Cassiopeia

Cassiopeia W

Cassiopeia chair

common observer pattern · high confidence

The zig-zag W is circumpolar from Alberta and flips to an M when it passes over the pole. It is the northern autumn counterweight to the Big Dipper.

Central RA: 01^h 01^m 18.8^s
Central Dec: +60° 03′ 42″
Brightest member: V 2.23
Best months from 50°N: September–December evenings
Suggested instrument: naked-eye
Approx. span: 13.3°

Finder context

This wider chart is deliberately schematic: it uses nearby bright-star context and boxes the asterism’s member-star footprint, but it does not draw official constellation boundaries or promise horizon/season precision.

Framing: Approximate member-star span: 13.3°; use at least 18.6° field for context.

Observing and imaging

Naked eye

Primary naked-eye pattern; suburban skies should show the main stars unless the description notes a low horizon or dark-sky need.

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 as a wide-field scene in/near Cassiopeia; a field of view around 19° keeps context without claiming exact constellation boundaries.

Tonight from your latitude

Observability from your latitude: uses this asterism’s centroid RA/Dec with a schematic local clock from longitude, astronomical twilight (Sun below −18°), and the 2026 Moon heuristic. Month stays for the seasonal readout.

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

Naked-eye visibility by sky class

Approximate limiting magnitudes: Bortle 3 ≈ V 6.6, Bortle 5 ≈ V 5.6, Bortle 7 ≈ V 4.6. The shape is counted recognisable when at least 70% of defining stars clear the limit.

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

Moon impact

Reference year 2026, Nov: 24/30 nights (80%) have a sampled ≥2 h window with Cassiopeia W above 20° and the Moon below the horizon. At transit the Moon is up on about 50% of nights; the average moonlight penalty is roughly 0.63 mag of naked-eye limiting magnitude. Good nights below are the deterministic 2026 best-month mini-calendar for 50°N; green means a ≥2 h sampled dark window with the Moon down.

010203040506070809101112131415161718192021222324252627282930

Member stars

Name	Bayer / Flamsteed	HR	RA J2000	Dec J2000	V mag
Schedar	18Alp Cas	HR 168	00^h 40^m 30.5^s	+56° 32′ 14″	2.23
Caph	11Bet Cas	HR 21	00^h 09^m 10.7^s	+59° 08′ 59″	2.27
Gamma Cassiopeiae	27Gam Cas	HR 264	00^h 56^m 42.5^s	+60° 43′ 00″	2.47
Ruchbah	37Del Cas	HR 403	01^h 25^m 49.0^s	+60° 14′ 07″	2.68
Segin	45Eps Cas	HR 542	01^h 54^m 23.7^s	+63° 40′ 12″	3.38

Source and confidence

common observer pattern; high confidence. Commonly used constellation-part or seasonal guide-pattern name, with member-star positions plotted from BSC5.

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.