J/ApJ/463/26 VI photometry of 29 Cepheids in M101. (Kelson+ 1996)
The Extragalactic Distance Scale Key Project. III.
The discovery of Cepheids and a new distance to M101 using the
Hubble Space Telescope.
Kelson D.D., Illingworth G.D., Freedman W.F., Graham J.A., Hill R.,
Madore B.F., Saha A., Stetson P.B., Kennicutt Jr.R.C., Mould J.R.,
Hughes S.M., Ferrarese L., Phelps R., Turner A., Cook K.H., Ford H.,
Hoessel J.G., Huchra J.
<Astrophys. J. 463, 26 (1996)>
=1996ApJ...463...26K 1996ApJ...463...26K
ADC_Keywords: Stars, variable ; Photometry
Mission_Name: HST
Keywords: Cepheids - distance scale - galaxies: distances and redshifts -
galaxies: individual (M101)
Abstract:
We report on the discovery of 29 Cepheid variables in the galaxy M101
using the original Wide Field Camera (WFC) and the new Wide Field and
Planetary Camera 2 (WFPC2) on the Hubble Space Telescope. We observed
a field in M101 at 17 independent epochs in V (F555W), five epochs in
I (F785LP/F814W), and one epoch in B (F439W), with a time interval
baseline of 381 days. We have found Cepheids with periods ranging
from 10 to 60 days. The data have been calibrated using WFPC2
observations with zero points derived from Omega Cen, Pal 4, and NGC
2419 observations. This calibration has been verified by using the
Medium Deep Survey (MDS) WFC photometric zero points, and ground-based
secondary standards in V and I. The V calibrations agree to ±0.06mag,
and the I calibrations agree to ±0.4mag. We have constructed V and I
period-luminosity (PL) relations and have derived apparent distance
moduli based on a distance modulus for the Large Magellanic Cloud
(LMC) of 18.50mag and a reddening of E(B-V)=0.10mag to the LMC
Cepheids. Period-residual minimization was used to minimize the
effects of Malmquist bias on the period-luminosity relation fitting
process. Using a Galactic extinction law and the apparent V and I
distance moduli, we have found a mean reddening for the M101 sample of
E(B-V)=0.03mag and a true distance modulus to M101 of 29.34±0.17mag,
corresponding to a distance of 7.4±0.6Mpc. The sources of error have
been rigorously tracked through an error budget; systematic and random
errors contribute roughly equally to the quoted error. The mean
gas-phase metal abundances in the LMC and in the M101 outer field are
similar so we expect metallicity effects to be minimal. These Cepheids
will be used in conjunction with results from a Key Project search for
Cepheids in an inner field, where the metallicity is larger by a
factor of 5, to probe the effects of abundance on the Cepheid
period-luminosity relation.
Objects:
----------------------------------------------------------
RA (2000) DE Designation(s)
----------------------------------------------------------
14 03 13 +54 20.9 M101 = APG 26
----------------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 22 29 Cepheids observed (mean coordinates)
tableb1.dat 47 660 V photometry
tableb2.dat 47 159 I photometry
--------------------------------------------------------------------------------
See also:
J/ApJ/507/655 : VI photometry of new Cepheids in NGC 2541 (Ferrarese+, 1998)
J/ApJ/508/491 : M101 Cepheids (Stetson+, 1998)
J/ApJ/523/540 : VI photometry of new Cepheids in NGC 3319 (Sakai+, 1999)
J/ApJ/521/155 : New Cepheids and distance to NGC 4535 (Macri+, 1999)
J/ApJ/523/540 : VI photometry of new Cepheids in NGC 3319 (Sakai+, 1999)
J/ApJ/529/723 : VI photometry of Cepheids (Gibson+, 2000)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Cep Cepheid number
4- 8 F5.2 d Per Period, in days.
