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

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 Chi(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: Delta t(AB) = -17.4 +/- 2.1, Delta t(AC) = -18.9 +/- 2.8 and Delta t(AD) = 28.8 +/- 0.7 d using the x(2) method ( B and C are leading, D is trailing) with 1 sigma 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(1) = 1.95(0.10)(+0.06) which is in good agreement with previous estimations. We propose to characterize two kinds of micro-lensing events: micro-lensing for the A, B, C components corresponds to typical variations of similar to 10 (4) mag d 1 during all the seasons, while the D component shows an unusually strong micro-lensing effect with variations of up to similar to 10 (3) mag d (1) during 2004 and 2005.