How long to image the NGC 891 with the Vaonis Vespera Pro
From a Bortle 6 suburban sky, the Vaonis Vespera Pro needs about 6 h 08 min (2,210 subs of 10 s) for a solid image of the NGC 891. A quick look takes 1 h 32 min; a showpiece 25 h. Under a Bortle 3 rural sky the solid figure drops to 2 h 32 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 fills 14% 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 | 33 min197 subs | 2 h 11 min787 subs | 8 h 45 min3,148 subs |
| Bortle 2Typical dark site | 35 min208 subs | 2 h 18 min831 subs | 9 h 14 min3,323 subs |
| Bortle 3Rural | 38 min229 subs | 2 h 32 min914 subs | 10 h3,653 subs |
| Bortle 4Rural / suburban transition | 46 min279 subs | 3 h 06 min1,114 subs | 12 h4,454 subs |
| Bortle 5Suburban | 1 h358 subs | 3 h 58 min1,431 subs | 16 h5,723 subs |
| Bortle 6Bright suburban | 1 h 32 min553 subs | 6 h 08 min2,210 subs | 25 h8,837 subs |
| Bortle 7Suburban / urban transition | 2 h 34 min924 subs | 10 h3,693 subs | 41 h14,770 subs |
| Bortle 8City | 4 h 10 min1,499 subs | 17 h5,996 subs | 67 h23,982 subs |
| Bortle 9Inner city | 7 h 34 min2,727 subs | 30 h10,908 subs | 120+ h43,629 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 7 h 59 min of run time. That is more than one night: over 2 nights, about 3 h 59 min each. The Vespera Pro’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, and 30% off the battery for a November night.)
- USB-C PD power bank 20000mAh 30WExtends the 11 h battery; 30 W PD per Vaonis.
- 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.
Affiliate links: the retailer pays us a small commission and you pay the same price. These are search links to the named product, not endorsements of a particular listing; check the listing matches your model.
Everything that fits the Vespera Pro →
How it frames
The NGC 891 is 13.5′ × 2.5′ across. The Vespera Pro frames 1.62° × 1.62° at 1.65″ per pixel, so it fills 14% of the frame’s short side.
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 | 2 h 32 min914 subs | 3 h 58 min1,431 subs | 10 h3,693 subs |
| 20 s | 2 h 05 min376 subs | 3 h 31 min634 subs | 9 h 48 min1,765 subs |
| 30 s | 1 h 56 min232 subs | 3 h 22 min405 subs | 9 h 39 min1,159 subs |
About the NGC 891
A perfect edge-on spiral split by a dust lane. Faint per pixel; a dark sky or a long stack shows the lane.
Caldwell 23, Silver Sliver · Galaxy in Andromeda · magnitude 10.0 · 13.5′ × 2.5′ · best in Oct, Nov, Dec. 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 Vaonis Vespera Pro
The square-sensor Vespera with 2 µm pixels. Higher resolution than the II, and correspondingly slower per pixel: expect around double the time for the same per-pixel SNR. Run-out in 2026 and replaced by the Vespera Pro 2.
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.
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 NGC 891 from a Vespera Pro? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- NGC 891 with the ZWO Seestar S50: 2 h 44 min from Bortle 6
- NGC 891 with the ZWO Seestar S50 Pro: 3 h from Bortle 6
- NGC 891 with the ZWO Seestar S30: 2 h 53 min from Bortle 6
- NGC 891 with the ZWO Seestar S30 Pro: 3 h 10 min from Bortle 6
- NGC 891 with the DwarfLab DWARF 3: 3 h 58 min from Bortle 6
- NGC 891 with the DwarfLab DWARF mini: 2 h 43 min from Bortle 6
- NGC 891 with the DwarfLab Draco: 2 h 15 min from Bortle 6
- NGC 891 with the DwarfLab DWARF II: 9 h 24 min from Bortle 6
- NGC 891 with the Vaonis Vespera II: 2 h 44 min from Bortle 6
- NGC 891 with the Vaonis Vespera 3: 2 h 37 min from Bortle 6
- NGC 891 with the Vaonis Vespera Pro 2: 5 h 51 min from Bortle 6
- NGC 891 with the Unistellar eQuinox 2: 2 h 30 min from Bortle 6
- NGC 891 with the Unistellar Odyssey: 12 h from Bortle 6
- NGC 891 with the Celestron Origin: 43 min from Bortle 6
- NGC 891 with the Celestron Origin Mark II: 59 min from Bortle 6
All telescopes for the NGC 891 · All targets for the Vespera Pro