How long to image the M62 with the ZWO Seestar S30 Pro

From a Bortle 6 suburban sky, the ZWO Seestar S30 Pro needs about 10 min (58 subs of 10 s) for a solid image of the M62. A quick look takes 2 min; a showpiece 38 min. Under a Bortle 3 rural sky the solid figure drops to 5 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 11% of the frame’s short side.

M62 with the ZWO Seestar S30 Pro: 10 s subs.
SkyQuick lookTarget obvious, still noisySolidClean enough to shareShowpieceSmooth faint detail, print-worthy
Bortle 1Excellent dark site2 min10 subs5 min30 subs18 min107 subs
Bortle 2Typical dark site2 min10 subs5 min30 subs18 min110 subs
Bortle 3Rural2 min10 subs5 min30 subs19 min117 subs
Bortle 4Rural / suburban transition2 min10 subs6 min34 subs22 min135 subs
Bortle 5Suburban2 min11 subs7 min41 subs27 min162 subs
Bortle 6Bright suburban2 min15 subs10 min58 subs38 min230 subs
Bortle 7Suburban / urban transition4 min23 subs15 min90 subs1 h358 subs
Bortle 8City6 min35 subs23 min140 subs1 h 33 min557 subs
Bortle 9Inner city10 min62 subs41 min246 subs2 h 44 min983 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 12 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.)

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How it frames

The M62 is 15′ across. The Seestar S30 Pro frames 3.99° × 2.24° at 3.74″ per pixel, so it fills 11% 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 s5 min30 subs7 min41 subs15 min90 subs
20 s10 min30 subs10 min30 subs14 min44 subs
30 s15 min30 subs15 min30 subs15 min30 subs
60 s30 min30 subs30 min30 subs30 min30 subs

Leave the dual-band filter out for the M62. It is a globular cluster, 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 11 times slower.

About the M62

A bright but lopsided globular near the galactic centre, low from northern latitudes.

NGC 6266 · Globular cluster in Ophiuchus · magnitude 6.5 · 15′ · best in May, Jun, Jul. Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.

Globular clusters are point sources packed tight, so they come quickly: the core resolves into stars within a handful of minutes on any smart scope. More time deepens the halo and pulls in the faint outer members. Use short subs so the core does not saturate into a white blob, and no filter.

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 M62 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 M62 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 M62 · All targets for the Seestar S30 Pro