When is the best time to observe 40 Pegasi?

40 Pegasi is best observed from July through September, with peak visibility during August when it transits around midnight in the Northern Hemisphere.

Where is 40 Pegasi located in the sky?

40 Pegasi lies in the constellation Pegasus at right ascension 22h 39m and declination +19° 31′.

What telescope do I need to split 40 Pegasi?

Splitting 40 Pegasi requires an aperture of roughly 470 mm or larger — the components are separated by about 2.0″ at magnitudes near 5.8. The companion is about 5.6 magnitudes fainter, so glare from the primary — not separation — sets the minimum aperture. Larger apertures and steady seeing help resolve the pair cleanly.

40 Pegasi — Double Star in Pegasus

Magnitude 5.8^m DoubleStar Pegasus (Peg) Visible

Star Map + List + Plan Star Hop

Observe

1Physical Properties

Magnitude 5.82

Spectral Type G8II bright giant

Star Color Orange (B-V 0.92)

Distance 326 ly

2Position & Identifiers

RA 22h 38m 52.6s

Dec +19° 31' 20.0"

Constellation Pegasus (Peg)

HR 8618

HIP 111810

HD 214567

SAO 108064

Flamsteed 40 Peg

SIMBAD

3How easy to split?

Primary 5.8 mag Companion 11.4 mag Separation 2.0″

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.	V. hard	V. hard	V. hard
150 mm Newton 150mm Newt.	V. hard+	V. hard+	V. hard+
Celestron C8 (203 mm SCT) C8 203mm	V. hard+	V. hard+	V. 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 470 mm reflector.

4Visibility

Set a location in User Settings to see visibility data.

Best season Jul – Sep (peak: Aug)

5Multiple Star System

Separation 2.0″

Companion Mag 11.4

Position Angle 239°

Star Colors A: Orange

Discoverer KUI 113

Separation over time

Measured 1935 → 2016 (81 y)

Separation drift 1.9" → 2.0" (+0.10")

Rate +0.0012" / y

PA drift 236° → 239° (+3°, +0.037°/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.