How long to image the Abell 39 with the Unistellar eQuinox 2
From a Bortle 6 suburban sky, the Unistellar eQuinox 2 needs about 34 h (30,640 subs of 4 s) for a solid image of the Abell 39. A quick look takes 8 h 31 min; a showpiece 140+ h. Under a Bortle 3 rural sky the solid figure drops to 19 h. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it fills 8% 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 | 4 h 24 min3,963 subs | 18 h15,851 subs | 70 h63,404 subs |
| Bortle 2Typical dark site | 4 h 32 min4,077 subs | 18 h16,306 subs | 72 h65,221 subs |
| Bortle 3Rural | 4 h 46 min4,292 subs | 19 h17,165 subs | 76 h68,658 subs |
| Bortle 4Rural / suburban transition | 5 h 21 min4,812 subs | 21 h19,247 subs | 86 h76,985 subs |
| Bortle 5Suburban | 6 h 16 min5,637 subs | 25 h22,546 subs | 100+ h90,182 subs |
| Bortle 6Bright suburban | 8 h 31 min7,660 subs | 34 h30,640 subs | 140+ h122,560 subs |
| Bortle 7Suburban / urban transition | 13 h11,517 subs | 51 h46,065 subs | 200+ h184,257 subs |
| Bortle 8City | 19 h17,504 subs | 78 h70,013 subs | 310+ h280,050 subs |
| Bortle 9Inner city | 34 h30,272 subs | 130+ h121,087 subs | 540+ h484,348 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 44 h of run time. That is more than one night: over 7 nights, about 6 h 19 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.)
- 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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How it frames
The Abell 39 is 2.9′ across. The eQuinox 2 frames 0.76° × 0.57° at 1.33″ per pixel, so it fills 8% of the frame’s short side.
Filters
The Abell 39 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 Abell 39
A near-perfect faint sphere in Hercules. Very low surface brightness, an OIII target for dark skies and long dual-band stacks.
PN A66 39 · Planetary nebula in Hercules · magnitude 13.7 · 2.9′ · best in May, Jun, Jul. Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.
Planetary nebulae are small but intensely bright per pixel in OIII and H-alpha, so they respond very well to a dual-band filter and do not need much time for the main shell. The faint outer halos most of them have are a different proposition and need hours. Keep subs short if the central region saturates.
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 Abell 39 from a eQuinox 2? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- Abell 39 with the ZWO Seestar S50: 22 h from Bortle 6
- Abell 39 with the ZWO Seestar S50 Pro: 24 h from Bortle 6
- Abell 39 with the ZWO Seestar S30: 26 h from Bortle 6
- Abell 39 with the ZWO Seestar S30 Pro: 26 h from Bortle 6
- Abell 39 with the DwarfLab DWARF 3: 26 h from Bortle 6
- Abell 39 with the DwarfLab DWARF mini: 21 h from Bortle 6
- Abell 39 with the DwarfLab Draco: 17 h from Bortle 6
- Abell 39 with the DwarfLab DWARF II: 130+ h from Bortle 6
- Abell 39 with the Vaonis Vespera II: 37 h from Bortle 6
- Abell 39 with the Vaonis Vespera Pro: 83 h from Bortle 6
- Abell 39 with the Vaonis Vespera 3: 35 h from Bortle 6
- Abell 39 with the Vaonis Vespera Pro 2: 79 h from Bortle 6
- Abell 39 with the Unistellar Odyssey: 160+ h from Bortle 6
- Abell 39 with the Celestron Origin: 9 h 41 min from Bortle 6
- Abell 39 with the Celestron Origin Mark II: 13 h from Bortle 6
All telescopes for the Abell 39 · All targets for the eQuinox 2