References of "Poels, Joël"
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See detailThe International Liquid Mirror Telescope (ILMT) as a Variability Time Machine
Poels, Joël ULg; Borra, Ermanno; Hickson, Paul et al

in Griffin, Elisabeth (Ed.) New Horizons In Time-Domain Astronomy, IAU Symposium No. 285, 2011 (2011)

During the year 2012 the International Liquid Mirror Telescope (a collaboration between astronomical institutions in Belgium, Canada, India and Poland) will see first light. The instrument will provide ... [more ▼]

During the year 2012 the International Liquid Mirror Telescope (a collaboration between astronomical institutions in Belgium, Canada, India and Poland) will see first light. The instrument will provide substantial, in-depth sky coverage and make an unprecedented number of nightly observations. [less ▲]

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See detailFlux and color variations of the quadruply imaged quasar HE 0435--1223
Ricci, Davide ULg; Poels, Joël ULg; Elyiv, Andrii ULg et al

in Astronomy and Astrophysics (2011), 528

We present VRi photometric observations of the quadruply imaged quasar HE 0435-1223, carried out with the Danish 1.54m telescope at the La Silla Observatory. Our aim was to monitor and study the ... [more ▼]

We present VRi photometric observations of the quadruply imaged quasar HE 0435-1223, carried out with the Danish 1.54m telescope at the La Silla Observatory. Our aim was to monitor and study the magnitudes and colors of each lensed component as a function of time. methods: We monitored the object during two seasons (2008 and 2009) in the VRi spectral bands, and reduced the data with two independent techniques: difference imaging and PSF (Point Spread Function) fitting.results: Between these two seasons, our results show an evident decrease in flux by ~0.2-0.4 magnitudes of the four lensed components in the three filters. We also found a significant increase (~0.05-0.015) in their V-R and R-i color indices. conclusions: These flux and color variations are very likely caused by intrinsic variations of the quasar between the observed epochs. Microlensing effects probably also affect the brightest "A" lensed component. [less ▲]

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See detailHE 0435-1223 lensed QSO VRi light curves (Ricci+, 2011)
Ricci, Davide ULg; Poels, Joël ULg; Elyiv, Andrii ULg et al

Textual, factual or bibliographical database (2011)

We present VRi photometric observations of the quadruply imaged quasar HE0435-1223, carried out with the Danish 1.54m telescope at the La Silla Observatory. Our aim was to monitor and study the magnitudes ... [more ▼]

We present VRi photometric observations of the quadruply imaged quasar HE0435-1223, carried out with the Danish 1.54m telescope at the La Silla Observatory. Our aim was to monitor and study the magnitudes and colors of each lensed component as a function of time. [less ▲]

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See detailRadial velocities with the Gaia RVS spectrometer
Viala, Y. P.; Blomme, R.; Damerdji, Yassine ULg et al

in Charbonnel, C.; Combes, F.; Samadi, R. (Eds.) SF2A-2008; Annual Meeting of the French Society of Astronomy (2008, November 01)

Four different method are used to derive radial velocities from spectra observed by the Gaia Radial Velocity Spectrometer (RVS). They are briefly presented here together with very preliminary results.

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See detailGravitational Lensing, Dark Matter and the Optical Gravitational Lens Experiment
Surdej, Jean ULg; Claeskens, Jean-François ULg; Delacroix, Christian ULg et al

in Matagne, N.; Cugnon, Joseph; Lansberg, Jean-Philippe (Eds.) American Institute of Physics Conference Proc. Volume 1038 (2008, August 01)

After briefly reviewing the history of gravitational lensing, we recall the basic principles of the theory. We then describe and use a simple optical gravitational lens experiment which has the virtue of ... [more ▼]

After briefly reviewing the history of gravitational lensing, we recall the basic principles of the theory. We then describe and use a simple optical gravitational lens experiment which has the virtue of accounting for all types of image configurations observed so far among the presently known gravitational lens systems. Finally, we briefly present the 4m International Liquid Mirror Telescope project in the context of a photometric monitoring of multiply imaged quasars. [less ▲]

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See detailThe 4m international liquid mirror telescope (ILMT)
Surdej, Jean ULg; Absil, Olivier ULg; Bartczak, Przemyslaw ULg et al

in Stepp, Larry (Ed.) Ground-based and Airborne Telescopes (2006, July 01)

The entire funding has recently been obtained in Belgium for the construction of a 4m Liquid Mirror Telescope. Its prime focus will be equipped with a semi-conventional glass corrector allowing to correct ... [more ▼]