10 I1 --- CCD Chip number
12- 16 F5.1 pix Xpos Position of Cepheid along X axis
18- 22 F5.1 pix Ypos Position of Cepheid along Y axis
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tableb1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Cep Cepheid number
4- 7 F4.1 d Per Period
9- 21 F13.4 d JD Julian date, midpoint of individual exposure
22 I1 --- CCD Which CCD the star can be found in
24- 29 F6.2 pix Xpos X position on CCD frame
31- 36 F6.2 pix Ypos Y position on CCD frame
38- 42 F5.2 mag Vmag Calibrated F555W magnitude
44- 47 F4.2 mag e_Vmag ALLFRAME uncertainty in F555W magnitude
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tableb2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Cep Cepheid number
4- 7 F4.1 d Per Period
9- 21 F13.4 d JD Julian date, midpoint of individual exposure
22 I1 --- CCD Which CCD the star can be found in
24- 29 F6.2 pix Xpos X position on CCD frame
31- 36 F6.2 pix Ypos Y position on CCD frame
38- 42 F5.2 mag Imag Calibrated F814W magnitude
44- 47 F4.2 mag e_Imag ALLFRAME uncertainty in F814W magnitude
--------------------------------------------------------------------------------
Origin: AAS CD-ROM series, Volume 7, 1996 Lee Brotzman [ADS] 10-Oct-96
(table2 from the printed ApJ edition)
References:
Freedman et al., Paper I 1994ApJ...427..628F 1994ApJ...427..628F
Hughes et al., Paper II 1994ApJ...428..143H 1994ApJ...428..143H
Kelson et al., Paper III 1996ApJ...463...26K 1996ApJ...463...26K, Cat. J/ApJ/463/26
Ferrarese et al., Paper IV 1996ApJ...464..568F 1996ApJ...464..568F
Hill et al., Paper V 1998ApJ...496..648H 1998ApJ...496..648H
Silbermann et al., Paper VI 1996ApJ...470....1S 1996ApJ...470....1S
Graham et al., Paper VII 1997ApJ...477..535G 1997ApJ...477..535G
Rawson et al., Paper VIII 1997ApJ...490..517R 1997ApJ...490..517R
Phelps et al., Paper IX 1998ApJ...500..763P 1998ApJ...500..763P
Hughes et al., Paper X 1998ApJ...501...32H 1998ApJ...501...32H
Turner et al., Paper XI 1998ApJ...505..207T 1998ApJ...505..207T
Ferrarese et al., Paper XII 1998ApJ...507..655F 1998ApJ...507..655F, Cat. J/ApJ/507/655
Kennicutt et al., Paper XIII 1998ApJ...498..181K 1998ApJ...498..181K
Silbermann et al., Paper XIV 1999ApJ...515....1S 1999ApJ...515....1S
Madore et al., Paper XV 1999ApJ...515...29M 1999ApJ...515...29M
Stetson et al., Paper XVI 1998ApJ...508..491S 1998ApJ...508..491S
Gibson et al., Paper XVII 1999ApJ...512...48G 1999ApJ...512...48G
Macri et al., Paper XVIII 1999ApJ...521..155M 1999ApJ...521..155M, Cat. J/ApJ/521/155
Kelson et al., Paper XIX 1999ApJ...514..614K 1999ApJ...514..614K
Graham et al., Paper XX 1999ApJ...516..626G 1999ApJ...516..626G
Mould et al., Paper XXI 2000ApJ...528..655M 2000ApJ...528..655M
Prosser et al., Paper XXII 1999ApJ...525...80P 1999ApJ...525...80P
Sakai et al., Paper XXIII 1999ApJ...523..540S 1999ApJ...523..540S, Cat. J/ApJ/523/540
Sakai et al. Paper XXIV 2000ApJ...529..698S 2000ApJ...529..698S
Gibson et al., Paper XXV 2000ApJ...529..723G 2000ApJ...529..723G, Cat. J/ApJ/529/723
Ferrarese et al. Paper XXVI 2000ApJ...529..745F 2000ApJ...529..745F
Kelson et al. Paper XXVII 2000ApJ...529..768K 2000ApJ...529..768K
Mould et al. Paper XXVIII 2000ApJ...529..786M 2000ApJ...529..786M
History:
* 31-Jan-1997: Original version, from AAS CD-ROM series
* 30-Apr-2008: addition of table2.
(End) Patricia Bauer, [CDS] 31-Jan-1997