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J/ApJ/514/614      VI photometry of new Cepheids in NGC 3198  (Kelson+, 1999)

The Hubble Space Telescope Key Project on the Extragalactic Distance Scale. XIX. The Discovery of Cepheids in and a New Distance to NGC 3198 Kelson D.D., Illingworth G.D., Saha A., Graham J.A., Stetson P.B., Freedman W.L., Kennicutt R.C., Mould J.R., Ferrarese L., Huchra J.P., Madore B.F., Prosser C.F. Bresolin F., Ford H.C., Gibson B. K., Hoessel J.G., Hughes S.M.G., Macri L.M., Sakai S., Silbermann M.A. <Astrophys. J. 514, 614 (1999)> =1999ApJ...514..614K
ADC_Keywords: Stars, variable ; Photometry Mission_Name: HST Keywords: Cepheids - galaxies: distances and redshifts - galaxies: individual (NGC 3198) Abstract: We report the detection of Cepheid variable stars and a new distance to the Sc spiral NGC 3198. NGC 3198 is one of 25 galaxies that have been observed with the WFPC2 of the Hubble Space Telescope (HST) for the purpose of measuring Cepheid distances. Eighteen of these galaxies were targeted by the HST Key Project on the Extragalactic Distance Scale, whose objective is to calibrate a variety of secondary distant indicators and determine the Hubble constant to an accuracy of 10%. NGC 3198 was selected as part of this sample because its type and orientation make it very suitable as a Tully-Fisher calibrator. The WFPC2 data are comprised of 13 epochs in F555W (∼V) and five epochs in F814W (∼I). Two different crowded-field photometry packages (DAOPHOT/ALLFRAME and DoPHOT) were used. The magnitudes derived from these two packages agree to within a few percent. We identified 78 Cepheid candidates in the period range from eight to >50 days, of which 52 were selected for establishing the distance modulus. Period-luminosity relations were constructed in Johnson V and Kron-Cousins I by transforming the F555W and F814W to the standard system. We adopted a distance modulus of µo=18.50±0.10 mag and mean reddening of E(B-V)=0.10 mag to the Large Magellanic Cloud Cepheids and found a true distance modulus to NGC 3198 of µo=30.80±0.16 (random) ±0.12 (systematic) mag. This modulus corresponds to a distance of 14.5 Mpc, with random and systematic errors of ±1.2 and ±0.9 Mpc, respectively. Objects -------------------------------------------- RA (2000) DE Designation(s) -------------------------------------------- 10 19 55 +45 33 09 NGC 3198 = UGC 5572 -------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table5.dat 60 78 Cepheid positions table6.dat 96 78 Cepheid mean magnitudes and periods tablea1.dat 29 2026 Cepheid F555W photometry tablea2.dat 30 810 Cepheid F814W photometry
See also: J/ApJ/463/26 : Extragalactic Distance Scale Key Project. III (Kelson+ 1996) J/ApJ/507/655 : VI photometry of new Cepheids in NGC 2541 (Ferrarese+, 1998) J/ApJ/508/491 : M101 Cepheids (Stetson+, 1998) J/ApJ/521/155 : Extragalactic distance scale key project. XVIII. (Macri+, 1999) J/ApJ/529/723 : VI photometry of Cepheids (Gibson+, 2000) Byte-by-byte Description of file: table5.dat
Bytes Format Units Label Explanations
