The object was found in the following catalogues:
  1. The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version)

  2. SKY2000 - Master Star Catalog

  3. Smithsonian Astrophysical Observatory Star Catalog

  4. The Washington Visual Double Star Catalog, 1996.0

  5. Combined General Catalogue of Variable Stars (Vol. I-III)

catalogues and names Alfirk, b Cep, bet Cep, 8 Cep, HR 8238, HD 205021, SAO 10057, FK5: 809, WDS 21287+7034A
other names Alphirk
constellation Cepheus

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

note (category: star names): Alfirk; Alphirk.

position, motion, parallax:

position (J2000) RA: 21h 28min 39,6sec DEC: +70 33' 39''
position (J1900) RA: 21h 27min 22,2sec DEC: +70 7' 18''
proper motion (J2000) RA: 0,01 arcsec/a DEC: 0,007 arcsec/a
radial velocity -8 km/s
note: spectroscopic binaries
note: orbital data avaible
rotational velocity 28 km/s (uncertain) (variable)
trigonometric parallax 0,014 arcsec
note (category: dynamical parallaxes): 0.004".


visual magnitude 3,23
(V on UBV Johnson system)

spectral / color information

spectral class B1IV
B-V-magnitude -0,22
U-B-magnitude -0,95
R-I-magnitude -0,22

variability information

variable star identification Bet Cep
note (category: variability): ADS 15032A, Beta C 3.16 - 3.27V, 0.1904881d, modulation period 10.893d. SiIV and CIV vary. Satellite UV obs. indicate temp. varies 1340d, max./min. radius 1.038.

double/multiple star system information

number of components of multiple star system 3
separation 13,4 arcsec
mag difference (of double or brightest multiple) 4,6
component ID AB
note (category: double and multiple data): ADS 15032AB, 50y. B, 7.84V, +0.18(B-V), +0.06(U-B), A2.5V, vsini 60:k/s. Third component discovered by speckle interferometry, mag. diff about 4v. Sep. 0.025". Possible circumstellar material.
note (category: spectroscopic binaries): ADS 15032A, 10.893d, K 3.1k/s, V0 -3.1k/s, asini 0.397. Resolved by speckle interferometry 1986.45, sep. 0.11".

miscellaneous information

note (category: group membership): Cep OB1.

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

position, motion, parallax:

position (J2000) RA: 21h 28min 39,6sec DEC: +70 33' 38,61'' 0,06 arcsec source: 15
proper motion (J2000) RA: 0,0021 arcsec/a DEC: 0,007 arcsec/a source: 25
radial velocity -8 km/s source: 25
trigonometric parallax 0,014 0,001 arcsec source: 25
galactic coord. (B1950) longitude: 107,54 latitude: 14,03
GCI unit vector (J2000) X: 0,262845 Y: -0,204141 Z: 0,942995


visual 3,2 (observed) source: 31
photovisual 3,3 source: 2

spectral information:

spectral class B1 source: 96
Morgan-Keenan B1IV source: 25
B-magnitude 3,01 0,05 B-V-magnitude -0,22
U-magnitude 2,06 0,05 U-B-magnitude -0,95

variability information:

source of data: 30
variability type 140
var. amplitude 0,11
var. period 0,19
var. epoch 2440445
11. August 1969, 12:00:00 UT
next max light 2451620,42
16. March 2000, 22:04:48 UT

double/multiple star system information:

source of data: 19
separation between brightest and second brightest component 0,1 arcsec
position angle 51


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
30 GCVS, 4th edition
Kholopov, P.N., et al., General Catalogue of Variable Stars, fourth edition, Moscow: Nauka Publishing House, 1985-88
31 CRM' (non-GCVS variable data)
Warren, W.H. Jr., Northern Hemisphere Catalog of Red Magnitudes, 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 (J1950) RA: 21h 28min 1,326sec DEC: +70 20' 27,85'' 0,003 arcsec
position (J2000) RA: 21h 28min 39,628sec DEC: +70 33' 38,67''
proper motion J1950 (FK4) RA: 0,002 arcsec/a DEC: 0,013 arcsec/a 0,001 arcsec/a in RA
0,001 arcsec/a in DEC
proper motion J2000 (FK5) RA: 0,0024 arcsec/a DEC: 0,008 arcsec/a
source of proper motion data Determined by source catalog


visual 3,3 (accuracy: 2 decimals)
source of visual magnitude data Taken from the "Henry Draper Catalogue".

spectral information:

spectral class B1
source of spectral data Taken from the Henry Draper Catalogue or no spectrum in source catalog.


source catalogue FK4, catalogue number: 809
Durchmusterung BD+69 1173
Boss General Catalogue 30118
Henry Draper Catalogue 205021

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

position and proper motion:

position (J2000) RA: 21h 28,7min DEC: +70 34'
proper motion (J2000) RA: 0,01 arcsec/a DEC: 0,007 arcsec/a

double/multiple star system information:

component year number of measures position angle angular separation magnitude of 1st component magnitude of 2nd component spectral class(es) discoverer code
Aa 1971 30 48 0,3'' 3,2 - B2III LAB
1990 51 0,1''
Aa-B 1832 59 251 13,4'' 3,2 7,8 - STF2806
1975 249 -

discoverer information:

discoverer code discoverer reference
LAB Labeyrie et al
STF2806 Struve, F.G.W. -


note Beta Cep. The third component was discovered recently by speckle interferometry.

data from Combined General Catalogue of Variable Stars (Vol. I-III) (Kholopov+ 1998)


position (J1950) RA: 21h 28min 1,3sec DEC: +70 20' 28''

variability informations:

variability type BCEP pulsating variable star
magnitute at max. brightness 3,16
magnitute at min. brightness 3,27
photometric system visual, photovisual or Johnson's V
epoch for maximum light [JD] 2440444,625
11. August 1969, 03:00:00 UT
period [d] 0,1904881
next maximum light [JD] 2451620,3713389
16. March 2000, 20:54:44 UT
rising time 50 % of period

spectral information

spectral class B2IIIeV


to a study Vol. I GCVS (see Kholopov et al. 1985-1988)
to a chart/photograph no chart is avaible, but the star is contained in the 'Bonner Durchmusterung'


ID in the GCVS catalogue 20/9002
constellation Cepheus
notes on existence The star is equivalent to '0209004 del'.
There are notes in published catalog.

variability type description

variability type description
BCEP Variables of the Beta Cephei type (Beta Cep, Beta CMa), which are pulsating O8-B6 I-V stars with periods of light and radial-velocity variations in the range of 0.1 - 0.6 days and light amplitudes from 0.01 to 0.3 mag in V. The light curves are similar in shape to average radial-velocity curves but lag in phase by a quarter of the period, so that maximum brightness corresponds to
maximum contraction, i.e., to minimum stellar radius. The majority of these stars probably show radial pulsations, but some (V649 Per) display nonradial pulsations; multiperiodicity is characteristic of many of these stars.