When is the best time to observe Xi Hydrae?

Xi Hydrae is best observed from February through April, with peak visibility during March when it transits around midnight in the Northern Hemisphere.

Where is Xi Hydrae located in the sky?

Xi Hydrae lies in the constellation Hydra at right ascension 11h 33m and declination -31° 51′.

What telescope do I need to split Xi Hydrae?

Splitting Xi Hydrae requires an aperture of roughly 60 mm or larger — the components are separated by about 74.6″ at magnitudes near 3.5. The companion is about 7.2 magnitudes fainter, so glare from the primary — not separation — sets the minimum aperture. Larger apertures and steady seeing help resolve the pair cleanly.

Xi Hydrae — Double Star in Hydra

Magnitude 3.5^m DoubleStar Hydra (Hya) Visible

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1Physical Properties

Magnitude 3.54

Spectral Type G7III giant

Star Color Orange (B-V 0.94)

Distance 130 ly

2Position & Identifiers

RA 11h 33m 00.1s

Dec -31° 51' 28.0"

Constellation Hydra (Hya)

HR 4450

HIP 56343

HD 100407

SAO 202558

Bayer Xi

SIMBAD

3How easy to split?

Primary 3.5 mag Companion 10.7 mag Separation 74.6″

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

Easy Medium Hard Very hard Impossible

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

4Visibility

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Best season Feb – Apr (peak: Mar)

5Multiple Star System

Separation 74.6″

Companion Mag 10.7

Position Angle 134°

Star Colors A: Orange

Discoverer HJ 4449

Separation over time

Measured 1834 → 2015 (181 y)

Separation drift 60.0" → 74.6" (+14.60")

Rate +0.0807" / y

PA drift 170° → 134° (-36°, -0.199°/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.