When is the best time to observe 4 Pegasi?

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

Where is 4 Pegasi located in the sky?

4 Pegasi lies in the constellation Pegasus at right ascension 21h 39m and declination +05° 46′.

What telescope do I need to split 4 Pegasi?

Splitting 4 Pegasi requires an aperture of roughly 60 mm or larger — the components are separated by about 33.3″ at magnitudes near 5.7. The companion is about 6.1 magnitudes fainter, so glare from the primary — not separation — sets the minimum aperture. Larger apertures and steady seeing help resolve the pair cleanly.

4 Pegasi — Double Star in Pegasus

Magnitude 5.7^m DoubleStar Pegasus (Peg) Visible

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Observe

1Physical Properties

Magnitude 5.67

Spectral Type A9IV-Vn subgiant

Star Color Yellow-white (B-V 0.25)

Distance 99 ly

2Position & Identifiers

RA 21h 38m 31.9s

Dec +05° 46' 18.0"

Constellation Pegasus (Peg)

HR 8270

HIP 106856

HD 205924

SAO 126956

Flamsteed 4 Peg

Double Cat 15157

SIMBAD

3How easy to split?

Primary 5.7 mag Companion 11.8 mag Separation 33.3″

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

Easy Medium Hard Very hard Impossible

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

4Visibility

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Best season Jul – Sep (peak: Aug)

5Multiple Star System

Separation 33.3″

Companion Mag 11.8

Position Angle 310°

Star Colors A: Yellow-white

Discoverer HJ 941

Notes

Optical.

Separation over time

Measured 1827 → 2014 (187 y)

Separation drift 15.0" → 33.3" (+18.30")

Rate +0.0979" / y

PA drift 0° → 310° (-50°, -0.267°/y)

Apparent motion is significant on a human timescale — worth revisiting in a decade.

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.