When is the best time to observe HIP 20109?

HIP 20109 is best observed from October through December, with peak visibility during November when it transits around midnight in the Northern Hemisphere.

Where is HIP 20109 located in the sky?

HIP 20109 lies in the constellation Dorado at right ascension 04h 19m and declination -52° 52′.

What telescope do I need to split HIP 20109?

Splitting HIP 20109 requires an aperture of roughly 60 mm or larger — the components are separated by about 270.4″ at magnitudes near 6.1. Larger apertures and steady seeing help resolve the pair cleanly.

HIP 20109 — Double Star in Dorado

Magnitude 6.1^m DoubleStar Dorado (Dor) Visible

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Observe

1Physical Properties

Magnitude 6.09

Spectral Type F7IV-V subgiant

Star Color Yellow (B-V 0.49)

2Position & Identifiers

RA 04h 18m 40.0s

Dec -52° 51' 36.0"

Constellation Dorado (Dor)

HR 1365

HIP 20109

HD 27604

SAO 233476

SIMBAD

3How easy to split?

Primary 6.1 mag Companion 7.8 mag Separation 270.4″

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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 Oct – Dec (peak: Nov)

5Multiple Star System

Separation 270.4″

Companion Mag 7.8

Companion Sp F5V

Position Angle 236°

Star Colors A: Yellow B: Yellow-white

Discoverer SHY 462

Separation over time

Measured 1908 → 2016 (108 y)

Separation drift 270.4" → 270.4" (+0.00")

Rate +0.0000" / y

PA drift 236° → 236° (+0°, +0.000°/y)

Essentially fixed on human timescales — the same view your grandchildren will see.

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.