How long to image the Omega Nebula with the Unistellar eQuinox 2

From a Bortle 6 suburban sky, the Unistellar eQuinox 2 needs about 29 min (431 subs of 4 s) for a solid image of the Omega Nebula. A quick look takes 7 min; a showpiece 1 h 55 min. Under a Bortle 3 rural sky the solid figure drops to 17 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it fills 32% of the frame’s short side.

Omega Nebula with the Unistellar eQuinox 2: 4 s subs.
SkyQuick lookTarget obvious, still noisySolidClean enough to shareShowpieceSmooth faint detail, print-worthy
Bortle 1Excellent dark site4 min61 subs16 min243 subs1 h 05 min972 subs
Bortle 2Typical dark site4 min63 subs17 min249 subs1 h 06 min995 subs
Bortle 3Rural4 min65 subs17 min260 subs1 h 09 min1,039 subs
Bortle 4Rural / suburban transition5 min72 subs19 min286 subs1 h 16 min1,144 subs
Bortle 5Suburban5 min82 subs22 min328 subs1 h 27 min1,311 subs
Bortle 6Bright suburban7 min108 subs29 min431 subs1 h 55 min1,721 subs
Bortle 7Suburban / urban transition10 min157 subs42 min626 subs2 h 47 min2,503 subs
Bortle 8City15 min233 subs1 h 02 min929 subs4 h 08 min3,716 subs
Bortle 9Inner city26 min394 subs1 h 45 min1,576 subs7 h6,303 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 37 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 Omega Nebula is 11′ across. The eQuinox 2 frames 0.76° × 0.57° at 1.33″ per pixel, so it fills 32% of the frame’s short side.

Filters

The Omega Nebula is an emission target, where a dual-band filter would normally cut the time several-fold from a lit sky, but the eQuinox 2 has no dual-band option: 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 figures above are for the No filter position, and a darker sky is the lever that remains.

About the Omega Nebula

A bright, compact swan-shaped emission nebula, one of the brightest in the sky per unit area. Excellent from suburban skies.

M17, NGC 6618, Swan Nebula · Emission nebula in Sagittarius · magnitude 6.0 · 11′ · best in Jun, Jul, Aug. Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.

Emission nebulae glow in a few narrow lines, mostly hydrogen-alpha (deep red) and doubly ionised oxygen (teal). A dual-band filter passes those lines and blocks most skyglow, which is why it cuts the time needed from a suburban sky so dramatically. Use it. From a genuinely dark site the gain is smaller because there is less skyglow to block, and read noise becomes the limit, which is where longer subs (EQ mode, or Expert Mode on a Vespera) earn their keep.

Stars lose colour through a dual-band filter; a short broadband stack blended in fixes that if you care.

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

Have an image of the Omega Nebula 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 Omega Nebula · All targets for the eQuinox 2