catalogues and names

The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version)

SKY2000 - Master Star Catalog

Smithsonian Astrophysical Observatory Star Catalog

The Washington Visual Double Star Catalog, 1996.0

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

catalogues and names

catalogues and names	V1661 Cyg, 55 Cyg, HR 7977, HD 198478, SAO 50099, BD +45 3291, WDS 20489+4607
constellation	Cygnus

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

position, motion, parallax:

position (J2000)	RA: 20h 48min 56.3sec	DEC: +46° 6' 51''
position (2000.72)	RA: 20h 48min 57sec	DEC: +46° 7' 1''
position (B1900)	RA: 20h 45min 31.8sec	DEC: +45° 44' 35''
proper motion (J2000)	RA: 0.004 arcsec/a	DEC: 0 arcsec/a
radial velocity	-7 km/s note: variable radial velocity
rotational velocity	35 km/s (uncertain) (variable)
trigonometric parallax	0.017 arcsec
galactic coordinates	longitude: 85.75°	latitude: 1.49°

note (category: radial and/or rotational velocities):

4-5d inside atmospheric motion 15-16d. RV results confirmed by H alpha profiles.

magnitude

visual magnitude

4.84 (V on UBV Johnson system)

spectral / color information

spectral class	B3Ia
B-V-magnitude	0.41
U-B-magnitude	-0.45
R-I-magnitude

variability information

variable star identification

V1661 Cyg

note (category: variability):

Alpha Cyg 4.81 - 4.87V, no clear periodicity. Small variations in polarization have been observed, 2.0 to 2.6%.

double/multiple star system information

separation	21.3 arcsec
mag difference (of double or brightest multiple)	6.3

note (category: double and multiple data):

Optical.

miscellaneous information

note (category: group membership):

NGC 457. Cyg OB7.

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

position, motion, parallax:

position (J2000)	RA: 20h 48min 56.281sec	DEC: +46° 6' 50.9''	±0.2 arcsec	source: 52
position (2000.72)	RA: 20h 48min 57sec	DEC: +46° 7' 1''	JD: 2451809.25
proper motion (J2000)	RA: -0.0007 arcsec/a	DEC: -0.002 arcsec/a		source: 25
radial velocity	-7 km/s			source: 25
trigonometric parallax	0.017 arcsec		±0.002 arcsec	source: 25
galactic coord. (B1950)	longitude: 85.76°	latitude: 1.49°

magnitude:

visual	4.8 (observed)	source: 31
photovisual	4.9	source: 2
photographic	4.7	source: 16

spectral information:

spectral class	B2		source: 96
Morgan-Keenan	B3Ia		source: 25
B-magnitude	5.25 ±0.05	B-V-magnitude	0.41
U-magnitude	4.8 ±0.05	U-B-magnitude	-0.45

variability information:

source of data: 30

variability type	133
var. amplitude	0.06

double/multiple star system information:

source of data: 19

separation between brightest and second brightest component	21.3 arcsec
magnitude difference between brightest and second brightest component	6.32
position angle	174 °

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
16	PPM North and PPM South Catalogs and PPM Supplement
Roser, S., and U. Bastian, "Catalogue of Positions and Proper Motions," A&AS, Vol. 74, p. 449, 1988, and Bastian, U., et al., "Catalogue of Positions and Proper Motions - South," 1993
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
52	PPMN-HP subset
PPMN Star Catalogue (Reference 16) High-Precision Subset (Code H)
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: 20h 47min 13.981sec	DEC: +45° 55' 40.44''	±0.022 arcsec
position (2000.72)	RA: 20h 48min 58sec	DEC: +46° 7' 1''	JD: 2451809.25
position (J2000)	RA: 20h 48min 56.35sec	DEC: +46° 6' 51.24''
proper motion B1950 (FK4)	RA: 0.0001 arcsec/a	DEC: 0.003 arcsec/a	±0.004 arcsec/a in RA ±0.003 arcsec/a in DEC
proper motion J2000 (FK5)	RA: 0.0004 arcsec/a	DEC: 0 arcsec/a
source of proper motion data	Determined by source catalog

magnitude:

visual	4.9 (accuracy: 2 decimals)
source of visual magnitude data	Taken from Harvard or San Luis photometry.

spectral information:

spectral class	B2
source of spectral data	Taken from the Henry Draper Catalogue or no spectrum in source catalog.

remarks for duplicity and variability

Double star in Aitken's Double Star Catalogue (Aitken 1932)

catalogues

source catalogue	GC, catalogue number: 29036
Durchmusterung	BD+45 3291
Boss General Catalogue	29036
Henry Draper Catalogue	198478

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

position and proper motion:

position (J2000)	RA: 20h 48.9min	DEC: +46° 7'
proper motion (J2000)	RA: -0.002 arcsec/a	DEC: -0.005 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
-	1875	5	174°	20.5''	4.82	11.14	B3Iae	HJ 1581
	1934		-	21.3''

discoverer information:

discoverer code	discoverer	reference
HJ 1581	Herschel, J.	-

notes:

note	55 Cyg. Variable.

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

position:

position (equinox 1950.0)

RA: 20h 47min 14sec

DEC: +45° 55' 40''

variability informations:

variability type	ACYG	pulsating variable star
magnitute at max. brightness	4.81
magnitute at min. brightness	4.87
photometric system	visual, photovisual or Johnson's V

spectral information

spectral class

B3eaIa

references

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'

miscanellous

ID in the GCVS catalogue	31/1661
constellation	Cygnus
notes on existence	The star is equivalent to '0311662 V1662'.
There are notes in published catalog.

variability type description

variability type	description
ACYG	Variables of the Alpha Cygni type, which are nonradially pulsating supergiants of Bep-AepIa spectral types. The light changes with amplitudes of the order of 0.1 mag often seem irregular, being caused by the superposition of many oscillations with close periods. Cycles from several days to several weeks are observed.