When is the best time to observe HIP 99585?

HIP 99585 is best observed from June through August, with peak visibility during July when it transits around midnight in the Northern Hemisphere.

Where is HIP 99585 located in the sky?

HIP 99585 lies in the constellation Aquila at right ascension 20h 13m and declination +00° 52′.

What telescope do I need to split HIP 99585?

Splitting HIP 99585 requires an aperture of roughly 100 mm or larger — the components are separated by about 2.6″ at magnitudes near 6.3. Larger apertures and steady seeing help resolve the pair cleanly.

HIP 99585 — Double Star in Aquila

Magnitude 6.3^m DoubleStar Aquila (Aql) Visible

Star Map + List + Plan Star Hop

Observe

1Physical Properties

Magnitude 6.27

Spectral Type B9pCrEu:Sr:

Star Color Blue-white (B-V 0.02)

Distance 362 ly

2Position & Identifiers

RA 20h 12m 35.2s

Dec +00° 52' 03.0"

Constellation Aquila (Aql)

HR 7717

HIP 99585

HD 191984

SAO 125566

Double Cat 13506

SIMBAD

3How easy to split?

Primary 6.3 mag Companion 7.1 mag Separation 2.6″

Sign in and configure your equipment and default location to see a personalized row.

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

Set a location in User Settings to see visibility data.

Best season Jun – Aug (peak: Jul)

5Multiple Star System

Separation 2.6″

Companion Mag 7.1

Position Angle 205°

Star Colors A: Blue-white B: Yellow-white

Discoverer STF2644

Notes

Discordance as to which component has the peculiar spectrum usually attributed to A. However, on the basis of better | spectrograms, Abt gives A = A0V, B = A0Vp(Sr,Cr st.,Ca wk.).

Separation over time

Measured 1783 → 2019 (236 y)

Separation drift 3.0" → 2.6" (-0.40")

Rate -0.0017" / y

PA drift 214° → 205° (-9°, -0.038°/y)

Essentially fixed on human timescales — the same view your grandchildren will see.

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.