When is the best time to observe Theta Microscopii?

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

Where is Theta Microscopii located in the sky?

Theta Microscopii lies in the constellation Microscopium at right ascension 21h 24m and declination -41° 00′.

What telescope do I need to split Theta Microscopii?

Splitting Theta Microscopii requires an aperture of roughly 200 mm or larger — the components are separated by about 0.3″ at magnitudes near 5.8. Larger apertures and steady seeing help resolve the pair cleanly.

Theta Microscopii — Double Star in Microscopium

HIP 105696; Theta2 Microscopii

Magnitude 5.8^m DoubleStar Microscopium (Mic) Visible

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Observe

1Physical Properties

Magnitude 5.77

Spectral Type A0IIIpSi bright giant

Star Color Blue-white (B-V -0.05)

Distance 544 ly

2Position & Identifiers

RA 21h 24m 24.8s

Dec -41° 00' 24.0"

Constellation Microscopium (Mic)

HR 8180

HIP 105696

HD 203585

SAO 230667

Bayer Theta2

SIMBAD Wikipedia

3How easy to spot?

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Equipment	Bortle 3	Bortle 4	Bortle 5
Naked eye Naked eye	Hard+	Hard	V. hard+
50 mm finder 50mm finder	Easy	Easy	Easy
150 mm telescope 150mm scope	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 AB

Separation 0.3″

Companion Mag 6.9

Position Angle 169°

Star Colors A: Blue-white B: White

Discoverer BU 766

Separation over time

Measured 1879 → 2021 (142 y)

Separation drift 0.80" → 0.30" (-0.50")

Rate -0.0035" / y

PA drift 314° → 169° (-145°, -1.021°/y)

Slow change over generations — observable in lifetime comparisons.

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.