When is the best time to observe HIP 21323?

HIP 21323 is best observed from October through December, with peak visibility during November when it transits around midnight in the Northern Hemisphere.

Where is HIP 21323 located in the sky?

HIP 21323 lies in the constellation Taurus at right ascension 04h 35m and declination +28° 58′.

What telescope do I need to split HIP 21323?

Splitting HIP 21323 requires an aperture of roughly 60 mm or larger — the components are separated by about 25.3″ at magnitudes near 5.9. The companion is about 4.4 magnitudes fainter, so glare from the primary — not separation — sets the minimum aperture. Larger apertures and steady seeing help resolve the pair cleanly.

HIP 21323 — Double Star in Taurus

Magnitude 5.9^m DoubleStar Taurus (Tau) Visible

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Observe

1Physical Properties

Magnitude 5.88

Spectral Type B9pHg

Star Color Blue-white (B-V -0.06)

2Position & Identifiers

RA 04h 34m 38.0s

Dec +28° 57' 40.0"

Constellation Taurus (Tau)

HR 1445

HIP 21323

HD 28929

SAO 76654

Double Cat 3304

SIMBAD

3How easy to split?

Primary 5.9 mag Companion 10.3 mag Separation 25.3″

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Telescope	Bortle 3	Bortle 4	Bortle 5
80 mm refractor 80mm refr.	Medium	Medium	Hard+
150 mm Newton 150mm Newt.	Easy	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 Oct – Dec (peak: Nov)

5Multiple Star System Triple

Components 3 (triple)

Component IDs AB

Separation 25.3″

Companion Mag 10.3

Position Angle 102°

Star Colors A: Blue-white B: Yellow

Discoverer HJ 5461

Separation over time

Measured 1827 → 2016 (189 y)

Separation drift 30.0" → 25.3" (-4.70")

Rate -0.0249" / y

PA drift 100° → 102° (+2°, +0.011°/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.