Pegasus / Andromeda

Great Square of Pegasus

Square of Pegasus

common observer pattern · high confidence

Four second-magnitude corner stars make autumn's large empty-looking square. The northeast corner, Alpheratz, now belongs to Andromeda even though the pattern is still the Great Square.

Central RA: 23^h 37^m 32.4^s
Central Dec: +21° 53′ 26″
Brightest member: V 2.06
Best months from 50°N: September–December evenings
Suggested instrument: naked-eye
Approx. span: 20.6°

Finder context

Use the nearby bright stars to locate the gold box, then move to the larger chart for the pattern itself.

Framing: Approximate member-star span: 20.6°; use at least 28.9° field for context.

Observing and imaging

Naked eye

Start with the unaided eye. Suburban skies usually show the main stars.

Binoculars

Binoculars are optional: use them to check colours, nearby doubles, or richer Milky Way background.

Small scope

A telescope is usually too narrow for the whole shape; use it after the pattern has guided you to a target.

Imaging

Frame a 29° field around Pegasus / Andromeda to include the pattern and its nearby stars.

Tonight from your latitude

Set your location and date to see a useful window, peak altitude, sky visibility, and Moon conditions. Use Month to compare the season ahead.

Latitude 50°NLongitude -114°Date Month Sky darkness Bortle 4 · limit V 6.1

Naked-eye visibility by sky class

Bortle class rates night-sky brightness. The atlas counts a pattern as recognisable when at least 70% of its defining stars are visible.

Bortle 3: 4/4 stars — fully visibleBortle 5: 4/4 stars — fully visibleBortle 7: 4/4 stars — fully visible

Moon impact

For 50°N in the best month, green dates mark at least two hours with the pattern above 20° and the Moon below the horizon.

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Member stars

Name	Bayer / Flamsteed	HR	RA J2000	Dec J2000	V mag
Alpheratz	21Alp And	HR 15	00^h 08^m 23.3^s	+29° 05′ 26″	2.06
53Bet Peg	53Bet Peg	HR 8775	23^h 03^m 46.5^s	+28° 04′ 58″	2.42
54Alp Peg	54Alp Peg	HR 8781	23^h 04^m 45.7^s	+15° 12′ 19″	2.49
Algenib	88Gam Peg	HR 39	00^h 13^m 14.2^s	+15° 11′ 01″	2.83

Source and confidence

common observer pattern; high confidence. A commonly used constellation-part or seasonal guide pattern.

Citations

Bright Star Catalogue, 5th Revised Ed.: Hoffleit, D. & Warren, W.H. Jr. (1991). Positions, V magnitudes, Bayer/Flamsteed identifiers. source
Star Tales: Ridpath, I. Constellation and asterism notes used to cross-check common sky-pattern names. source
The Hipparcos and Tycho Catalogues: ESA SP-1200 (1997). Used as the modern astrometric reference named by the atlas; the MVP pages expose BSC5 J2000 fields for the plotted bright-star members.