How long to image the Cat's Eye Nebula with the Vaonis Vespera II
From a Bortle 6 suburban sky, the Vaonis Vespera II needs about 12 min (75 subs of 10 s) for a solid image of the Cat's Eye Nebula. A quick look takes 3 min; a showpiece 49 min. Under a Bortle 3 rural sky the solid figure drops to 7 min. At Bortle 6 the limit is skyglow, so a darker site or a filter helps more than longer subs. In this scope's field it is small in the frame, about 10 pixels across.
| Sky | Quick lookTarget obvious, still noisy | SolidClean enough to share | ShowpieceSmooth faint detail, print-worthy |
|---|---|---|---|
| Bortle 1Excellent dark site | 2 min10 subs | 6 min37 subs | 24 min146 subs |
| Bortle 2Typical dark site | 2 min10 subs | 6 min38 subs | 25 min150 subs |
| Bortle 3Rural | 2 min10 subs | 7 min40 subs | 26 min159 subs |
| Bortle 4Rural / suburban transition | 2 min12 subs | 7 min45 subs | 30 min180 subs |
| Bortle 5Suburban | 2 min14 subs | 9 min54 subs | 36 min214 subs |
| Bortle 6Bright suburban | 3 min19 subs | 12 min75 subs | 49 min297 subs |
| Bortle 7Suburban / urban transition | 5 min29 subs | 19 min114 subs | 1 h 16 min455 subs |
| Bortle 8City | 7 min44 subs | 29 min175 subs | 1 h 56 min699 subs |
| Bortle 9Inner city | 13 min77 subs | 51 min306 subs | 3 h 23 min1,221 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 16 min of run time. The Vespera II’s battery (rated about 4 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 PD power bank 20000mAh 30WOnly four hours inside; Vaonis specifies a 30 W PD source. C-to-C cable not included.
- Vaonis Vespera hygrometer sensorTriggers the built-in demister automatically; the correct dew accessory for the II.
- 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 Vespera II →
How it frames
The Cat's Eye Nebula is 0.4′ × 0.3′ across. The Vespera II frames 2.55° × 1.44° at 2.39″ per pixel, so it is small in the frame, about 10 pixels across. It is worth doing, but the result is a crop rather than a full frame; a longer focal length would resolve more of it.
Longer subs
10 s subs by default; Expert Mode manual targets allow 1 to 30 s. Alt-azimuth only, no EQ mode. Time for a solid image by sub length:
| Sub length | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| 10 s | 7 min40 subs | 9 min54 subs | 19 min114 subs |
| 20 s | 10 min30 subs | 10 min30 subs | 18 min56 subs |
| 30 s | 15 min30 subs | 15 min30 subs | 18 min37 subs |
With and without the dual-band filter
| Filter | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| No filter | 7 min40 subs | 9 min54 subs | 19 min114 subs |
| dual-band (Dual Band filter), clip-on | 9 min52 subs | 9 min56 subs | 12 min74 subs |
The Vespera II has no built-in dual-band filter. Optional clip-on Vaonis filters: dual-band, light-pollution (CLS) and solar; the app detects which is fitted. On an emission target like this it is the single biggest upgrade you can make.
About the Cat's Eye Nebula
A tiny, intensely bright planetary. The core saturates in seconds; the faint outer halo around it is a long dual-band project.
NGC 6543, Caldwell 6 · Planetary nebula in Draco · magnitude 9.0 · 0.4′ × 0.3′ · 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 Vaonis Vespera II
A 50 mm quadruplet on an 8 MP sensor with Vaonis’s mosaic mode for wide fields. Same optics class as the Seestar S50, four times the pixels.
10 s subs by default; Expert Mode manual targets allow 1 to 30 s. Alt-azimuth only, no EQ mode. Optional clip-on Vaonis filters: dual-band, light-pollution (CLS) and solar; the app detects which is fitted.
Longer subs matter most under dark skies, where read noise rather than skyglow sets the floor. From a city the difference between 10 s and 30 s subs is small; from a rural site it can halve the total time, especially with a dual-band filter in place.
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 Cat's Eye Nebula from a Vespera II? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- Cat's Eye Nebula with the ZWO Seestar S50: 10 min from Bortle 6
- Cat's Eye Nebula with the ZWO Seestar S50 Pro: 11 min from Bortle 6
- Cat's Eye Nebula with the ZWO Seestar S30: 11 min from Bortle 6
- Cat's Eye Nebula with the ZWO Seestar S30 Pro: 12 min from Bortle 6
- Cat's Eye Nebula with the DwarfLab DWARF 3: 14 min from Bortle 6
- Cat's Eye Nebula with the DwarfLab DWARF mini: 10 min from Bortle 6
- Cat's Eye Nebula with the DwarfLab Draco: 15 min from Bortle 6
- Cat's Eye Nebula with the DwarfLab DWARF II: 40 min from Bortle 6
- Cat's Eye Nebula with the Vaonis Vespera Pro: 27 min from Bortle 6
- Cat's Eye Nebula with the Vaonis Vespera 3: 12 min from Bortle 6
- Cat's Eye Nebula with the Vaonis Vespera Pro 2: 26 min from Bortle 6
- Cat's Eye Nebula with the Unistellar eQuinox 2: 10 min from Bortle 6
- Cat's Eye Nebula with the Unistellar Odyssey: 46 min from Bortle 6
- Cat's Eye Nebula with the Celestron Origin: 5 min from Bortle 6
- Cat's Eye Nebula with the Celestron Origin Mark II: 5 min from Bortle 6
All telescopes for the Cat's Eye Nebula · All targets for the Vespera II