How long to image the NGC 891 with the Unistellar eQuinox 2
From a Bortle 6 suburban sky, the Unistellar eQuinox 2 needs about 2 h 30 min (2,250 subs of 4 s) for a solid image of the NGC 891. A quick look takes 37 min; a showpiece 10 h. Under a Bortle 3 rural sky the solid figure drops to 1 h 26 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it fills 39% of the frame’s short side.
| Sky | Quick lookTarget obvious, still noisy | SolidClean enough to share | ShowpieceSmooth faint detail, print-worthy |
|---|---|---|---|
| Bortle 1Excellent dark site | 20 min299 subs | 1 h 20 min1,196 subs | 5 h 19 min4,782 subs |
| Bortle 2Typical dark site | 20 min307 subs | 1 h 22 min1,228 subs | 5 h 27 min4,911 subs |
| Bortle 3Rural | 21 min323 subs | 1 h 26 min1,289 subs | 5 h 44 min5,156 subs |
| Bortle 4Rural / suburban transition | 24 min360 subs | 1 h 36 min1,438 subs | 6 h 23 min5,750 subs |
| Bortle 5Suburban | 28 min419 subs | 1 h 51 min1,673 subs | 7 h 26 min6,690 subs |
| Bortle 6Bright suburban | 37 min563 subs | 2 h 30 min2,250 subs | 10 h8,998 subs |
| Bortle 7Suburban / urban transition | 56 min838 subs | 3 h 43 min3,349 subs | 15 h13,395 subs |
| Bortle 8City | 1 h 24 min1,264 subs | 5 h 37 min5,056 subs | 22 h20,222 subs |
| Bortle 9Inner city | 2 h 25 min2,174 subs | 9 h 40 min8,696 subs | 39 h34,782 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 3 h 15 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, and 30% off the battery for a November 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.
Affiliate links: the retailer pays us a small commission and you pay the same price. These are search links to the named product, not endorsements of a particular listing; check the listing matches your model.
Everything that fits the eQuinox 2 →
How it frames
The NGC 891 is 13.5′ × 2.5′ across. The eQuinox 2 frames 0.76° × 0.57° at 1.33″ per pixel, so it fills 39% of the frame’s short side.
About the NGC 891
A perfect edge-on spiral split by a dust lane. Faint per pixel; a dark sky or a long stack shows the lane.
Caldwell 23, Silver Sliver · Galaxy in Andromeda · magnitude 10.0 · 13.5′ × 2.5′ · best in Oct, Nov, Dec. Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.
Galaxies are broadband targets: their light is mostly starlight spread across the spectrum, so a dual-band filter throws most of it away and makes things slower, not faster. Shoot without a filter (or with a plain UV/IR cut) and rely on total time and a dark sky. The core of a galaxy is usually many times brighter than its outer disc, so a short stack shows the nucleus long before the arms; the figures here are for the arms and disc, not the core.
Field rotation in Alt-Az mode crops the edges of the stack over a long session, so on a big galaxy re-centre now and then or use EQ mode where your scope supports it.
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 NGC 891 from a eQuinox 2? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- NGC 891 with the ZWO Seestar S50: 2 h 44 min from Bortle 6
- NGC 891 with the ZWO Seestar S50 Pro: 3 h from Bortle 6
- NGC 891 with the ZWO Seestar S30: 2 h 53 min from Bortle 6
- NGC 891 with the ZWO Seestar S30 Pro: 3 h 10 min from Bortle 6
- NGC 891 with the DwarfLab DWARF 3: 3 h 58 min from Bortle 6
- NGC 891 with the DwarfLab DWARF mini: 2 h 43 min from Bortle 6
- NGC 891 with the DwarfLab Draco: 2 h 15 min from Bortle 6
- NGC 891 with the DwarfLab DWARF II: 9 h 24 min from Bortle 6
- NGC 891 with the Vaonis Vespera II: 2 h 44 min from Bortle 6
- NGC 891 with the Vaonis Vespera Pro: 6 h 08 min from Bortle 6
- NGC 891 with the Vaonis Vespera 3: 2 h 37 min from Bortle 6
- NGC 891 with the Vaonis Vespera Pro 2: 5 h 51 min from Bortle 6
- NGC 891 with the Unistellar Odyssey: 12 h from Bortle 6
- NGC 891 with the Celestron Origin: 43 min from Bortle 6
- NGC 891 with the Celestron Origin Mark II: 59 min from Bortle 6
All telescopes for the NGC 891 · All targets for the eQuinox 2