How long to image the M58 with the Unistellar eQuinox 2

From a Bortle 6 suburban sky, the Unistellar eQuinox 2 needs about 2 h 21 min (2,119 subs of 4 s) for a solid image of the M58. A quick look takes 35 min; a showpiece 9 h 25 min. Under a Bortle 3 rural sky the solid figure drops to 1 h 22 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it fills 18% of the frame’s short side.

M58 with the Unistellar eQuinox 2: 4 s subs.
SkyQuick lookTarget obvious, still noisySolidClean enough to shareShowpieceSmooth faint detail, print-worthy
Bortle 1Excellent dark site19 min287 subs1 h 17 min1,148 subs5 h 06 min4,591 subs
Bortle 2Typical dark site20 min295 subs1 h 18 min1,178 subs5 h 14 min4,710 subs
Bortle 3Rural21 min309 subs1 h 22 min1,234 subs5 h 29 min4,936 subs
Bortle 4Rural / suburban transition23 min343 subs1 h 31 min1,371 subs6 h 05 min5,482 subs
Bortle 5Suburban26 min397 subs1 h 46 min1,587 subs7 h 03 min6,348 subs
Bortle 6Bright suburban35 min530 subs2 h 21 min2,119 subs9 h 25 min8,473 subs
Bortle 7Suburban / urban transition52 min783 subs3 h 29 min3,131 subs14 h12,521 subs
Bortle 8City1 h 18 min1,176 subs5 h 13 min4,702 subs21 h18,807 subs
Bortle 9Inner city2 h 14 min2,014 subs8 h 57 min8,054 subs36 h32,213 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 3 h 04 min of run time. The eQuinox 2’s battery (rated about 11 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 M58 is 6′ × 5′ across. The eQuinox 2 frames 0.76° × 0.57° at 1.33″ per pixel, so it fills 18% of the frame’s short side.

About the M58

A barred spiral in the Virgo cluster, one of the brighter members. Frame it with M59 and M60.

NGC 4579 · Galaxy in Virgo · magnitude 9.7 · 6′ × 5′ · best in Mar, Apr, May. 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 Unistellar eQuinox 2

A 114 mm Newtonian with five times the light grasp of a 50 mm refractor. Fixed 4 s subs put it in read-noise territory under dark skies, but the aperture carries it. The published field is 45.6′ × 34.2′, a crop of the sensor.

Fixed 4 s subs in Enhanced Vision; they cannot be changed. No built-in filter. Unistellar sells only a solar filter and says a third-party filter is at your own risk and voids the warranty.

The eQuinox 2 uses fixed 4 s subs, so the only levers you have are the sky you shoot from, the filter, and total time.

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 M58 with your eQuinox 2? Did the solid figure match?Anonymous, one tap. It is how the model gets calibrated.

Have an image of the M58 from a eQuinox 2? Email it with your total time and sky to [email protected] and it goes here, credited.

Same target, other telescopes

All telescopes for the M58 · All targets for the eQuinox 2