How long to image the M2 with the Unistellar eQuinox 2

From a Bortle 6 suburban sky, the Unistellar eQuinox 2 needs about 9 min (134 subs of 4 s) for a solid image of the M2. A quick look takes 2 min; a showpiece 36 min. Under a Bortle 3 rural sky the solid figure drops to 6 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it fills 47% of the frame’s short side.

M2 with the Unistellar eQuinox 2: 4 s subs.
SkyQuick lookTarget obvious, still noisySolidClean enough to shareShowpieceSmooth faint detail, print-worthy
Bortle 1Excellent dark site1 min20 subs5 min80 subs21 min318 subs
Bortle 2Typical dark site1 min21 subs5 min81 subs22 min324 subs
Bortle 3Rural1 min22 subs6 min85 subs22 min337 subs
Bortle 4Rural / suburban transition2 min23 subs6 min92 subs24 min368 subs
Bortle 5Suburban2 min26 subs7 min104 subs28 min416 subs
Bortle 6Bright suburban2 min34 subs9 min134 subs36 min536 subs
Bortle 7Suburban / urban transition3 min48 subs13 min191 subs51 min764 subs
Bortle 8City5 min70 subs19 min280 subs1 h 14 min1,117 subs
Bortle 9Inner city8 min117 subs31 min468 subs2 h 05 min1,871 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 12 min of run time. The eQuinox 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 M2 is 16′ across. The eQuinox 2 frames 0.76° × 0.57° at 1.33″ per pixel, so it fills 47% of the frame’s short side.

About the M2

A rich, compact globular in Aquarius. Resolves well at the edges even in a short stack.

NGC 7089 · Globular cluster in Aquarius · magnitude 6.5 · 16′ · best in Jul, Aug, Sep. 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 Unistellar eQuinox 2

A 114 mm Newtonian with five times the light grasp of a 50 mm refractor. Fixed 4 s subs put it in read-noise territory under dark skies, but the aperture carries it. The published field is 45.6′ × 34.2′, a crop of the sensor.

Fixed 4 s subs in Enhanced Vision; they cannot be changed. No built-in filter. Unistellar sells only a solar filter and says a third-party filter is at your own risk and voids the warranty.

The eQuinox 2 uses fixed 4 s subs, so the only levers you have are the sky you shoot from, the filter, and total time.

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 M2 with your eQuinox 2? Did the solid figure match?Anonymous, one tap. It is how the model gets calibrated.

Have an image of the M2 from a eQuinox 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 M2 · All targets for the eQuinox 2