When is the best time to observe Eta Microscopii?

Eta Microscopii is best observed from July through September, with peak visibility during August when it transits around midnight in the Northern Hemisphere.

Where is Eta Microscopii located in the sky?

Eta Microscopii lies in the constellation Microscopium at right ascension 21h 06m and declination -41° 23′.

What telescope do I need to split Eta Microscopii?

Splitting Eta Microscopii requires an aperture of roughly 60 mm or larger — the components are separated by about 127.8″ at magnitudes near 5.5. Larger apertures and steady seeing help resolve the pair cleanly.

Eta Microscopii — Double Star in Microscopium

Observable Double Star Good (50/100)

Sep: 127.8", Companion: mag 7.9

DoubleStar Microscopium (Mic) Visible

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Observe

1Physical Properties

Magnitude 5.53

Spectral Type K3III

Star Color Red (B-V 1.35)

2Position & Identifiers

RA 21h 06m 25.5s

Dec -41° 23' 10.0"

Constellation Microscopium (Mic)

HR 8069

HIP 104177

HD 200702

Bayer Eta

SIMBAD

3How easy to split?

Primary 5.5 mag Companion 7.9 mag Separation 127.8″

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Telescope	Bortle 3	Bortle 4	Bortle 5
80 mm refractor 80mm refr.	Easy	Easy	Easy
150 mm Newton 150mm Newt.	Easy	Easy	Easy
Celestron C8 (203 mm SCT) C8 203mm	Easy	Easy	Easy

Easy Medium Hard Very hard Impossible

Bortle 3 = rural · 4 = outer suburbs · 5 = suburbs

4Visibility

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Best season Jul – Sep (peak: Aug)

5Multiple Star System Triple C: optical

Components 3 (triple)

Component IDs AC

Separation 127.8″

Companion Mag 7.9

Position Angle 88°

Star Colors A: Red

Discoverer SEE 437

Separation over time

Measured 1879 → 2013 (134 y)

Separation drift 132.9" → 127.8" (-5.10")

Rate -0.0381" / y

PA drift 88° → 88° (+0°, +0.000°/y)

Apparent motion is significant on a human timescale — worth revisiting in a decade.

Measured from the WDS observational archive. No orbital solution has been derived — most likely the period is too long to fit an orbit to the available measurement arc.