@article{CassanBeaulieuBrillantetal.2004,
  author    = {Cassan, A. and Beaulieu, Jean-Philippe and Brillant, Stephane and Coutures, C. and Dominik, M. and Donatowicz, J. and Jorgensen, Uffe Grae and Kubas, Daniel and Albrow, Michael D. and Caldwell, John A. R. and Fouque, P. and Greenhill, John and Hill, K. and Horne, Keith and Kane, Stephen R. and Martin, Ralph and Menzies, J. W. and Pollard, K. R. and Sahu, K. C. and Vinter, C. and Wambsganss, Joachim and Watson, R. and Williams, A. and Fendt, Christian and Hauschildt, P. and Heinmueller, Janine and Marquette, Jean-Baptiste and Thurl, C.},
  title     = {Probing the atmosphere of the bulge G5III star OGLE-2002-BUL-069 by analysis of microlensed H alpha line},
  year      = {2004},
  abstract  = {We discuss high-resolution, time-resolved spectra of the caustic exit of the binary microlensing event OGLE 2002-BLG-069 obtained with UVES on the VLT. The source star is a G5III giant in the Galactic Bulge. During such events, the source star is highly magnified, and a strong differential magnification around the caustic resolves its surface. Using an appropriate model stellar atmosphere generated by the PHOENIX v2.6 code we obtain a model light curve for the caustic exit and compare it with a dense set of photometric observations obtained by the PLANET microlensing follow up network. We further compare predicted variations in the Halpha equivalent width with those measured from our spectra. While the model and observations agree in the gross features, there are discrepancies suggesting shortcomings in the model, particularly for the Halpha line core, where we have detected amplified emission from the stellar chromosphere after the source star's trailing limb exited the caustic. This achievement became possible by the provision of the very efficient OGLE-III Early Warning System, a network of small telescopes capable of nearly-continuous round-the-clock photometric monitoring, on-line data reduction, daily near-real-time modelling in order to predict caustic crossing parameters, and a fast and efficient response of a 8 m class telescope to a "Target-of-Opportunity" observation request},
  language  = {en}
}
@article{KubasCassanBeaulieuetal.2005,
  author    = {Kubas, Daniel and Cassan, A. and Beaulieu, Jean-Philippe and Coutures, C. and Dominik, M. and Albrow, Michael D. and Brillant, Stephane and Caldwell, John A. R. and Dominis, Dijana and Donatowicz, J. and Fendt, Christian and Fouque, P. and Jorgensen, Uffe Grae and Greenhill, John and Hill, K. and Heinm{\"u}ller, Janine and Horne, Keith and Kane, Stephen R. and Marquette, Jean-Baptiste and Martin, Ralph and Menzies, J. W. and Pollard, K. R. and Sahu, K. C. and Vinter, C. and Wambsganss, Joachim and Watson, R. and Williams, A. and Thurl, C.},
  title     = {Full characterization of binary-lens event OGLE-2002-BLG-069 from PLANET observations},
  issn      = {0004-6361},
  year      = {2005},
  abstract  = {We analyze the photometric data obtained by PLANET and OGLE on the caustic-crossing binary-lens microlensing event OGLE-2002-BLG-069. Thanks to the excellent photometric and spectroscopic coverage of the event, we are able to constrain the lens model up to the known ambiguity between close and wide binary lenses. The detection of annual parallax in combination with measurements of extended-source effects allows us to determine the mass, distance and velocity of the lens components for the competing models. While the model involving a close binary lens leads to a Bulge- Disc lens scenario with a lens mass of M = (0.51 ± 0.15) M-\⊙ and distance of D-L = (2.9 ± 0.4) kpc, the wide binary lens solution requires a rather implausible binary black-hole lens ( M \≳ 126 M-\⊙). Furthermore we compare current state-of-the-art numerical and empirical models for the surface brightness profile of the source, a G5III Bulge giant. We find that a linear limb-darkening model for the atmosphere of the source star is consistent with the data whereas a PHOENIX atmosphere model assuming LTE and with no free parameter does not match our observations},
  language  = {en}
}