Cetus

Head of Cetus

Cetus head

skylore / traditional name · medium confidence

Menkar and nearby third- and fourth-magnitude stars form the whale's head below Pisces and Aries. It is best on quiet autumn nights when the eastern sky is relatively dim.

Central RA: 02^h 38^m 20.3^s
Central Dec: +06° 56′ 57″
Brightest member: V 2.53
Best months from 50°N: September–December evenings
Suggested instrument: naked-eye
Approx. span: 13.1°

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: 13.1°; use at least 18.4° 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 Cetus; a field of view around 18° 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, Dec: 21/31 nights (68%) have a sampled ≥2 h window with Head of Cetus above 20° and the Moon below the horizon. At transit the Moon is up on about 42% of nights; the average moonlight penalty is roughly 0.59 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.

01020304050607080910111213141516171819202122232425262728293031

Member stars

Name	Bayer / Flamsteed	HR	RA J2000	Dec J2000	V mag
Menkar	92Alp Cet	HR 911	03^h 02^m 16.8^s	+04° 05′ 23″	2.53
86Gam Cet	86Gam Cet	HR 804	02^h 43^m 18.0^s	+03° 14′ 09″	3.47
87Mu Cet	87Mu Cet	HR 813	02^h 44^m 56.5^s	+10° 06′ 51″	4.27
73Xi 2Cet	73Xi 2Cet	HR 718	02^h 28^m 09.5^s	+08° 27′ 36″	4.28
65Xi 1Cet	65Xi 1Cet	HR 649	02^h 13^m 00.0^s	+08° 50′ 48″	4.37

Source and confidence

skylore / traditional name; medium confidence. Traditional or folk name carried through older public-domain star-name literature; the plotted stars are still BSC5 positions.

Citations

Bright Star Catalogue, 5th Revised Ed.: Hoffleit, D. & Warren, W.H. Jr. (1991). Positions, V magnitudes, Bayer/Flamsteed identifiers. source
Star Names and Their Meanings: Allen, R.H. (1899). Public-domain skylore and traditional names.
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.