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

Southworth, J.; Hinse, T. C.; Joergensen, U. G.; Dominik, M.; Ricci, Davide; Burgdorf, M.; Hornstrup, A.; Wheatley, P. J.; Anguita, T.; Bozza, V.; Novati, S. Calchi; Harpsøe, K.; Kjærgaard, P.; Liebig, C.; Mancini, L.; Masi, G.; Mathiasen, M.; Rahvar, S.; Scarpetta, G.; Snodgrass, C.; Surdej, Jean; Thöne, C. C.; Zub, M.

doi:10.1111/j.1365-2966.2009.14767.x

Cited by 212 publications

(187 citation statements)

References 55 publications

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“…The shape and width of the light distribution of the PSF do not really matter. Our method can also be successfully used for images performed in the defocused mode (Southworth et al 2009(Southworth et al , 2014.…”

Section: A Very Efficient Photometric Methodsmentioning

confidence: 99%

Adaptive PSF fitting – a highly performing photometric method and light curves of the GLS H1413+117: time delays and micro-lensing effects

Akhunov

Wertz

Elyiv

et al. 2016

Mon. Not. R. Astron. Soc.

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We present new photometric observations of H1413+117 acquired during seasons between 2001 and 2008 in order to estimate the time delays between the lensed quasar images and to characterize at best the on-going micro-lensing events. We propose a highly performing photometric method called the adaptive point spread function fitting and have successfully tested this method on a large number of simulated frames. This has enabled us to estimate the photometric error bars affecting our observational results. We analysed the V-and R-band light curves and V-R colour variations of the A-D components which show short-and long-term brightness variations correlated with colour variations. Using the χ 2 and dispersion methods, we estimated the time delays on the basis of the R-band light curves over the seasons between 2003 and 2006. We have derived the new values: t AB = −17.4 ± 2.1, t AC = −18.9 ± 2.8 and t AD = 28.8 ± 0.7 d using the χ 2 method (B and C are leading, D is trailing) with 1σ confidence intervals. We also used available observational constraints (resp. the lensed image positions, the flux ratios in mid-IR and two sets of time delays derived in the present work) to update the lens redshift estimation. We obtained z l = 1.95 +0.06 −0.10 which is in good agreement with previous estimations. We propose to characterize two kinds of micro-lensing events: micro-lensing for the A,

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Section: A Very Efficient Photometric Methodsmentioning

confidence: 99%

Adaptive PSF fitting – a highly performing photometric method and light curves of the GLS H1413+117: time delays and micro-lensing effects

Akhunov

Wertz

Elyiv

et al. 2016

Mon. Not. R. Astron. Soc.

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“…All the observations presented in this work were performed using the telescope-defocusing technique (Alonso et al 2008;Southworth et al 2009). In this method, the telescope is defocused so point spread functions (PSFs) cover of the order of 1000 pixels, and long exposure times (up to ∼120 s) are used to collect many photons in each PSF.…”

Section: Telescope Defocussing Observations Of Planetary Transitsmentioning

confidence: 99%

“…All observations were analysed with the DEFOT pipeline (Southworth et al 2009) written in IDL. 3 Debiasing and flat-fielding were done using master calibration frames obtained by mediancombining individual calibration images.…”

Section: O B S E Rvat I O N S a N D Data R E D U C T I O Nmentioning

confidence: 99%

Erratum: Physical properties, star-spot activity, orbital obliquity and transmission spectrum of the Qatar-2 planetary system from multicolour photometry

Mancini

Southworth

Ciceri

et al. 2016

Mon. Not. R. Astron. Soc.

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We present 17 high-precision light curves of five transits of the planet Qatar-2 b, obtained from four defocused 2 m-class telescopes. Three of the transits were observed simultaneously in the Sloan g r i z passbands using the seven-beam Gamma Ray Burst Optical and Near-Infrared Detector imager on the MPG/ESO 2.2-m telescope. A fourth was observed simultaneously in Gunn grz using the Centro Astronómico Hispano Alemán 2.2-m telescope with Bonn University Simultaneous Camera, and in r using the Cassini 1.52-m telescope. Every light curve shows small anomalies due to the passage of the planetary shadow over a cool spot on the surface of the host star. We fit the light curves with the PRISM+GEMC model to obtain the photometric parameters of the system and the position, size and contrast of each spot. We use these photometric parameters and published spectroscopic measurements to obtain the physical properties of the system to high precision, finding a larger radius and lower density for both star and planet than previously thought. By tracking the change in position of one star-spot between two transit observations, we measure the orbital obliquity of Qatar-2 b to be λ = 4.• 3 ± 4.• 5, strongly indicating an alignment of the stellar spin with the orbit of the planet. We calculate the rotation period and velocity of the cool host star to be 11.5 ± 0.2 d and 3.28 ± 0.04 km s −1 at a colatitude of 74 • . We assemble the planet's transmission spectrum over the 386-976 nm wavelength range and search for variations of the measured radius of Qatar-2 b as a function of wavelength. Our analysis highlights a possible H 2 /He Rayleigh scattering in the blue.

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“…We created master bias and flat-field images by mediancombining sets of bias images and sky flats, and used them to correct the science images. Aperture photometry was performed using the idl/astrolib implementation of daophot (Southworth et al 2009). The apertures on the target star were placed by eye, and their sizes were set to a wide range of values to find those that gave photometry with the lowest scatter compared to a fitted model.…”

Section: Cassini Telescopementioning

confidence: 99%

Multi-site campaign for transit timing variations of WASP-12 b: possible detection of a long-period signal of planetary origin

Maciejewski

Dimitrov

Seeliger³

et al. 2013

A&A

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Aims. The transiting planet WASP-12 b was identified as a potential target for transit-timing studies because a departure from a linear ephemeris has been reported in the literature. Such deviations could be caused by an additional planet in the system. We attempt to confirm the claimed variations in transit timing and interpret their origin. Methods. We organised a multi-site campaign to observe transits by WASP-12 b in three observing seasons, using 0.5-2.6-metre telescopes. Results. We obtained 61 transit light curves, many of them with sub-millimagnitude precision. The simultaneous analysis of the best-quality datasets allowed us to obtain refined system parameters, which agree with values reported in previous studies. The residuals versus a linear ephemeris reveal a possible periodic signal that may be approximated by a sinusoid with an amplitude of 0.00068 ± 0.00013 d and period of 500 ± 20 orbital periods of WASP-12 b. The joint analysis of timing data and published radial velocity measurements results in a two-planet model that explains observations better than do single-planet scenarios. We hypothesise that WASP-12 b might not be the only planet in the system, and there might be the additional 0.1 M Jup body on a 3.6-d eccentric orbit. A dynamical analysis indicates that the proposed two-planet system is stable on long timescales.

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

Cited by 212 publications

References 55 publications

Adaptive PSF fitting – a highly performing photometric method and light curves of the GLS H1413+117: time delays and micro-lensing effects

Adaptive PSF fitting – a highly performing photometric method and light curves of the GLS H1413+117: time delays and micro-lensing effects

Erratum: Physical properties, star-spot activity, orbital obliquity and transmission spectrum of the Qatar-2 planetary system from multicolour photometry

Multi-site campaign for transit timing variations of WASP-12 b: possible detection of a long-period signal of planetary origin

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