How long to image the NGC 7331 with the Unistellar eQuinox 2
From a Bortle 6 suburban sky, the Unistellar eQuinox 2 needs about 1 h 55 min (1,726 subs of 4 s) for a solid image of the NGC 7331. A quick look takes 29 min; a showpiece 7 h 40 min. Under a Bortle 3 rural sky the solid figure drops to 1 h 07 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it fills 29% 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 | 15 min233 subs | 1 h 02 min930 subs | 4 h 08 min3,718 subs |
| Bortle 2Typical dark site | 16 min239 subs | 1 h 04 min954 subs | 4 h 14 min3,816 subs |
| Bortle 3Rural | 17 min250 subs | 1 h 07 min1,000 subs | 4 h 27 min4,000 subs |
| Bortle 4Rural / suburban transition | 19 min278 subs | 1 h 14 min1,112 subs | 4 h 57 min4,448 subs |
| Bortle 5Suburban | 21 min323 subs | 1 h 26 min1,290 subs | 5 h 44 min5,159 subs |
| Bortle 6Bright suburban | 29 min432 subs | 1 h 55 min1,726 subs | 7 h 40 min6,901 subs |
| Bortle 7Suburban / urban transition | 43 min639 subs | 2 h 50 min2,555 subs | 11 h10,220 subs |
| Bortle 8City | 1 h 04 min961 subs | 4 h 16 min3,844 subs | 17 h15,374 subs |
| Bortle 9Inner city | 1 h 50 min1,648 subs | 7 h 19 min6,592 subs | 29 h26,366 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 2 h 30 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.)
- 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.
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Everything that fits the eQuinox 2 →
How it frames
The NGC 7331 is 10′ × 4′ across. The eQuinox 2 frames 0.76° × 0.57° at 1.33″ per pixel, so it fills 29% of the frame’s short side.
About the NGC 7331
A tilted spiral often compared to the Milky Way, with a group of background galaxies alongside. Stephan's Quintet is half a degree away.
Caldwell 30 · Galaxy in Pegasus · magnitude 9.5 · 10′ × 4′ · best in Aug, Sep, Oct. 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 7331 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 7331 with the ZWO Seestar S50: 2 h 07 min from Bortle 6
- NGC 7331 with the ZWO Seestar S50 Pro: 2 h 19 min from Bortle 6
- NGC 7331 with the ZWO Seestar S30: 2 h 13 min from Bortle 6
- NGC 7331 with the ZWO Seestar S30 Pro: 2 h 27 min from Bortle 6
- NGC 7331 with the DwarfLab DWARF 3: 3 h 04 min from Bortle 6
- NGC 7331 with the DwarfLab DWARF mini: 2 h 06 min from Bortle 6
- NGC 7331 with the DwarfLab Draco: 1 h 44 min from Bortle 6
- NGC 7331 with the DwarfLab DWARF II: 7 h 14 min from Bortle 6
- NGC 7331 with the Vaonis Vespera II: 2 h 07 min from Bortle 6
- NGC 7331 with the Vaonis Vespera Pro: 4 h 44 min from Bortle 6
- NGC 7331 with the Vaonis Vespera 3: 2 h 01 min from Bortle 6
- NGC 7331 with the Vaonis Vespera Pro 2: 4 h 31 min from Bortle 6
- NGC 7331 with the Unistellar Odyssey: 8 h 52 min from Bortle 6
- NGC 7331 with the Celestron Origin: 34 min from Bortle 6
- NGC 7331 with the Celestron Origin Mark II: 46 min from Bortle 6
All telescopes for the NGC 7331 · All targets for the eQuinox 2