When is the best time to observe HIP 91820?

HIP 91820 is best observed from May through July, with peak visibility during June when it transits around midnight in the Northern Hemisphere.

Where is HIP 91820 located in the sky?

HIP 91820 lies in the constellation Lyra at right ascension 18h 43m and declination +39° 18′.

What telescope do I need to split HIP 91820?

Splitting HIP 91820 requires an aperture of roughly 60 mm or larger — the components are separated by about 60.8″ at magnitudes near 6.5. The companion is about 3.9 magnitudes fainter, so glare from the primary — not separation — sets the minimum aperture. Larger apertures and steady seeing help resolve the pair cleanly.

HIP 91820 — Double Star in Lyra

Magnitude 6.5^m DoubleStar Lyra (Lyr) Visible

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Observe

1Physical Properties

Magnitude 6.45

Spectral Type K5

Star Color Red (B-V 1.59) (reddened by dust)

2Position & Identifiers

RA 18h 43m 16.7s

Dec +39° 18' 01.0"

Constellation Lyra (Lyr)

HR 7041

HIP 91820

HD 173383

SAO 67287

SIMBAD

3How easy to split?

Primary 6.5 mag Companion 10.4 mag Separation 60.8″

Telescope	Bortle 3	Bortle 4	Bortle 5
80 mm refractor 80mm refr.	Medium	Hard+	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

Set a location in User Settings to see visibility data.

Best season May – Jul (peak: Jun)

5Multiple Star System

Separation 60.8″

Companion Mag 10.3

Position Angle 192°

Star Colors A: Red (reddened by dust)

Discoverer BLL 35

Separation over time

Measured 1877 → 2015 (138 y)

Separation drift 60.2" → 60.8" (+0.60")

Rate +0.0043" / y

PA drift 191° → 192° (+1°, +0.007°/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.