How long to image the Rosette Nebula with the Vaonis Vespera II
From a Bortle 6 suburban sky, the Vaonis Vespera II needs about 2 h 15 min (813 subs of 10 s) for a solid image of the Rosette Nebula. A quick look takes 34 min; a showpiece 9 h 02 min. Under a Bortle 3 rural sky the solid figure drops to 51 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 only just fits, at 93% of the short side.
| Sky | Quick lookTarget obvious, still noisy | SolidClean enough to share | ShowpieceSmooth faint detail, print-worthy |
|---|---|---|---|
| Bortle 1Excellent dark site | 11 min65 subs | 43 min257 subs | 2 h 51 min1,027 subs |
| Bortle 2Typical dark site | 11 min69 subs | 46 min274 subs | 3 h 02 min1,095 subs |
| Bortle 3Rural | 13 min77 subs | 51 min306 subs | 3 h 24 min1,224 subs |
| Bortle 4Rural / suburban transition | 16 min97 subs | 1 h 04 min385 subs | 4 h 16 min1,538 subs |
| Bortle 5Suburban | 21 min128 subs | 1 h 25 min509 subs | 5 h 39 min2,034 subs |
| Bortle 6Bright suburban | 34 min204 subs | 2 h 15 min813 subs | 9 h 02 min3,251 subs |
| Bortle 7Suburban / urban transition | 58 min349 subs | 3 h 52 min1,393 subs | 15 h5,571 subs |
| Bortle 8City | 1 h 36 min574 subs | 6 h 22 min2,294 subs | 25 h9,173 subs |
| Bortle 9Inner city | 2 h 56 min1,054 subs | 12 h4,214 subs | 47 h16,855 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 2 h 56 min of run time. The Vespera II’s battery is rated at about 4 h, less near freezing, so the session needs an external power bank. (Bortle 6, solid image; we allow 30% over the integration time, and 30% off the battery for a January night.)
- 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.
- 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.
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Everything that fits the Vespera II →
How it frames
The Rosette Nebula is 80′ × 60′ across. The Vespera II frames 2.55° × 1.44° at 2.39″ per pixel, so it only just fits, at 93% of the short side. Centre it carefully: there is no room to crop back afterwards.
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 | 51 min306 subs | 1 h 25 min509 subs | 3 h 52 min1,393 subs |
| 20 s | 43 min130 subs | 1 h 17 min231 subs | 3 h 44 min673 subs |
| 30 s | 40 min81 subs | 1 h 14 min149 subs | 3 h 42 min444 subs |
With and without the dual-band filter
| Filter | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| No filter | 51 min306 subs | 1 h 25 min509 subs | 3 h 52 min1,393 subs |
| dual-band (Dual Band filter), clip-on | 59 min357 subs | 1 h 10 min419 subs | 1 h 55 min690 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 Rosette Nebula
A ring of hydrogen more than a degree across around the cluster NGC 2244. One of the best dual-band targets of winter and forgiving of light pollution.
NGC 2237, NGC 2244, Caldwell 49 · Emission nebula in Monoceros · magnitude 9.0 · 80′ × 60′ · best in Dec, Jan, Feb. Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.
Emission nebulae glow in a few narrow lines, mostly hydrogen-alpha (deep red) and doubly ionised oxygen (teal). A dual-band filter passes those lines and blocks most skyglow, which is why it cuts the time needed from a suburban sky so dramatically. Use it. From a genuinely dark site the gain is smaller because there is less skyglow to block, and read noise becomes the limit, which is where longer subs (EQ mode, or Expert Mode on a Vespera) earn their keep.
Stars lose colour through a dual-band filter; a short broadband stack blended in fixes that if you care.
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 Rosette 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
- Rosette Nebula with the ZWO Seestar S50: 1 h 25 min from Bortle 6
- Rosette Nebula with the ZWO Seestar S50 Pro: 1 h 36 min from Bortle 6
- Rosette Nebula with the ZWO Seestar S30: 1 h 39 min from Bortle 6
- Rosette Nebula with the ZWO Seestar S30 Pro: 1 h 43 min from Bortle 6
- Rosette Nebula with the DwarfLab DWARF 3: 1 h 46 min from Bortle 6
- Rosette Nebula with the DwarfLab DWARF mini: 1 h 24 min from Bortle 6
- Rosette Nebula with the DwarfLab Draco: 1 h 08 min from Bortle 6
- Rosette Nebula with the DwarfLab DWARF II: 7 h 45 min from Bortle 6
- Rosette Nebula with the Vaonis Vespera Pro: 5 h 04 min from Bortle 6
- Rosette Nebula with the Vaonis Vespera 3: 2 h 09 min from Bortle 6
- Rosette Nebula with the Vaonis Vespera Pro 2: 4 h 49 min from Bortle 6
- Rosette Nebula with the Unistellar eQuinox 2: 2 h 04 min from Bortle 6
- Rosette Nebula with the Unistellar Odyssey: 9 h 33 min from Bortle 6
- Rosette Nebula with the Celestron Origin: 36 min from Bortle 6
- Rosette Nebula with the Celestron Origin Mark II: 49 min from Bortle 6
All telescopes for the Rosette Nebula · All targets for the Vespera II