When is the best time to observe HIP 36640?

HIP 36640 is best observed from December through February, with peak visibility during January when it transits around midnight in the Northern Hemisphere.

Where is HIP 36640 located in the sky?

HIP 36640 lies in the constellation Monoceros at right ascension 07h 32m and declination -08° 53′.

What telescope do I need to split HIP 36640?

Splitting HIP 36640 requires an aperture of roughly 60 mm or larger — the components are separated by about 23.9″ at magnitudes near 5.9. Larger apertures and steady seeing help resolve the pair cleanly.

HIP 36640 — Double Star in Monoceros

Observable Double Star Good (58/100)

Sep: 23.9", Companion: mag 8.7

Magnitude 5.9^m DoubleStar Monoceros (Mon) Visible

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Observe

1Physical Properties

Magnitude 5.90

Spectral Type F5V

Star Color Yellow-white (B-V 0.54)

2Position & Identifiers

RA 07h 32m 05.8s

Dec -08° 52' 51.0"

Constellation Monoceros (Mon)

HR 2883

HIP 36640

HD 59984

SAO 134806

Double Cat 6158

SIMBAD

3How easy to split?

Primary 5.9 mag Companion 8.7 mag Separation 23.9″

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Telescope	Bortle 3	Bortle 4	Bortle 5
80 mm refractor 80mm refr.	Easy	Easy	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 Dec – Feb (peak: Jan)

5Multiple Star System

Separation 23.9″

Companion Mag 8.7

Position Angle 113°

Star Colors A: Yellow-white B: Orange

Discoverer STF1112

Notes

CPM?

Separation over time

Measured 1831 → 2020 (189 y)

Separation drift 23.0" → 23.9" (+0.90")

Rate +0.0048" / y

PA drift 117° → 113° (-4°, -0.021°/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.