How long to image the Spindle Galaxy with the ZWO Seestar S30 Pro
From a Bortle 6 suburban sky, the ZWO Seestar S30 Pro needs about 27 min (164 subs of 10 s) for a solid image of the Spindle Galaxy. A quick look takes 7 min; a showpiece 1 h 49 min. Under a Bortle 3 rural sky the solid figure drops to 13 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 3% 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 | 3 min19 subs | 12 min73 subs | 48 min291 subs |
| Bortle 2Typical dark site | 3 min19 subs | 13 min76 subs | 50 min302 subs |
| Bortle 3Rural | 3 min21 subs | 13 min81 subs | 54 min323 subs |
| Bortle 4Rural / suburban transition | 4 min24 subs | 16 min94 subs | 1 h 02 min374 subs |
| Bortle 5Suburban | 5 min29 subs | 19 min114 subs | 1 h 16 min455 subs |
| Bortle 6Bright suburban | 7 min41 subs | 27 min164 subs | 1 h 49 min654 subs |
| Bortle 7Suburban / urban transition | 11 min65 subs | 43 min259 subs | 2 h 52 min1,033 subs |
| Bortle 8City | 17 min102 subs | 1 h 08 min406 subs | 4 h 30 min1,621 subs |
| Bortle 9Inner city | 30 min180 subs | 2 h719 subs | 7 h 59 min2,874 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 35 min of run time. The Seestar S30 Pro’s battery (rated about 5 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 power bank 10000mAh 5V 3A5 V 3 A input and it runs while charging.
- Seestar S30 Pro dew shieldActive anti-dew is built in; a shield adds margin. The S30 Pro front differs from the S30, so check the listing.
- 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 Seestar S30 Pro →
How it frames
The Spindle Galaxy is 4.7′ × 1.9′ across. The Seestar S30 Pro frames 3.99° × 2.24° at 3.74″ per pixel, so it fills 3% of the frame’s short side.
Longer subs
10, 20 and 30 s in Alt-Az; 60 s only in EQ mode, which needs the TH10 head. Time for a solid image by sub length:
| Sub length | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| 10 s | 13 min81 subs | 19 min114 subs | 43 min259 subs |
| 20 s | 12 min36 subs | 17 min53 subs | 42 min125 subs |
| 30 s | 15 min30 subs | 17 min35 subs | 41 min83 subs |
| 60 s | 30 min30 subs | 30 min30 subs | 41 min41 subs |
Leave the dual-band filter out for the Spindle Galaxy. It is a galaxy, and it shines right across the spectrum. A dual-band filter keeps two emission lines and throws the rest away, so most of the light you came for is being stopped along with the sky. From a Bortle 6 sky it would be roughly 12 times slower.
About the Spindle Galaxy
An edge-on lenticular with a thin dust lane. Small, but its surface brightness is decent.
M102, NGC 5866 · Galaxy in Draco · magnitude 9.9 · 4.7′ × 1.9′ · best in Apr, May, Jun. 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 ZWO Seestar S30 Pro
The S30 optics upgraded to a quadruplet in front of an 8 MP IMX585. Same speed per pixel as the S30, four times the pixels, so you can crop hard.
10, 20 and 30 s in Alt-Az; 60 s only in EQ mode, which needs the TH10 head. Built-in UV/IR-cut, dual-band (OIII 30 nm / Hα 20 nm) and dark filters on the telephoto camera.
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 60 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 Spindle Galaxy from a Seestar S30 Pro? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- Spindle Galaxy with the ZWO Seestar S50: 24 min from Bortle 6
- Spindle Galaxy with the ZWO Seestar S50 Pro: 26 min from Bortle 6
- Spindle Galaxy with the ZWO Seestar S30: 25 min from Bortle 6
- Spindle Galaxy with the DwarfLab DWARF 3: 35 min from Bortle 6
- Spindle Galaxy with the DwarfLab DWARF mini: 23 min from Bortle 6
- Spindle Galaxy with the DwarfLab Draco: 19 min from Bortle 6
- Spindle Galaxy with the DwarfLab DWARF II: 1 h 18 min from Bortle 6
- Spindle Galaxy with the Vaonis Vespera II: 24 min from Bortle 6
- Spindle Galaxy with the Vaonis Vespera Pro: 52 min from Bortle 6
- Spindle Galaxy with the Vaonis Vespera 3: 23 min from Bortle 6
- Spindle Galaxy with the Vaonis Vespera Pro 2: 50 min from Bortle 6
- Spindle Galaxy with the Unistellar eQuinox 2: 20 min from Bortle 6
- Spindle Galaxy with the Unistellar Odyssey: 1 h 32 min from Bortle 6
- Spindle Galaxy with the Celestron Origin: 6 min from Bortle 6
- Spindle Galaxy with the Celestron Origin Mark II: 9 min from Bortle 6
All telescopes for the Spindle Galaxy · All targets for the Seestar S30 Pro