tau Orionis

data from The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version) (Hoffleit+, 1991)

position, motion, parallax:

position (J2000)	RA: 5h 17min 36.4sec	DEC: -6° 50' 40''
position (B1900)	RA: 5h 12min 45sec	DEC: -6° 57' 9''
proper motion (J2000)	RA: -0.015 arcsec/a	DEC: -0.008 arcsec/a
radial velocity	20 km/s note: spectroscopic binaries
rotational velocity	46 km/s (uncertain) (variable)
trigonometric parallax	0.006 arcsec
galactic coordinates	longitude: 208.28°	latitude: -23.96°

magnitude

visual magnitude

3.6
(V on UBV Johnson system)

spectral / color information

double/multiple star system information

number of components of multiple star system	4
separation	36 arcsec
mag difference (of double or brightest multiple)	7.2
component ID	AD

data from SKY2000 - Master Star Catalog (Myers+ 1997)

position, motion, parallax:

magnitude:

spectral information:

double/multiple star system information:

source of data: 19

separation between brightest and second brightest component	34.8 arcsec
magnitude difference between brightest and second brightest component	7.37
position angle	250 °

sources:

2	HD and HDE Catalogs
Cannon, A.J., and E.C. Pickering, Harvard Annals, Vols 91-99, 1918-24, Cambridge, Massachusetts: Harvard University; Cannon, A.J., Harvard Annals, Vol. 100, 1925-36, Cambridge, Massachusetts: Harvard University; and Cannon, A.J., and M. Walton Mayall, Harvard Annals, Vol. 112, 1949, Cambridge, Massachusetts: Harvard University
15	FK5, FK5 Extension and FK5 Supplement
Fricke, W., H. Schwan and T. Lederle, "Fifth Fundamental Catalogue (FK5), Part I. The Basic Fundamental Stars," Veroff. Astronomisches Recheninstitut, No. 32, Heidelberg, Germany, 1988, and Fricke, W., H. Schwan, and T.E. Corbin, "Fifth Fundamental Catalogue (FK5), Part II. The FK5 Extension," Veröff. Astronomisches Recheninstitut, No. 33, Heidelberg, Germany, 1991
19	WDS Catalog
Worley, C.E., and G.G. Douglass, Washington Catalog of Visual Double Stars 1996.0, United States Naval Observatory, 1996
25	Bright Star Catalogue, 5th edition
Hoffleit, D. and Warren, W.H. Jr., The Bright Star Catalogue, 5th Revised Edition, Version 2, 1994
96	SAO or HD/HDE Catalog
Reference from Value 1 or Reference from Value 2

data from Smithsonian Astrophysical Observatory Star Catalog (SAO Staff 1966; USNO, ADC 1990)

position and proper motion:

position (B1950)	RA: 5h 15min 10.601sec	DEC: -6° 53' 49.05''	±0.005 arcsec
position (J2000)	RA: 5h 17min 36.39sec	DEC: -6° 50' 39.83''
proper motion B1950 (FK4)	RA: -0.0014 arcsec/a	DEC: -0.008 arcsec/a	±0.001 arcsec/a in RA ±0.001 arcsec/a in DEC
proper motion J2000 (FK5)	RA: -0.001 arcsec/a	DEC: -0.008 arcsec/a
source of proper motion data	Determined by source catalog

magnitude:

visual	3.7 (accuracy: 2 decimals)
source of visual magnitude data	Taken from the "Henry Draper Catalogue".

spectral information:

spectral class	B5
source of spectral data	Taken from the Henry Draper Catalogue or no spectrum in source catalog.

catalogues

data from The Washington Visual Double Star Catalog, 1996.0 (Worley+, 1996)

position and proper motion:

position (J2000)	RA: 5h 17.6min	DEC: -6° 51'
proper motion (J2000)	RA: -0.015 arcsec/a	DEC: -0.008 arcsec/a

double/multiple star system information:

discoverer information:

notes:

note	H V 25. Tau Ori.

catalogues and names	t Ori, 20 Ori, HR 1735, HD 34503, SAO 131952, BD -7 1028, FK5: 195, WDS 05176-0651A
constellation	Orion