How long to image the Andromeda Galaxy with the ZWO Seestar S50 Pro
From a Bortle 6 suburban sky, the ZWO Seestar S50 Pro needs about 1 h 36 min (575 subs of 10 s) for a solid image of the Andromeda Galaxy. A quick look takes 24 min; a showpiece 6 h 23 min. Under a Bortle 3 rural sky the solid figure drops to 38 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 is 2.1× wider than the frame.
| Sky | Quick lookTarget obvious, still noisy | SolidClean enough to share | ShowpieceSmooth faint detail, print-worthy |
|---|---|---|---|
| Bortle 1Excellent dark site | 8 min49 subs | 32 min193 subs | 2 h 08 min771 subs |
| Bortle 2Typical dark site | 9 min52 subs | 34 min205 subs | 2 h 16 min818 subs |
| Bortle 3Rural | 9 min57 subs | 38 min227 subs | 2 h 31 min907 subs |
| Bortle 4Rural / suburban transition | 12 min71 subs | 47 min281 subs | 3 h 07 min1,121 subs |
| Bortle 5Suburban | 15 min92 subs | 1 h 01 min366 subs | 4 h 04 min1,462 subs |
| Bortle 6Bright suburban | 24 min144 subs | 1 h 36 min575 subs | 6 h 23 min2,297 subs |
| Bortle 7Suburban / urban transition | 41 min244 subs | 2 h 42 min973 subs | 11 h3,889 subs |
| Bortle 8City | 1 h 06 min398 subs | 4 h 25 min1,590 subs | 18 h6,360 subs |
| Bortle 9Inner city | 2 h 01 min727 subs | 8 h 05 min2,908 subs | 32 h11,630 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 2 h 04 min of run time. The Seestar S50 Pro’s battery (rated about 9 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 PD power bank 20000mAh 30WAccepts 12 V 3 A PD, so a 30 W bank tops up the 10,000 mAh cell while imaging.
- Seestar S50 Pro dew shieldDew heater is built in; a shield adds margin on damp nights. Check the listing says S50 Pro.
- 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 S50 Pro →
How it frames
The Andromeda Galaxy is 178′ × 63′ across. The Seestar S50 Pro frames 2.45° × 1.38° at 2.30″ per pixel, so it is 2.1× wider than the frame. A mosaic, or choosing the part you want and letting the rest go, is how it gets shot on this scope.
Longer subs
10, 20 and 30 s in Alt-Az; 60 s only in EQ mode, and 60 s is the ceiling. Time for a solid image by sub length:
| Sub length | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| 10 s | 38 min227 subs | 1 h 01 min366 subs | 2 h 42 min973 subs |
| 20 s | 32 min96 subs | 55 min166 subs | 2 h 36 min469 subs |
| 30 s | 30 min60 subs | 53 min107 subs | 2 h 34 min309 subs |
| 60 s | 30 min30 subs | 51 min52 subs | 2 h 32 min153 subs |
Leave the dual-band filter out for the Andromeda 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 Andromeda Galaxy
The nearest big spiral and the most imaged galaxy in the sky. The core arrives in minutes, the dust lanes in an hour, the faint outer disc needs a whole night. Too big for most smart-scope fields without mosaic.
M31, NGC 224 · Galaxy in Andromeda · magnitude 3.4 · 178′ × 63′ · best in Sep, Oct, Nov. 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 S50 Pro
The S50 optics at 260 mm on an 8 MP 1/1.2-inch sensor: a wider, taller field, four times the pixels, and 60 s subs in EQ mode. Per pixel it is a whisker slower than the S50 because of the longer focal length; the long subs make it the better dark-site scope.
10, 20 and 30 s in Alt-Az; 60 s only in EQ mode, and 60 s is the ceiling. 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 Andromeda Galaxy from a Seestar S50 Pro? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- Andromeda Galaxy with the ZWO Seestar S50: 1 h 27 min from Bortle 6
- Andromeda Galaxy with the ZWO Seestar S30: 1 h 32 min from Bortle 6
- Andromeda Galaxy with the ZWO Seestar S30 Pro: 1 h 41 min from Bortle 6
- Andromeda Galaxy with the DwarfLab DWARF 3: 2 h 07 min from Bortle 6
- Andromeda Galaxy with the DwarfLab DWARF mini: 1 h 27 min from Bortle 6
- Andromeda Galaxy with the DwarfLab Draco: 1 h 12 min from Bortle 6
- Andromeda Galaxy with the DwarfLab DWARF II: 4 h 59 min from Bortle 6
- Andromeda Galaxy with the Vaonis Vespera II: 1 h 27 min from Bortle 6
- Andromeda Galaxy with the Vaonis Vespera Pro: 3 h 16 min from Bortle 6
- Andromeda Galaxy with the Vaonis Vespera 3: 1 h 24 min from Bortle 6
- Andromeda Galaxy with the Vaonis Vespera Pro 2: 3 h 07 min from Bortle 6
- Andromeda Galaxy with the Unistellar eQuinox 2: 1 h 19 min from Bortle 6
- Andromeda Galaxy with the Unistellar Odyssey: 6 h 07 min from Bortle 6
- Andromeda Galaxy with the Celestron Origin: 23 min from Bortle 6
- Andromeda Galaxy with the Celestron Origin Mark II: 32 min from Bortle 6
All telescopes for the Andromeda Galaxy · All targets for the Seestar S50 Pro