How long to image the M28 with the Unistellar eQuinox 2
From a Bortle 6 suburban sky, the Unistellar eQuinox 2 needs about 5 min (79 subs of 4 s) for a solid image of the M28. A quick look takes 1 min; a showpiece 21 min. Under a Bortle 3 rural sky the solid figure drops to 3 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.
| Sky | Quick lookTarget obvious, still noisy | SolidClean enough to share | ShowpieceSmooth faint detail, print-worthy |
|---|---|---|---|
| Bortle 1Excellent dark site | < 1 min13 subs | 3 min50 subs | 13 min198 subs |
| Bortle 2Typical dark site | < 1 min13 subs | 3 min51 subs | 13 min201 subs |
| Bortle 3Rural | < 1 min13 subs | 3 min52 subs | 14 min208 subs |
| Bortle 4Rural / suburban transition | < 1 min14 subs | 4 min56 subs | 15 min224 subs |
| Bortle 5Suburban | 1 min16 subs | 4 min63 subs | 17 min250 subs |
| Bortle 6Bright suburban | 1 min20 subs | 5 min79 subs | 21 min313 subs |
| Bortle 7Suburban / urban transition | 2 min28 subs | 7 min109 subs | 29 min434 subs |
| Bortle 8City | 3 min39 subs | 10 min156 subs | 41 min621 subs |
| Bortle 9Inner city | 4 min64 subs | 17 min255 subs | 1 h 08 min1,020 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 7 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 M28 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.
About the M28
A compact globular near Lambda Sagittarii, a degree from M22. Small and quick.
NGC 6626 · Globular cluster in Sagittarius · magnitude 6.8 · 11′ · best in Jun, Jul, Aug. Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.
Globular clusters are point sources packed tight, so they come quickly: the core resolves into stars within a handful of minutes on any smart scope. More time deepens the halo and pulls in the faint outer members. Use short subs so the core does not saturate into a white blob, and no filter.
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 M28 from a eQuinox 2? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- M28 with the ZWO Seestar S50: 6 min from Bortle 6
- M28 with the ZWO Seestar S50 Pro: 7 min from Bortle 6
- M28 with the ZWO Seestar S30: 7 min from Bortle 6
- M28 with the ZWO Seestar S30 Pro: 7 min from Bortle 6
- M28 with the DwarfLab DWARF 3: 9 min from Bortle 6
- M28 with the DwarfLab DWARF mini: 8 min from Bortle 6
- M28 with the DwarfLab Draco: 15 min from Bortle 6
- M28 with the DwarfLab DWARF II: 20 min from Bortle 6
- M28 with the Vaonis Vespera II: 6 min from Bortle 6
- M28 with the Vaonis Vespera Pro: 14 min from Bortle 6
- M28 with the Vaonis Vespera 3: 6 min from Bortle 6
- M28 with the Vaonis Vespera Pro 2: 13 min from Bortle 6
- M28 with the Unistellar Odyssey: 23 min from Bortle 6
- M28 with the Celestron Origin: 5 min from Bortle 6
- M28 with the Celestron Origin Mark II: 5 min from Bortle 6