When is the best time to observe Theta Reticuli?

Theta Reticuli is best observed from October through December, with peak visibility during November when it transits around midnight in the Northern Hemisphere.

Where is Theta Reticuli located in the sky?

Theta Reticuli lies in the constellation Reticulum at right ascension 04h 18m and declination -63° 15′.

What telescope do I need to split Theta Reticuli?

Splitting Theta Reticuli requires an aperture of roughly 100 mm or larger — the components are separated by about 4.1″ at magnitudes near 5.9. Larger apertures and steady seeing help resolve the pair cleanly.

Theta Reticuli — Double Star in Reticulum

Observable Double Star Good (53/100)

Sep: 4.1", Companion: mag 7.7

Magnitude 5.9^m DoubleStar Reticulum (Ret) Visible

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Observe

1Physical Properties

Magnitude 5.87

Spectral Type B9III-IV giant

Star Color Blue-white (B-V -0.07)

2Position & Identifiers

RA 04h 17m 40.2s

Dec -63° 15' 20.0"

Constellation Reticulum (Ret)

HR 1372

HIP 20020

HD 27657

SAO 248986

Bayer Theta

SIMBAD

3How easy to split?

Primary 5.9 mag Companion 7.7 mag Separation 4.1″

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Telescope	Bortle 3	Bortle 4	Bortle 5
80 mm refractor 80mm refr.	Medium+	Medium+	Medium+
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 Oct – Dec (peak: Nov)

5Multiple Star System

Separation 4.1″

Companion Mag 7.7

Position Angle 2°

Star Colors A: Blue-white B: Yellow-white

Discoverer RMK 3

Separation over time

Measured 1835 → 2015 (180 y)

Separation drift 6.4" → 4.1" (-2.30")

Rate -0.0128" / y

PA drift 6° → 2° (-4°, -0.022°/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.