When is the best time to observe Nu Telescopii?

Nu Telescopii is best observed from June through August, with peak visibility during July when it transits around midnight in the Northern Hemisphere.

Where is Nu Telescopii located in the sky?

Nu Telescopii lies in the constellation Telescopium at right ascension 19h 48m and declination -56° 22′.

What telescope do I need to split Nu Telescopii?

Splitting Nu Telescopii requires an aperture of roughly 60 mm or larger — the components are separated by about 102.0″ at magnitudes near 5.3. The companion is about 4.0 magnitudes fainter, so glare from the primary — not separation — sets the minimum aperture. Larger apertures and steady seeing help resolve the pair cleanly.

Nu Telescopii — Double Star in Telescopium

Magnitude 5.3^m DoubleStar Telescopium (Tel) Visible

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Observe

1Physical Properties

Magnitude 5.35

Spectral Type A7III-IV giant

Star Color Yellow-white (B-V 0.20)

2Position & Identifiers

RA 19h 48m 01.2s

Dec -56° 21' 45.0"

Constellation Telescopium (Tel)

HR 7510

HIP 97421

HD 186543

SAO 246271

Bayer Nu

SIMBAD

3How easy to split?

Primary 5.4 mag Companion 9.3 mag Separation 102.0″

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Telescope	Bortle 3	Bortle 4	Bortle 5
80 mm refractor 80mm refr.	Easy	Medium+	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 Jun – Aug (peak: Jul)

5Multiple Star System

Separation 102.0″

Companion Mag 9.3

Position Angle 333°

Star Colors A: Yellow-white B: Orange

Discoverer TOK 335

Separation over time

Measured 1893 → 2015 (122 y)

Separation drift 102.5" → 102.0" (-0.50")

Rate -0.0041" / y

PA drift 334° → 333° (-1°, -0.008°/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.