How long to image the Flame Nebula with the ZWO Seestar S30 Pro

From a Bortle 6 suburban sky, the ZWO Seestar S30 Pro needs about 38 min (229 subs of 10 s with the built-in dual-band (LP filter) filter) for a solid image of the Flame Nebula. A quick look takes 10 min; a showpiece 2 h 32 min. Under a Bortle 3 rural sky the solid figure drops to 28 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it fills 22% of the frame’s short side.

Flame Nebula with the ZWO Seestar S30 Pro: 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 site7 min41 subs27 min164 subs1 h 49 min656 subs
Bortle 2Typical dark site7 min42 subs28 min166 subs1 h 51 min664 subs
Bortle 3Rural7 min43 subs28 min170 subs1 h 53 min679 subs
Bortle 4Rural / suburban transition7 min45 subs30 min179 subs1 h 59 min715 subs
Bortle 5Suburban8 min49 subs32 min193 subs2 h 09 min772 subs
Bortle 6Bright suburban10 min58 subs38 min229 subs2 h 32 min913 subs
Bortle 7Suburban / urban transition12 min74 subs49 min295 subs3 h 17 min1,180 subs
Bortle 8City17 min100 subs1 h 06 min399 subs4 h 26 min1,596 subs
Bortle 9Inner city26 min156 subs1 h 43 min621 subs6 h 54 min2,482 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 49 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, and 30% off the battery for a December night.)

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How it frames

The Flame Nebula is 30′ across. The Seestar S30 Pro frames 3.99° × 2.24° at 3.74″ per pixel, so it fills 22% 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 s28 min170 subs32 min193 subs49 min295 subs
20 s21 min65 subs25 min76 subs42 min127 subs
30 s19 min39 subs23 min46 subs40 min80 subs
60 s30 min30 subs30 min30 subs38 min38 subs

With and without the dual-band filter

Solid quality, default sub length.
FilterBortle 3Bortle 5Bortle 7
UV/IR-cut (no light-pollution filter)23 min138 subs36 min214 subs1 h 31 min547 subs
dual-band (LP filter)28 min170 subs32 min193 subs49 min295 subs

About the Flame Nebula

A bright emission nebula beside Alnitak, split by a dark lane like a tree. Alnitak's glare is the main problem; keep it out of the frame if you can.

NGC 2024 · Emission nebula in Orion · magnitude 10.0 · 30′ · best in Nov, Dec, Jan. 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 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.

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

Have an image of the Flame Nebula 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

All telescopes for the Flame Nebula · All targets for the Seestar S30 Pro