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The transiting system GJ1214: high-precision defocused transit observations and a search for evidence of transit timing variation

Harpsøe, K. B. W.; Hardis, S.; Hinse, T. C.; Jørgensen, U. G.; Mancini, L.; Southworth, J.; Alsubai, K. A.; Bozza, V.; Browne, P.; Burgdorf, M. J.; Calchi Novati, S.; Dodds, P.; Dominik, M.; Fang, X.-S.; Finet, F.; Gerner, T.; Gu, S.-H.; Hundertmark, M.; Jessen-Hansen, J.; Kains, N.; Kerins, E.; Kjeldsen, H.; Liebig, C.; Lund, M. N.; Lundkvist, M.; Mathiasen, M.; Nesvorný, D.; Nikolov, N.; Penny, M. T.; Proft, S.; Rahvar, S.; Ricci, D.; Sahu, K. C.; Scarpetta, G.; Schäfer, S.; Schönebeck, F.; Snodgrass, C.; Skottfelt, J.; Surdej, J.; Tregloan-Reed, J. and Wertz, O. (2013). The transiting system GJ1214: high-precision defocused transit observations and a search for evidence of transit timing variation. Astronomy & Astrophysics, 549, article no. A10.

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Aims. We present 11 high-precision photometric transitobservations of the transiting super-Earth planet GJ 1214 b. Combining these data with observations from other authors, we investigate the ephemeris for possible signs of transit timing variations (TTVs) using a Bayesian approach.

Methods. The observations were obtained using telescope-defocusing techniques, and achieve a high precision with random errors in the photometry as low as 1 mmag per point. To investigate the possibility of TTVs in the light curve, we calculate the overall probability of a TTV signal using Bayesian methods.

Results. The observations are used to determine the photometric parameters and the physical properties of the GJ 1214 system. Our results are in good agreement with published values. Individual times of mid-transit are measured with uncertainties as low as 10 s, allowing us to reduce the uncertainty in the orbital period by a factor of two.

Conclusions. A Bayesian analysis reveals that it is highly improbable that the observed transit times is explained by TTV caused by a planet in the nominal habitable zone, when compared with the simpler alternative of a linear ephemeris.

Item Type: Journal Item
Copyright Holders: 2012 ESO
ISSN: 1432-0746
Extra Information: 10 pp.
Keywords: planetary systems; statistical methods; observational methods; photometric techniques
Academic Unit/School: Faculty of Science, Technology, Engineering and Mathematics (STEM) > Physical Sciences
Faculty of Science, Technology, Engineering and Mathematics (STEM)
Research Group: Centre for Electronic Imaging (CEI)
Item ID: 43055
Depositing User: Colin Snodgrass
Date Deposited: 28 May 2015 10:32
Last Modified: 07 Dec 2018 10:31
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