How long to image the Pelican Nebula with the ZWO Seestar S30

From a Bortle 6 suburban sky, the ZWO Seestar S30 needs about 2 h 20 min (843 subs of 10 s with the built-in dual-band (LP filter) filter) for a solid image of the Pelican Nebula. A quick look takes 35 min; a showpiece 9 h 22 min. Under a Bortle 3 rural sky the solid figure drops to 1 h 43 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it fills 84% of the frame’s short side.

Pelican Nebula with the ZWO Seestar S30: 10 s subs with the built-in dual-band (LP filter) filter.
SkyQuick lookTarget obvious, still noisySolidClean enough to shareShowpieceSmooth faint detail, print-worthy
Bortle 1Excellent dark site25 min150 subs1 h 39 min597 subs6 h 38 min2,386 subs
Bortle 2Typical dark site25 min151 subs1 h 41 min604 subs6 h 43 min2,416 subs
Bortle 3Rural26 min155 subs1 h 43 min619 subs6 h 52 min2,473 subs
Bortle 4Rural / suburban transition27 min164 subs1 h 49 min653 subs7 h 15 min2,612 subs
Bortle 5Suburban29 min177 subs1 h 58 min708 subs7 h 52 min2,831 subs
Bortle 6Bright suburban35 min211 subs2 h 20 min843 subs9 h 22 min3,370 subs
Bortle 7Suburban / urban transition46 min275 subs3 h 03 min1,099 subs12 h4,396 subs
Bortle 8City1 h 02 min375 subs4 h 10 min1,498 subs17 h5,990 subs
Bortle 9Inner city1 h 38 min587 subs6 h 31 min2,348 subs26 h9,389 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 3 h 03 min of run time. The Seestar S30’s battery (rated about 6 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.)

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How it frames

The Pelican Nebula is 60′ × 50′ across. The Seestar S30 frames 2.13° × 1.20° at 3.99″ per pixel, so it fills 84% 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 lengthBortle 3Bortle 5Bortle 7
10 s1 h 43 min619 subs1 h 58 min708 subs3 h 03 min1,099 subs
20 s1 h 09 min209 subs1 h 24 min254 subs2 h 30 min449 subs
30 s58 min117 subs1 h 13 min147 subs2 h 18 min277 subs
60 s47 min48 subs1 h 02 min63 subs2 h 07 min128 subs

With and without the dual-band filter

Solid quality, default sub length.
FilterBortle 3Bortle 5Bortle 7
UV/IR-cut (no light-pollution filter)1 h 21 min489 subs2 h 10 min781 subs5 h 43 min2,060 subs
dual-band (LP filter)1 h 43 min619 subs1 h 58 min708 subs3 h 03 min1,099 subs

About the Pelican Nebula

The North America Nebula's neighbour across a dark gulf, with pillars along its beak. Fainter than NGC 7000 and worth its own session.

IC 5070 · Emission nebula in Cygnus · magnitude 8.0 · 60′ × 50′ · best in Jul, Aug, Sep. Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.

Emission nebulae glow in a few narrow lines, mostly hydrogen-alpha (deep red) and doubly ionised oxygen (teal). A dual-band filter passes those lines and blocks most skyglow, which is why it cuts the time needed from a suburban sky so dramatically. Use it. From a genuinely dark site the gain is smaller because there is less skyglow to block, and read noise becomes the limit, which is where longer subs (EQ mode, or Expert Mode on a Vespera) earn their keep.

Stars lose colour through a dual-band filter; a short broadband stack blended in fixes that if you care.

About the ZWO Seestar S30

Wider and lighter than the S50 with the same 2.9 µm pixels, so its per-pixel speed on extended targets is close despite the smaller aperture. Ideal for big nebulae.

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.

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.

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Imaged the Pelican Nebula with your Seestar S30? Did the solid figure match?Anonymous, one tap. It is how the model gets calibrated.

Have an image of the Pelican Nebula from a Seestar S30? Email it with your total time and sky to [email protected] and it goes here, credited.

Same target, other telescopes

All telescopes for the Pelican Nebula · All targets for the Seestar S30