When is the best time to observe HIP 91532?

HIP 91532 is best observed from May through July, with peak visibility during June when it transits around midnight in the Northern Hemisphere.

Where is HIP 91532 located in the sky?

HIP 91532 lies in the constellation Scutum at right ascension 18h 40m and declination -07° 47′.

What telescope do I need to split HIP 91532?

Splitting HIP 91532 requires an aperture of roughly 60 mm or larger — the components are separated by about 16.4″ at magnitudes near 5.8. The companion is about 6.1 magnitudes fainter, so glare from the primary — not separation — sets the minimum aperture. Larger apertures and steady seeing help resolve the pair cleanly.

HIP 91532 — Double Star in Scutum

Magnitude 5.8^m DoubleStar Scutum (Sct) Visible

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Observe

1Physical Properties

Magnitude 5.84

Spectral Type K4III giant

Star Color Red (B-V 1.55)

2Position & Identifiers

RA 18h 40m 00.5s

Dec -07° 47' 26.0"

Constellation Scutum (Sct)

HR 7007

HIP 91532

HD 172348

SAO 142480

Double Cat 11552

SIMBAD

3How easy to split?

Primary 5.8 mag Companion 11.9 mag Separation 16.4″

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

Easy Medium Hard Very hard Impossible

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

4Visibility

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Best season May – Jul (peak: Jun)

5Multiple Star System

Separation 16.4″

Companion Mag 11.9

Position Angle 191°

Star Colors A: Red

Discoverer STF2350

Notes

Optical.

Separation over time

Measured 1848 → 2020 (172 y)

Separation drift 24.5" → 16.4" (-8.10")

Rate -0.0471" / y

PA drift 195° → 191° (-4°, -0.023°/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.