How long to image the NGC 663 with the Unistellar eQuinox 2

From a Bortle 6 suburban sky, the Unistellar eQuinox 2 needs about 2 min (32 subs of 4 s) for a solid image of the NGC 663. A quick look takes < 1 min; a showpiece 8 min. Under a Bortle 3 rural sky the solid figure drops to 2 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.

NGC 663 with the Unistellar eQuinox 2: 4 s subs.
SkyQuick lookTarget obvious, still noisySolidClean enough to shareShowpieceSmooth faint detail, print-worthy
Bortle 1Excellent dark site< 1 min10 subs2 min30 subs6 min90 subs
Bortle 2Typical dark site< 1 min10 subs2 min30 subs6 min90 subs
Bortle 3Rural< 1 min10 subs2 min30 subs6 min90 subs
Bortle 4Rural / suburban transition< 1 min10 subs2 min30 subs6 min93 subs
Bortle 5Suburban< 1 min10 subs2 min30 subs7 min102 subs
Bortle 6Bright suburban< 1 min10 subs2 min32 subs8 min125 subs
Bortle 7Suburban / urban transition< 1 min11 subs3 min43 subs11 min169 subs
Bortle 8City< 1 min15 subs4 min59 subs16 min236 subs
Bortle 9Inner city2 min24 subs6 min95 subs25 min380 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 3 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 NGC 663 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 NGC 663

A rich open cluster in Cassiopeia among several others. Good practice for short-sub star colour.

Caldwell 10 · Open cluster in Cassiopeia · magnitude 7.1 · 16′ · best in Sep, Oct, Nov. Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.

Open clusters are the easiest targets in the sky. The stars are bright, so the aim is colour and tight stars rather than depth: short subs, no filter, and stop before the bright members saturate. The nominal time here gets you clean star colour; more integration only adds background stars.

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 NGC 663 with your eQuinox 2? Did the solid figure match?Anonymous, one tap. It is how the model gets calibrated.

Have an image of the NGC 663 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 NGC 663 · All targets for the eQuinox 2