Related papers: Simultaneous Estimation of Time Delays and Quasar …
We have measured the time delay between the two images of the gravitationally lensed quasar HE1104-1805 by combining observations made with the Wise Observatory 1m telescope and published observations of this system by Schechter et al.,…
We present three complete seasons and two half-seasons of SDSS r-band photometry of the gravitationally lensed quasar SBS 0909+532 from the U.S. Naval Observatory, as well as two seasons each of SDSS g-band and r-band monitoring from the…
We present a short re-evaluation of a recently published time delay estimate for the gravitational lens system HE 1104-1805 with emphasis on important methodological aspects: bias of the statistics, inconsistency of the methods and use of…
A method for determining the time delays in gravitationally lensed quasars is proposed, which offers a simple and transparent procedure to mitigate the effects of microlensing. The method is based on fundamental properties of representation…
We present 13 seasons of $R$-band photometry of the quadruply-lensed quasar WFI 2033-4723 from the 1.3m SMARTS telescope at CTIO and the 1.2m Euler Swiss Telescope at La Silla, in which we detect microlensing variability of $\sim0.2$ mags…
Microlensing perturbations to the magnification of gravitationally lensed quasar images are dependent on the angular size of the quasar. If quasar variability at visible wavelengths is caused by a change in the area of the accretion disk,…
We test the robustness of published time delays for 11 lensed quasars by using two techniques to measure time shifts in their light curves. We chose to use two fundamentally different techniques to determine time delays in gravitationally…
We present a new method for determining time delays among the light curves of various images in a gravitational lens. The method is based on constructing a simple model for the source variation and forming a chi squared measure of the…
The gravitationally lensed quasar HE 1104-1805 has been observed at a variety of wavelengths ranging from the mid-infrared to X-ray for nearly 20 years. We combine flux ratios from the literature, including recent Chandra data, with new…
We present four new seasons of optical monitoring data and six epochs of X-ray photometry for the doubly-imaged lensed quasar Q J0158-4325. The high-amplitude, short-period microlensing variability for which this system is known has…
We aim to use signatures of microlensing induced by stars in the foreground lens galaxy to infer the size of the accretion disk in the gravitationally lensed quasar Q 0957+561. The long-term photometric monitoring of this system (which so…
We present a measurement of the accretion disk size of the quadruple lensed quasar HE 0435-1223 from well-sampled 13-yr COSMOGRAIL optical light curves. Using accurate time delays for the images A, B, C, and D, we modeled and removed the…
We present optical lightcurves of the gravitationally lensed components A (=A1+A2+A3) and B of the quadruple quasar RX J0911.4+0551 (z = 2.80). The observations were primarily obtained at the Nordic Optical Telescope between 1997 March and…
We present new light curves for the four bright images of the five image cluster-lensed quasar gravitational lens system SDSS~J1004+4112. The light curves span 14.5 yr and allow measurement of the time delay between the trailing bright…
We present Hubble Space Telescope images and 2 years of optical photometry of the quadruple quasar HE0435-1223. The time delays between the intrinsic quasar variations are 14.4+/-0.8 (A-D), 8.0+/-0.8 (A-B) and 2.1+/-0.8 (A-C) days. We also…
We present 426 epochs of optical monitoring data spanning 1000 days from December 2003 to June 2006 for the gravitationally lensed quasar SDSS J1004+4112. The time delay between the A and B images is 38.4+/-2.0 days in the expected sense…
The quadruple quasar H1413+117 (z_s = 2.56) has been monitored with the 2.0 m Liverpool Telescope in the r Sloan band from 2008 February to July. This optical follow-up leads to accurate light curves of the four quasar images (A-D), which…
We present evidence for ultraviolet/optical microlensing in the gravitationally lensed quasar Q0957+561. We combine new measurements from our optical monitoring campaign at the United States Naval Observatory, Flagstaff (USNO) with…
We present eight monitoring seasons of the four brightest images of the gravitational lens SDSS J1004+4112 observed between December 2003 and October 2010. Using measured time delays for the images A, B and C and the model predicted time…
Aims: Our aim is to measure the time delay between the two gravitationally lensed images of the z = 1.547 quasar SDSS J1650+4251, in order to estimate the Hubble constant H_0. Methods: Our measurement is based on R-band light curves with 57…