1- 3 A3 --- CName Cepheid name 10 I1 --- Chip WFPC chip Cepheid is located in (1 is the PC chip) 12- 17 F6.2 --- XPos X position on the chip 19- 24 F6.2 --- YPos Y position on the chip 32- 33 I2 h RAh Right Ascension (J2000) 35- 36 I2 min RAm Right Ascension (J2000) 38- 42 F5.2 s RAs Right Ascension (J2000) 49 A1 --- DE- Declination sign 50- 51 I2 deg DEd Declination (J2000) 53- 54 I2 arcmin DEm Declination (J2000) 56- 60 F5.2 arcsec DEs Declination (J2000)
Byte-by-byte Description of file: table6.dat
Bytes Format Units Label Explanations
1- 3 A3 --- CName Cepheid name 8 A1 --- Use [YN] indicates if the Cepheid was used in the Period-Luminosity analysis 12 A1 --- l_Period limit on Period 13- 17 F5.2 d Period Cepheid period 20- 23 F4.1 d E_Period ? Uncertainty in Period. If e_Period exists this value is the upper limit 25- 28 F4.1 d e_Period ? Lower limit in Period 31- 35 F5.2 mag I.Vmag Intensity weighted mean V band magnitude 39- 42 F4.2 mag e_I.Vmag Uncertainty in I.Vmag 49- 53 F5.2 mag I.Imag ? Intensity weighted mean I band magnitude 57- 60 F4.2 mag e_I.Imag ? Uncertainty in I.Imag 67- 71 F5.2 mag P.Vmag Phase weighted mean V band magnitude 75- 78 F4.2 mag e_P.Vmag Uncertainty in P.Vmag 85- 89 F5.2 mag P.Imag ? Phase weighted mean I band magnitude 93- 96 F4.2 mag e_P.Imag ? Uncertainty in P.Imag
Byte-by-byte Description of file: tablea1.dat
Bytes Format Units Label Explanations
1- 3 A3 --- CName Cepheid name 6- 13 F8.2 --- JD-2400000 Julian date (-2400000) of observation 16- 20 F5.2 mag Vmag V Band magnitude 24- 27 F4.2 mag e_Vmag Uncertainty in Vmag
Byte-by-byte Description of file: tablea2.dat
Bytes Format Units Label Explanations
1- 3 A3 --- CName Cepheid name 6- 13 F8.2 --- JD-2400000 Julian date (-2400000) of observation 16- 20 F5.2 mag Imag I Band magnitude 24- 27 F4.2 mag e_Imag Uncertainty in Vmag
History: From ApJ electronic edition References: (Paper I) Freedman+ 1994ApJ...427..628F (Paper II) Hughes+ 1994ApJ...428..143H (Paper III) Kelson+ 1996ApJ...463...26K, Cat. J/ApJ/463/26 (Paper IV) Ferrarese+ 1996ApJ...464..568F (Paper VI) Silbermann+ 1996ApJ...470....1S (Paper VII) Graham+ 1997ApJ...477..535G (Paper VIII) Rawson+ 1997ApJ...490..517R (Paper IX) Phelps+ 1998ApJ...500..763P (Paper X) Hughes+ 1998ApJ...501...32H (Paper XI) Turner+ 1998ApJ...505..207T (Paper XII) Ferrarese+ 1998ApJ...507..655F, Cat. J/ApJ/507/655 (Paper XIII) Kennicutt+ 1998ApJ...498..181K (Paper XIV) Silbermann+ 1999ApJ...515....1S (Paper XV) Madore+ 1999ApJ...515...29M (Paper XVI) Stetson+ 1998ApJ...508..491S (Paper XVII) Gibson+ 1999ApJ...512...48G (Paper XVIII) Macri+ 1999ApJ...521..155M, Cat. J/ApJ/521/155 (Paper XX) Graham+ 1999ApJ...516..626G (Paper XXI) Mould+ 2000ApJ...528..655M (Paper XXII) Prosser+ 1999ApJ...525...80P (Paper XXIII) Sakai+ 1999ApJ...523..540S (Paper XXIV) Sakai+ 2000ApJ...529..698S (Paper XXV) Gibson+ 2000ApJ...529..723G, Cat. J/ApJ/529/723 (Paper XXVI) Ferrarese+ 2000ApJ...529..745F (Paper XXVII) Kelson+ 2000ApJ...529..768K (Paper XXVIII) Mould+ 2000ApJ...529..786M
(End) Greg Schwarz (AAS) 16-Feb-2000
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