TY  - JOUR
A1  - Alcalde, D.
A1  - Mediavilla, E.
A1  - Moreau, O.
A1  - De Rop, Y.
A1  - Barrena, R.
A1  - Gil-Merino, Rodrigo
A1  - McLeod, B. A.
A1  - Motta, V.
A1  - Oscoz, Alejandro
A1  - Serra-Ricart, M.
T1  - QSO 2237+0305 VR light curves from Gravitational Lenses International Time Project optical monitoring
N2  - We present VR observations of QSO 2237+0305 conducted by the Gravitational Lensing International Time Project collaboration from 1999 October 1 to 2000 February 3. The observations were made with the 2.56 m Nordic Optical Telescope at Roque de los Muchachos Observatory, La Palma (Spain). The point-spread function (PSF) fitting method and an adapted version of the ISIS subtraction method have been used to derive the VR light curves of the four components (A-D) of the quasar. The mean errors range in the intervals 0.01-0.04 mag (PSF fitting) and 0.01-0.02 mag (ISIS subtraction), with the faintest component (D) having the largest uncertainties. We address the relatively good agreement between the A and D light curves derived using different filters, photometric techniques, and telescopes. The new VR light curves of component A extend the time coverage of a high-magnification microlensing peak, which was discovered by the OGLE team.
Y1  - 2002
ER  - 
TY  - JOUR
A1  - Goicoechea, Luis Julian
A1  - Alcalde, D.
A1  - Mediavilla, E.
A1  - Munoz, J. A.
A1  - Gil-Merino, Rodrigo
T1  - The nature and size of the optical continuum source in QSO 2237+0305
N2  - From the peak of a gravitational microlensing high-magnification event in the A component of QSO 2237+0305, which was accurately monitored by the Gravitational Lenses International Time Project collaboration, we derived new information on the nature and size of the optical V-band and R-band sources in the distant quasar. If the microlensing peak is caused by a microcaustic crossing, we first obtain that the standard accretion disk is a scenario more reliable/ feasible than other typical axially symmetric models. Moreover, the standard scenario fits both the V-band and R-band observations with reduced ?2 values very close to 1. Taking into account all these results, a standard accretion disk around a supermassive black hole is a good candidate for the optical continuum main source in QSO 2237+0305. Second, using the standard source model and a robust upper limit on the transverse galactic velocity, we infer that 90% of the V- band and R-band luminosities are emitted from a region with a radial size less than 1.2×10-2 pc (=3.7×1016 cm, at a 2 ? confidence level).
Y1  - 2002
ER  -