References of "Courbin, Frédéric"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailCOSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses: XII. Time delays of the doubly lensed quasars SDSS~J1206+4332 and HS~2209+1914
Eulaers, Eva ULg; Tewes, Malte; Magain, Pierre ULg et al

in Astronomy and Astrophysics (2013)

Aims. Within the framework of the COSMOGRAIL collaboration we present 7- and 8.5-year-long light curves and time-delay esti- mates for two gravitationally lensed quasars: SDSS J1206+4332 and HS 2209+1914 ... [more ▼]

Aims. Within the framework of the COSMOGRAIL collaboration we present 7- and 8.5-year-long light curves and time-delay esti- mates for two gravitationally lensed quasars: SDSS J1206+4332 and HS 2209+1914. Methods. We monitored these doubly lensed quasars in the R-band using four telescopes: the Mercator, Maidanak, Himalayan Chandra, and Euler Telescopes, together spanning a period of 7 to 8.5 observing seasons from mid-2004 to mid-2011. The pho- tometry of the quasar images was obtained through simultaneous deconvolution of these data. The time delays were determined from these resulting light curves using four very different techniques: a dispersion method, a spline fit, a regression difference technique, and a numerical model fit. This minimizes the bias that might be introduced by the use of a single method. Results. The time delay for SDSS J1206+4332 is ∆tAB = 111.3 ± 3 days with A leading B, confirming a previously published result within the error bars. For HS 2209+1914 we present a new time delay of ∆tBA = 20.0 ± 5 days with B leading A. Conclusions. The combination of data from up to four telescopes have led to well-sampled and nearly 9-season-long light curves, which were necessary to obtain these results, especially for the compact doubly lensed quasar HS 2209+1914. [less ▲]

Detailed reference viewed: 16 (1 ULg)
Full Text
See detailCOSMOGRAIL: Measuring Time Delays of Gravitationally Lensed Quasars to Constrain Cosmology
Tewes, Malte; Courbin, Frédéric; Meylan, Georges et al

in The Messenger (2012)

COSMOGRAIL is a long-term programme for the photometric monitoring of gravitationally lensed quasars. It makes use of several medium-size telescopes to derive long and well-sampled light curves of lensed ... [more ▼]

COSMOGRAIL is a long-term programme for the photometric monitoring of gravitationally lensed quasars. It makes use of several medium-size telescopes to derive long and well-sampled light curves of lensed quasars, in order to measure the time delays between the quasar images. These delays directly relate to the Hubble constant H0, without any need for secondary distance calibrations. COSMOGRAIL was initiated in 2004, and has now secured almost a decade of data, resulting in cosmological constraints that are very complementary to other cosmological probes. [less ▲]

Detailed reference viewed: 30 (3 ULg)
Full Text
See detailThe Host Galaxies of the Brightest Quasars: Gas-Rich Galaxies, Mergers, and Young Stars
Courbin, Frédéric; Letawe, Géraldine ULg; Meylan, Georges et al

in The Messenger (2006), 124

Because they are faint and hidden in the glare of a much brighter unresolved source, quasar host galaxies still challenge the most powerful telescopes, instrumentation and processing techniques ... [more ▼]

Because they are faint and hidden in the glare of a much brighter unresolved source, quasar host galaxies still challenge the most powerful telescopes, instrumentation and processing techniques. Determining their basic morphological parameters and their integrated colours is feasible, but difficult, from imaging alone. However, detailed information on their stellar and gas contents and on their dynamics is achievable with deep spectroscopy. [less ▲]

Detailed reference viewed: 20 (2 ULg)
Full Text
Peer Reviewed
See detailHigh precision photometry in crowded stellar fields
Magain, Pierre ULg; Courbin, Frédéric; Gillon, Michaël ULg et al

in SPIE Newsroom (2006)

A deconvolution-based method which allows to derive high-precision photometry of stars in crowded fields, proves very useful for a variety of astronomical projects, including transit searches for ... [more ▼]

A deconvolution-based method which allows to derive high-precision photometry of stars in crowded fields, proves very useful for a variety of astronomical projects, including transit searches for extrasolar planets. [less ▲]

Detailed reference viewed: 24 (3 ULg)