## High-precision photometry by telescope defocusing - I. The transiting planetary system WASP-5

Publication: Research - peer-review › Journal article – Annual report year: 2009

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**High-precision photometry by telescope defocusing - I. The transiting planetary system WASP-5.** / Southworth, J.; Hinse, T. C.; Jørgensen, U. G.; Dominik, M.; Ricci, D.; Burgdorf, M. J.; Hornstrup, Allan; Wheatley, P. J.; Anguita, T.; Bozza, V.; Novati, S. C.; Harpsoe, K.; Kjærgaard, P.; Liebig, C.; Mancini, L.; Masi, G.; Mathiasen, M.; Rahvar, S.; Scarpetta, G.; Snodgrass, C.; Surdej, J.; Thone, C. C.; Zub, M.

Publication: Research - peer-review › Journal article – Annual report year: 2009

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*Royal Astronomical Society. Monthly Notices*, vol 396, no. 2, pp. 1023-1031., 10.1111/j.1365-2966.2009.14767.x

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*Royal Astronomical Society. Monthly Notices*,

*396*(2), 1023-1031. 10.1111/j.1365-2966.2009.14767.x

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*Royal Astronomical Society. Monthly Notices*. 2009, 396(2). 1023-1031. Available: 10.1111/j.1365-2966.2009.14767.x

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TY - JOUR

T1 - High-precision photometry by telescope defocusing - I. The transiting planetary system WASP-5

A1 - Southworth,J.

A1 - Hinse,T. C.

A1 - Jørgensen,U. G.

A1 - Dominik,M.

A1 - Ricci,D.

A1 - Burgdorf,M. J.

A1 - Hornstrup,Allan

A1 - Wheatley,P. J.

A1 - Anguita,T.

A1 - Bozza,V.

A1 - Novati,S. C.

A1 - Harpsoe,K.

A1 - Kjærgaard,P.

A1 - Liebig,C.

A1 - Mancini,L.

A1 - Masi,G.

A1 - Mathiasen,M.

A1 - Rahvar,S.

A1 - Scarpetta,G.

A1 - Snodgrass,C.

A1 - Surdej,J.

A1 - Thone,C. C.

A1 - Zub,M.

AU - Southworth,J.

AU - Hinse,T. C.

AU - Jørgensen,U. G.

AU - Dominik,M.

AU - Ricci,D.

AU - Burgdorf,M. J.

AU - Hornstrup,Allan

AU - Wheatley,P. J.

AU - Anguita,T.

AU - Bozza,V.

AU - Novati,S. C.

AU - Harpsoe,K.

AU - Kjærgaard,P.

AU - Liebig,C.

AU - Mancini,L.

AU - Masi,G.

AU - Mathiasen,M.

AU - Rahvar,S.

AU - Scarpetta,G.

AU - Snodgrass,C.

AU - Surdej,J.

AU - Thone,C. C.

AU - Zub,M.

PB - Wiley-Blackwell Publishing Ltd.

PY - 2009

Y1 - 2009

N2 - We present high-precision photometry of two transit events of the extrasolar planetary system WASP-5, obtained with the Danish 1.54-m telescope at European Southern Obseratory La Silla. In order to minimize both random and flat-fielding errors, we defocused the telescope so its point spread function approximated an annulus of diameter 40 pixel (16 arcsec). Data reduction was undertaken using standard aperture photometry plus an algorithm for optimally combining the ensemble of comparison stars. The resulting light curves have point-to-point scatters of 0.50 mmag for the first transit and 0.59 mmag for the second. We construct detailed signal-to-noise ratio calculations for defocused photometry, and apply them to our observations. We model the light curves with the JKTEBOP code and combine the results with tabulated predictions from theoretical stellar evolutionary models to derive the physical properties of the WASP-5 system. We find that the planet has a mass of M-b = 1.637 +/- 0.075 +/- 0.033 M-Jup, a radius of R-b = 1.171 +/- 0.056 +/- 0.012 R-Jup, a large surface gravity of g(b) = 29.6 +/- 2.8 m s(-2) and a density of rho(b) = 1.02 +/- 0.14 +/- 0.01 rho(Jup) (statistical and systematic uncertainties). The planet's high equilibrium temperature of T-eq = 1732 +/- 80 K makes it a good candidate for detecting secondary eclipses.

AB - We present high-precision photometry of two transit events of the extrasolar planetary system WASP-5, obtained with the Danish 1.54-m telescope at European Southern Obseratory La Silla. In order to minimize both random and flat-fielding errors, we defocused the telescope so its point spread function approximated an annulus of diameter 40 pixel (16 arcsec). Data reduction was undertaken using standard aperture photometry plus an algorithm for optimally combining the ensemble of comparison stars. The resulting light curves have point-to-point scatters of 0.50 mmag for the first transit and 0.59 mmag for the second. We construct detailed signal-to-noise ratio calculations for defocused photometry, and apply them to our observations. We model the light curves with the JKTEBOP code and combine the results with tabulated predictions from theoretical stellar evolutionary models to derive the physical properties of the WASP-5 system. We find that the planet has a mass of M-b = 1.637 +/- 0.075 +/- 0.033 M-Jup, a radius of R-b = 1.171 +/- 0.056 +/- 0.012 R-Jup, a large surface gravity of g(b) = 29.6 +/- 2.8 m s(-2) and a density of rho(b) = 1.02 +/- 0.14 +/- 0.01 rho(Jup) (statistical and systematic uncertainties). The planet's high equilibrium temperature of T-eq = 1732 +/- 80 K makes it a good candidate for detecting secondary eclipses.

KW - techniques: photometric

KW - methods: observational

KW - binaries: eclipsing

KW - stars: individual: WASP-5

KW - methods: data analysis

KW - planetary systems

U2 - 10.1111/j.1365-2966.2009.14767.x

DO - 10.1111/j.1365-2966.2009.14767.x

JO - Royal Astronomical Society. Monthly Notices

JF - Royal Astronomical Society. Monthly Notices

SN - 0035-8711

IS - 2

VL - 396

SP - 1023

EP - 1031

ER -