How long to image the NGC 2903 with the Vaonis Vespera Pro
From a Bortle 6 suburban sky, the Vaonis Vespera Pro needs about 5 h 16 min (1,898 subs of 10 s) for a solid image of the NGC 2903. A quick look takes 1 h 19 min; a showpiece 21 h. Under a Bortle 3 rural sky the solid figure drops to 2 h 12 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 13% 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 | 29 min172 subs | 1 h 54 min686 subs | 7 h 37 min2,741 subs |
| Bortle 2Typical dark site | 30 min181 subs | 2 h723 subs | 8 h 02 min2,890 subs |
| Bortle 3Rural | 33 min199 subs | 2 h 12 min793 subs | 8 h 49 min3,172 subs |
| Bortle 4Rural / suburban transition | 40 min241 subs | 2 h 41 min964 subs | 11 h3,854 subs |
| Bortle 5Suburban | 51 min309 subs | 3 h 26 min1,234 subs | 14 h4,936 subs |
| Bortle 6Bright suburban | 1 h 19 min475 subs | 5 h 16 min1,898 subs | 21 h7,589 subs |
| Bortle 7Suburban / urban transition | 2 h 12 min791 subs | 8 h 47 min3,161 subs | 35 h12,644 subs |
| Bortle 8City | 3 h 33 min1,281 subs | 14 h5,124 subs | 57 h20,493 subs |
| Bortle 9Inner city | 6 h 28 min2,328 subs | 26 h9,309 subs | 100+ h37,233 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 6 h 51 min of run time. The Vespera Pro’s battery is rated at about 11 h, less near freezing, which is cutting it fine; take a power bank. (Bortle 6, solid image; we allow 30% over the integration time, and 30% off the battery for a February 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.
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How it frames
The NGC 2903 is 12.6′ × 6′ across. The Vespera Pro frames 1.62° × 1.62° at 1.65″ per pixel, so it fills 13% 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 12 min793 subs | 3 h 26 min1,234 subs | 8 h 47 min3,161 subs |
| 20 s | 1 h 49 min327 subs | 3 h 02 min548 subs | 8 h 24 min1,511 subs |
| 30 s | 1 h 41 min203 subs | 2 h 55 min350 subs | 8 h 16 min992 subs |
About the NGC 2903
A bright barred spiral below the Sickle of Leo that Messier somehow missed. Bright core, well-defined arms.
UGC 5079 · Galaxy in Leo · magnitude 9.0 · 12.6′ × 6′ · best in Jan, Feb, Mar. 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 2903 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 2903 with the ZWO Seestar S50: 2 h 21 min from Bortle 6
- NGC 2903 with the ZWO Seestar S50 Pro: 2 h 34 min from Bortle 6
- NGC 2903 with the ZWO Seestar S30: 2 h 28 min from Bortle 6
- NGC 2903 with the ZWO Seestar S30 Pro: 2 h 44 min from Bortle 6
- NGC 2903 with the DwarfLab DWARF 3: 3 h 25 min from Bortle 6
- NGC 2903 with the DwarfLab DWARF mini: 2 h 20 min from Bortle 6
- NGC 2903 with the DwarfLab Draco: 1 h 56 min from Bortle 6
- NGC 2903 with the DwarfLab DWARF II: 8 h 04 min from Bortle 6
- NGC 2903 with the Vaonis Vespera II: 2 h 21 min from Bortle 6
- NGC 2903 with the Vaonis Vespera 3: 2 h 15 min from Bortle 6
- NGC 2903 with the Vaonis Vespera Pro 2: 5 h 01 min from Bortle 6
- NGC 2903 with the Unistellar eQuinox 2: 2 h 08 min from Bortle 6
- NGC 2903 with the Unistellar Odyssey: 9 h 55 min from Bortle 6
- NGC 2903 with the Celestron Origin: 37 min from Bortle 6
- NGC 2903 with the Celestron Origin Mark II: 51 min from Bortle 6
All telescopes for the NGC 2903 · All targets for the Vespera Pro