When is the best time to observe HIP 91369?

HIP 91369 is best observed from May through July, with peak visibility during June when it transits around midnight in the Northern Hemisphere.

Where is HIP 91369 located in the sky?

HIP 91369 lies in the constellation Scutum at right ascension 18h 38m and declination -14° 00′.

What telescope do I need to split HIP 91369?

Splitting HIP 91369 requires an aperture of roughly 210 mm or larger — the components are separated by about 2.5″ at magnitudes near 6.5. The companion is about 4.1 magnitudes fainter, so glare from the primary — not separation — sets the minimum aperture. Larger apertures and steady seeing help resolve the pair cleanly.

HIP 91369 — Double Star in Scutum

Magnitude 6.5^m DoubleStar Scutum (Sct) Visible

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Observe

1Physical Properties

Magnitude 6.47

Spectral Type B9IV subgiant

Star Color Yellow-white (B-V 0.21)

2Position & Identifiers

RA 18h 38m 04.6s

Dec -14° 00' 17.0"

Constellation Scutum (Sct)

HR 6989

HIP 91369

HD 171957

SAO 161687

Double Cat 11512

SIMBAD

3How easy to split?

Primary 6.5 mag Companion 10.6 mag Separation 2.5″

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

Easy Medium Hard Very hard Impossible

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

To reach "Medium" at Bortle 3, you'd need at least a 210 mm reflector.

4Visibility

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Best season May – Jul (peak: Jun)

5Multiple Star System Triple B,D,F,G: optical

Components 3 (triple)

Component IDs AB

Separation 2.5″

Companion Mag 10.6

Position Angle 189°

Star Colors A: Yellow-white B: Orange

Discoverer BU 135

Notes

AB, fixed sep.

Separation over time

Measured 1873 → 2015 (142 y)

Separation drift 2.0" → 2.5" (+0.50")

Rate +0.0035" / y

PA drift 210° → 189° (-21°, -0.148°/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.