Perseus

Alpha Persei Cluster

Melotte 20, Mirfak association

catalogue / cluster listing · high confidence

The bright association around Mirfak is a sprawling binocular field rather than a tight cluster. Sweep it after Cassiopeia rises: the stars look like a loose river running through Perseus.

Central RA: 03^h 40^m 06.4^s
Central Dec: +44° 43′ 38″
Brightest member: V 1.79
Best months from 50°N: September–December evenings
Suggested instrument: 7x50
Approx. span: 18.8°

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: 18.8°; use at least 26.3° field for context.

Observing and imaging

Naked eye

Possible as a haze or partial pattern only from darker skies; use naked-eye stars nearby for the hop.

Binoculars

Best treated as a binocular field; start with 7×50 or similar and allow roughly 18.8° of pattern spread.

Small scope

Use low power only; higher magnification breaks the pattern into separate stars.

Imaging

Frame as a wide-field scene in/near Perseus; a field of view around 26° keeps context without claiming exact constellation boundaries.

Observability from your latitude

Uses this asterism’s centroid RA/Dec: transit altitude, hours above 20°, and a month-scale evening window. Default is Edmonton-ish 50°N.

Latitude 50°NMonth 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: 8/8 stars — fully visibleBortle 5: 8/8 stars — fully visibleBortle 7: 7/8 stars — partial

Member stars

Name	Bayer / Flamsteed	HR	RA J2000	Dec J2000	V mag
Mirfak	33Alp Per	HR 1017	03^h 24^m 19.4^s	+49° 51′ 40″	1.79
44Zet Per	44Zet Per	HR 1203	03^h 54^m 07.9^s	+31° 53′ 01″	2.85
45Eps Per	45Eps Per	HR 1220	03^h 57^m 51.2^s	+40° 00′ 37″	2.89
39Del Per	39Del Per	HR 1122	03^h 42^m 55.5^s	+47° 47′ 15″	3.01
41Nu Per	41Nu Per	HR 1135	03^h 45^m 11.6^s	+42° 34′ 43″	3.77
37Psi Per	37Psi Per	HR 1087	03^h 36^m 29.4^s	+48° 11′ 34″	4.23
35Sig Per	35Sig Per	HR 1052	03^h 30^m 34.5^s	+47° 59′ 43″	4.36
34 Per	34 Per	HR 1044	03^h 29^m 22.1^s	+49° 30′ 32″	4.67

Source and confidence

catalogue / cluster listing; high confidence. Cluster or catalogue-associated asterism cross-checked against Sky Catalogue 2000.0 plus BSC5 member-star data.

Citations

Bright Star Catalogue, 5th Revised Ed.: Hoffleit, D. & Warren, W.H. Jr. (1991). Positions, V magnitudes, Bayer/Flamsteed identifiers. source
Sky Catalogue 2000.0: Hirshfeld, A. & Sinnott, R.W. (eds.). Vol. 2: Double Stars, Variable Stars and Nonstellar Objects. Used for cluster/asterism cross-checks.
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.