Boötes / Canes Venatici / Leo / Virgo

Great Diamond

Diamond of Virgo

common observer pattern · high confidence

Arcturus, Cor Caroli, Denebola, and Spica make a huge spring diamond spanning several constellations. It frames the Coma-Virgo galaxy region for binocular and telescope planning.

Central RA: 13^h 06^m 35.3^s
Central Dec: +15° 13′ 40″
Brightest member: V -0.04
Best months from 50°N: March–June evenings
Suggested instrument: naked-eye
Approx. span: 49.9°

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: 49.9°; use at least 69.9° 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

Very large: image as a multi-panel or ultra-wide seasonal sky composition rather than a single telephoto frame.

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

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

Member stars

Name	Bayer / Flamsteed	HR	RA J2000	Dec J2000	V mag
Arcturus	16Alp Boo	HR 5340	14^h 15^m 39.7^s	+19° 10′ 57″	-0.04
Spica	67Alp Vir	HR 5056	13^h 25^m 11.6^s	−11° 09′ 41″	0.98
Denebola	94Bet Leo	HR 4534	11^h 49^m 03.6^s	+14° 34′ 19″	2.14
Cor Caroli	12Alp2CVn	HR 4915	12^h 56^m 01.7^s	+38° 19′ 06″	2.90

Source and confidence

common observer pattern; high confidence. Widely used modern observing guide-pattern; provenance is practical observer usage rather than an official constellation figure.

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.