When is the best time to observe 1 Pegasi?

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

Where is 1 Pegasi located in the sky?

1 Pegasi lies in the constellation Pegasus at right ascension 21h 22m and declination +19° 48′.

What telescope do I need to split 1 Pegasi?

Splitting 1 Pegasi requires an aperture of roughly 60 mm or larger — the components are separated by about 36.6″ at magnitudes near 4.1. The companion is about 5.2 magnitudes fainter, so glare from the primary — not separation — sets the minimum aperture. Larger apertures and steady seeing help resolve the pair cleanly.

1 Pegasi — Double Star in Pegasus

Magnitude 4.1^m DoubleStar Pegasus (Peg) Visible

Star Map + List + Plan

Observe

1Physical Properties

Magnitude 4.08

Spectral Type K1III giant

Star Color Orange (B-V 1.11)

Distance 233 ly

2Position & Identifiers

RA 21h 22m 05.2s

Dec +19° 48' 16.0"

Constellation Pegasus (Peg)

HR 8173

HIP 105502

HD 203504

SAO 107073

Flamsteed 1 Peg

Double Cat 14909

SIMBAD

3How easy to split?

Primary 4.1 mag Companion 9.3 mag Separation 36.6″

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.	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

Set a location in User Settings to see visibility data.

Best season Jul – Sep (peak: Aug)

5Multiple Star System Triple C: optical

Components 3 (triple)

Component IDs AB

Separation 36.6″

Companion Mag 9.3

Companion Sp K0V

Position Angle 313°

Star Colors A: Orange B: Orange

Discoverer STFB 11

Notes

AB CPM. Companion K0V.

Separation over time

Measured 1780 → 2020 (240 y)

Separation drift 37.1" → 36.6" (-0.50")

Rate -0.0021" / y

PA drift 308° → 313° (+5°, +0.021°/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.