° at 2.39″ per pixel, so it fills 13% 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 s15 min91 subs23 min137 subs57 min342 subs
20 s13 min40 subs21 min63 subs55 min166 subs
30 s15 min30 subs20 min41 subs54 min109 subs

About the Cigar Galaxy

An edge-on starburst galaxy with red hydrogen jets bursting from its core. Dual-band pulls the jets out of the glare.

M82, NGC 3034 · Galaxy in Ursa Major · magnitude 8.4 · 11′ × 4′ · best in Jan, Feb, Mar. 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 Cigar Galaxy with your Vespera II? Did the solid figure match?Anonymous, one tap. It is how the model gets calibrated.

Have an image of the Cigar Galaxy 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 Cigar Galaxy · All targets for the Vespera II