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

From a Bortle 6 suburban sky, the Unistellar eQuinox 2 needs about 3 h 32 min (3,183 subs of 4 s) for a solid image of the Tulip Nebula. A quick look takes 53 min; a showpiece 14 h. Under a Bortle 3 rural sky the solid figure drops to 2 h 01 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.

Tulip Nebula with the Unistellar eQuinox 2: 4 s subs.
SkyQuick lookTarget obvious, still noisySolidClean enough to shareShowpieceSmooth faint detail, print-worthy
Bortle 1Excellent dark site28 min420 subs1 h 52 min1,677 subs7 h 27 min6,706 subs
Bortle 2Typical dark site29 min431 subs1 h 55 min1,723 subs7 h 39 min6,891 subs
Bortle 3Rural30 min453 subs2 h 01 min1,811 subs8 h 03 min7,241 subs
Bortle 4Rural / suburban transition34 min506 subs2 h 15 min2,023 subs8 h 59 min8,089 subs
Bortle 5Suburban39 min590 subs2 h 37 min2,359 subs10 h9,433 subs
Bortle 6Bright suburban53 min796 subs3 h 32 min3,183 subs14 h12,729 subs
Bortle 7Suburban / urban transition1 h 19 min1,189 subs5 h 17 min4,753 subs21 h19,011 subs
Bortle 8City2 h1,798 subs7 h 59 min7,191 subs32 h28,764 subs
Bortle 9Inner city3 h 27 min3,098 subs14 h12,392 subs55 h49,565 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 4 h 36 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 Tulip Nebula is 16′ × 9′ across. The eQuinox 2 frames 0.76° × 0.57° at 1.33″ per pixel, so it fills 47% of the frame’s short side.

Filters

The Tulip 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 Tulip Nebula

A compact hydrogen bloom in Cygnus near the black hole Cygnus X-1. Small and moderately faint; dual-band.

Sh2-101 · Emission nebula in Cygnus · magnitude 9.0 · 16′ × 9′ · best in Jul, Aug, Sep. 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 Tulip 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 Tulip 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 Tulip Nebula · All targets for the eQuinox 2