Star Names and Catalogs

Proper Names

About 300 bright stars have traditional proper names, many from Arabic (e.g., Aldebaran, Betelgeuse, Rigel, Vega, Sirius). Some are Greek (Arcturus, Spica) or Latin (Polaris, Bellatrix).

Bayer Designations

Johann Bayer introduced a system in 1603 using Greek letters plus constellation name (e.g., α Orionis = Betelgeuse). Generally, α is brightest, β second brightest, etc., though there are exceptions.

Flamsteed Numbers

John Flamsteed numbered stars within each constellation by right ascension (e.g., 61 Cygni). These are commonly used for stars without Bayer letters.

Star Catalogs

• HD (Henry Draper Catalog) - 225,000+ stars numbered by RA.
• SAO (Smithsonian Astrophysical Observatory) - 250,000+ stars with precise positions.
• HR (Harvard Revised) - Bright star catalog, often cross-referenced with HD.
• Hipparcos - 118,000 stars with extremely precise positions from the Hipparcos satellite.
• Tycho-2 - 2.5 million stars from the Tycho instrument on Hipparcos.

Variable Star Designations

Variable stars use letters R-Z plus constellation (e.g., RR Lyrae, SS Cygni). When these are exhausted, double letters (RR, RS... ZZ) are used, then V plus numbers (V337 Cygni).