How long to image the M90 with the Vaonis Vespera Pro
From a Bortle 6 suburban sky, the Vaonis Vespera Pro needs about 5 h 40 min (2,038 subs of 10 s) for a solid image of the M90. A quick look takes 1 h 25 min; a showpiece 23 h. Under a Bortle 3 rural sky the solid figure drops to 2 h 24 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 10% 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 | 31 min187 subs | 2 h 04 min747 subs | 8 h 18 min2,988 subs |
| Bortle 2Typical dark site | 33 min197 subs | 2 h 11 min787 subs | 8 h 44 min3,146 subs |
| Bortle 3Rural | 36 min216 subs | 2 h 24 min862 subs | 9 h 34 min3,446 subs |
| Bortle 4Rural / suburban transition | 43 min261 subs | 2 h 54 min1,044 subs | 12 h4,173 subs |
| Bortle 5Suburban | 55 min333 subs | 3 h 42 min1,332 subs | 15 h5,325 subs |
| Bortle 6Bright suburban | 1 h 25 min510 subs | 5 h 40 min2,038 subs | 23 h8,152 subs |
| Bortle 7Suburban / urban transition | 2 h 21 min847 subs | 9 h 24 min3,385 subs | 38 h13,537 subs |
| Bortle 8City | 3 h 48 min1,369 subs | 15 h5,475 subs | 61 h21,899 subs |
| Bortle 9Inner city | 6 h 54 min2,484 subs | 28 h9,933 subs | 110+ h39,732 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 7 h 22 min of run time. That is more than one night: over 2 nights, about 3 h 41 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.)
- 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.
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How it frames
The M90 is 9.5′ × 4.5′ across. The Vespera Pro frames 1.62° × 1.62° at 1.65″ per pixel, so it fills 10% 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 24 min862 subs | 3 h 42 min1,332 subs | 9 h 24 min3,385 subs |
| 20 s | 1 h 59 min357 subs | 3 h 17 min592 subs | 8 h 59 min1,619 subs |
| 30 s | 1 h 51 min222 subs | 3 h 09 min378 subs | 8 h 51 min1,063 subs |
About the M90
A large spiral whose arms have been stripped by the cluster medium. Smooth and elongated.
NGC 4569 · Galaxy in Virgo · magnitude 9.5 · 9.5′ × 4.5′ · best in Mar, Apr, May. 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 M90 from a Vespera Pro? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- M90 with the ZWO Seestar S50: 2 h 32 min from Bortle 6
- M90 with the ZWO Seestar S50 Pro: 2 h 46 min from Bortle 6
- M90 with the ZWO Seestar S30: 2 h 39 min from Bortle 6
- M90 with the ZWO Seestar S30 Pro: 2 h 56 min from Bortle 6
- M90 with the DwarfLab DWARF 3: 3 h 40 min from Bortle 6
- M90 with the DwarfLab DWARF mini: 2 h 31 min from Bortle 6
- M90 with the DwarfLab Draco: 2 h 04 min from Bortle 6
- M90 with the DwarfLab DWARF II: 8 h 39 min from Bortle 6
- M90 with the Vaonis Vespera II: 2 h 32 min from Bortle 6
- M90 with the Vaonis Vespera 3: 2 h 25 min from Bortle 6
- M90 with the Vaonis Vespera Pro 2: 5 h 24 min from Bortle 6
- M90 with the Unistellar eQuinox 2: 2 h 18 min from Bortle 6
- M90 with the Unistellar Odyssey: 11 h from Bortle 6
- M90 with the Celestron Origin: 40 min from Bortle 6
- M90 with the Celestron Origin Mark II: 55 min from Bortle 6
All telescopes for the M90 · All targets for the Vespera Pro