When is the best time to observe 11 Aquilae?

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

Where is 11 Aquilae located in the sky?

11 Aquilae lies in the constellation Aquila at right ascension 18h 59m and declination +13° 37′.

What telescope do I need to split 11 Aquilae?

Splitting 11 Aquilae requires an aperture of roughly 60 mm or larger — the components are separated by about 20.8″ at magnitudes near 5.2. 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.

11 Aquilae — Double Star in Aquila

Magnitude 5.2^m DoubleStar Aquila (Aql) Visible

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Observe

1Physical Properties

Magnitude 5.23

Spectral Type F8V

Star Color Yellow (B-V 0.53)

Distance 84 ly

2Position & Identifiers

RA 18h 59m 05.7s

Dec +13° 37' 21.0"

Constellation Aquila (Aql)

HR 7172

HIP 93203

HD 176303

SAO 104308

Flamsteed 11 Aql

Double Cat 11902

SIMBAD

3How easy to split?

Primary 5.2 mag Companion 9.3 mag Separation 20.8″

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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 May – Jul (peak: Jun)

5Multiple Star System Triple optical

Components 3 (triple)

Component IDs AB

Separation 20.8″

Companion Mag 9.3

Position Angle 304°

Star Colors A: Yellow B: Red

Discoverer STF2424

Notes

Both companions optical.

Separation over time

Measured 1820 → 2019 (199 y)

Separation drift 20.1" → 20.8" (+0.70")

Rate +0.0035" / y

PA drift 236° → 304° (+68°, +0.342°/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.