When is the best time to observe HIP 66400?

HIP 66400 is best observed from March through May, with peak visibility during April when it transits around midnight in the Northern Hemisphere.

Where is HIP 66400 located in the sky?

HIP 66400 lies in the constellation Hydra at right ascension 13h 37m and declination -26° 30′.

What telescope do I need to split HIP 66400?

Splitting HIP 66400 requires an aperture of roughly 60 mm or larger — the components are separated by about 10.2″ at magnitudes near 5.8. Larger apertures and steady seeing help resolve the pair cleanly.

HIP 66400 — Double Star in Hydra

Observable Double Star Excellent (69/100)

Sep: 10.2", Companion: mag 6.6

Magnitude 5.8^m DoubleStar Hydra (Hya) Visible

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Observe

1Physical Properties

Magnitude 5.78

Spectral Type A7III giant

Star Color Yellow-white (B-V 0.22)

Distance 155 ly

2Position & Identifiers

RA 13h 36m 48.4s

Dec -26° 29' 42.0"

Constellation Hydra (Hya)

HR 5120

HIP 66400

HD 118349

SAO 181790

Double Cat 8966

SIMBAD

3How easy to split?

Primary 5.8 mag Companion 6.6 mag Separation 10.2″

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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 Mar – May (peak: Apr)

5Multiple Star System Quadruple C,D: optical

Components 4 (quadruple)

Component IDs AB

Separation 10.2″

Companion Mag 6.6

Companion Sp A7IV

Position Angle 190°

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

Discoverer H N 69

Notes

AB binary. B is A7IV.

Separation over time

Measured 1825 → 2015 (190 y)

Separation drift 10.4" → 10.2" (-0.20")

Rate -0.0011" / y

PA drift 193° → 190° (-3°, -0.016°/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.