How long to image the Witch Head Nebula with the Unistellar eQuinox 2
From a Bortle 6 suburban sky, the Unistellar eQuinox 2 needs about 38 h (33,974 subs of 4 s) for a solid image of the Witch Head Nebula. A quick look takes 9 h 26 min; a showpiece 150+ h. Under a Bortle 3 rural sky the solid figure drops to 21 h. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it is 5.3× wider than the frame.
| Sky | Quick lookTarget obvious, still noisy | SolidClean enough to share | ShowpieceSmooth faint detail, print-worthy |
|---|---|---|---|
| Bortle 1Excellent dark site | 4 h 51 min4,366 subs | 19 h17,464 subs | 78 h69,855 subs |
| Bortle 2Typical dark site | 5 h4,493 subs | 20 h17,971 subs | 80 h71,883 subs |
| Bortle 3Rural | 5 h 15 min4,733 subs | 21 h18,930 subs | 84 h75,720 subs |
| Bortle 4Rural / suburban transition | 5 h 54 min5,314 subs | 24 h21,254 subs | 94 h85,016 subs |
| Bortle 5Suburban | 6 h 56 min6,235 subs | 28 h24,937 subs | 110+ h99,748 subs |
| Bortle 6Bright suburban | 9 h 26 min8,494 subs | 38 h33,974 subs | 150+ h135,896 subs |
| Bortle 7Suburban / urban transition | 14 h12,799 subs | 57 h51,194 subs | 230+ h204,774 subs |
| Bortle 8City | 22 h19,483 subs | 87 h77,930 subs | 350+ h311,717 subs |
| Bortle 9Inner city | 37 h33,738 subs | 150+ h134,949 subs | 600+ h539,793 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 49 h of run time. That is more than one night: over 8 nights, about 6 h 08 min each. The eQuinox 2’s battery (rated about 11 h) should cover each night; 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 December night.)
- USB-C power bank 20000mAh 5V 2AUnistellar asks for a 5 V 2 A output; PD is not needed.
- red LED head torchRed light keeps your night vision; white light costs you twenty minutes of dark adaptation every time.
- hand warmers long lastingAir-activated packs give hours of heat for the person; winter nights are long and you spend most of them standing still.
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Everything that fits the eQuinox 2 →
How it frames
The Witch Head Nebula is 180′ × 60′ across. The eQuinox 2 frames 0.76° × 0.57° at 1.33″ per pixel, so it is 5.3× wider than the frame. A mosaic, or choosing the part you want and letting the rest go, is how it gets shot on this scope.
About the Witch Head Nebula
A very faint blue reflection nebula lit by Rigel. A dark-sky, all-night, broadband project; it is one of the hardest objects on this list.
IC 2118 · Reflection nebula in Eridanus · magnitude 13.0 · 180′ × 60′ · best in Nov, Dec, Jan. Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.
Reflection nebulae are starlight scattered by dust, so they are broadband and blue. A dual-band filter removes almost all of it; do not use one. These are among the faintest structures a smart scope can attempt and the figures run long. A dark sky matters more here than for any other type, and the Moon must be down.
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.
Have an image of the Witch Head 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
- Witch Head Nebula with the ZWO Seestar S50: 41 h from Bortle 6
- Witch Head Nebula with the ZWO Seestar S50 Pro: 44 h from Bortle 6
- Witch Head Nebula with the ZWO Seestar S30: 43 h from Bortle 6
- Witch Head Nebula with the ZWO Seestar S30 Pro: 47 h from Bortle 6
- Witch Head Nebula with the DwarfLab DWARF 3: 59 h from Bortle 6
- Witch Head Nebula with the DwarfLab DWARF mini: 40 h from Bortle 6
- Witch Head Nebula with the DwarfLab Draco: 33 h from Bortle 6
- Witch Head Nebula with the DwarfLab DWARF II: 140+ h from Bortle 6
- Witch Head Nebula with the Vaonis Vespera II: 41 h from Bortle 6
- Witch Head Nebula with the Vaonis Vespera Pro: 91 h from Bortle 6
- Witch Head Nebula with the Vaonis Vespera 3: 39 h from Bortle 6
- Witch Head Nebula with the Vaonis Vespera Pro 2: 87 h from Bortle 6
- Witch Head Nebula with the Unistellar Odyssey: 180+ h from Bortle 6
- Witch Head Nebula with the Celestron Origin: 11 h from Bortle 6
- Witch Head Nebula with the Celestron Origin Mark II: 15 h from Bortle 6
All telescopes for the Witch Head Nebula · All targets for the eQuinox 2