The entire funding has recently been obtained in Belgium for the construction of a 4m Liquid Mirror Telescope. Its prime focus will be equipped with a semi-conventional glass corrector allowing to correct for the TDI effect and a thinned, high quantum efficiency, 4K × 4K pixel equivalent CCD camera. It will be capable of subarcsecond imaging in the i'(760 nm) and possibly r', g' band(s) over a field of ~ 30' in diameter. This facility will be entirely dedicated to a deep photometric and astrometric variability survey over a period of ~ 5 years. In this paper, the working principle of liquid mirror telescopes is first recalled, along with the advantages and disadvantages of the latter over classical telescopes. Several science cases are described. For a good access to one of the galactic poles, the best image quality sites for the ILMT are located either in Northern Chile (latitude near -29°30') or in North-East India (Nainital Hills, latitude near +29°30'). At those geographic latitudes, a deep (i' = 22.5 mag.) survey will approximately cover 90 square degrees at high galactic latitude, which is very useful for gravitational lensing studies as well as for the identification of various classes of interesting galactic and extragalactic objects (cf. microlensed stars, supernovae, clusters, etc.). A description of the telescope, its instrumentation and the handling of the data is also presented. [less ▲]

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See detailPhotometric monitoring of the doubly imaged quasar UM 673: possible evidence for chromatic microlensing
Nakos, Theodoros; Courbin, F.; Poels, Joël ULg et al

in Astronomy and Astrophysics (2005), 441

We present the results of two-band CCD photometric monitoring of the gravitationally lensed quasar Q 0142-100 (UM 673). The data, obtained at ESO-La Silla with the 1.54 m Danish telescope in the Gunn i ... [more ▼]

We present the results of two-band CCD photometric monitoring of the gravitationally lensed quasar Q 0142-100 (UM 673). The data, obtained at ESO-La Silla with the 1.54 m Danish telescope in the Gunn i-band (October 1998-September 1999) and in the Johnson V-band (October 1998 to December 2001), were analyzed using three different photometric methods. The light-curves obtained with all methods show variations, with a peak-to-peak amplitude of 0.14 mag in V. Although it was not possible to measure the time delay between the two lensed QSO images, the brighter component displays possible evidence for microlensing: it becomes bluer as it gets brighter, as expected under the assumption of differential magnification of a quasar accretion disk. [less ▲]

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See detailThe 4-m International Liquid Mirror Telescope Project (ILMT) (poster)
Poels, Joël ULg; Borra, E.; Claeskens, Jean-François ULg et al

in Harnden, F. R.; Primini, F. A.; Payne, H. E. (Eds.) Astronomical Data Analysis Software & Systems X Conference (2001)

The working principle of liquid mirror telescopes (LMTs) is first reviewed along with their advantages and disadvantages over classical telescopes. For several reasons (access to regions near the south ... [more ▼]

The working principle of liquid mirror telescopes (LMTs) is first reviewed along with their advantages and disadvantages over classical telescopes. For several reasons (access to regions near the south galactic pole, galactic center, good image quality, etc.), an excellent site for such an LMT is the Atacama desert. A deep (B~24 mag) LMT survey at latitudes near -22deg -- -29deg will cover ~90 square degrees at high galactic latitude and be especially useful for gravitational lensing studies, for the identification of various classes of interesting extragalactic objects (cf. clusters, supernovae, etc. at high redshift) and for subsequent follow-up observations with 8 m-class telescopes. A short description of the handling of data products is also presented. [less ▲]

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See detailSurveys with the 4-m International Liquid Mirror Telescope
Poels, Joël ULg; Moreau, O.; Manfroid, Jean ULg et al

in Mining the Sky (2001)

The working principle of liquid mirror telescopes (LMTs) is first reminded as well as their advantages and disadvantages over classical telescopes. For several obvious reasons (access to regions near the ... [more ▼]

The working principle of liquid mirror telescopes (LMTs) is first reminded as well as their advantages and disadvantages over classical telescopes. For several obvious reasons (access to regions near the south galactic pole, galactic center, good image quality, ...), a best site location for such a LMT is somewhere in the Atacama desert. At latitudes near -22 - -29 degree, a deep (B = 24 mag.) LMT survey will approximately cover 90 square degrees at high galactic latitude, specially useful for gravitational lensing studies, for the identification of various classes of interesting extragalactic objects (cf. clusters, supernovae, etc. at high redshift) and subsequent follow-up observations with 8m-class telescopes. A short description of the handling of data products is also presented. [less ▲]

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See detailSurveys with the 4-m International Liquid Mirror Telescope Project (ILMT) (poster)
Poels, Joël ULg; Moreau, O.; Manfroid, Jean ULg et al

in Banday, A. J.; Zaroubi, S.; Bartelmann, M. (Eds.) Astronomical Data Analysis Software and Systems X (2001)

The working principle of liquid mirror telescopes (LMTs) is first reviewed along with their advantages and disadvantages over classical telescopes. For several reasons (access to regions near the south ... [more ▼]

The working principle of liquid mirror telescopes (LMTs) is first reviewed along with their advantages and disadvantages over classical telescopes. For several reasons (access to regions near the south galactic pole, galactic center, good image quality, etc.), an excellent site for such an LMT is the Atacama desert. A deep (B~24 mag) LMT survey at latitudes near -22deg -- -29deg will cover ~90 square degrees at high galactic latitude and be especially useful for gravitational lensing studies, for the identification of various classes of interesting extragalactic objects (cf. clusters, supernovae, etc. at high redshift) and for subsequent follow-up observations with 8 m-class telescopes. A short description of the handling of data products is also presented. [less ▲]

Detailed reference viewed: 43 (14 ULg)