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Astron. Astrophys. 327, L1-L4

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Letter to the Editor

HST confirmation of the lensed quasar J03.13*

J. Surdej1,**, J.-F. Claeskens1,***, M. Remy1, S. Refsdal2, B. Pirenne3, A. Prieto4, and Ch. Vanderriest5

1Institut d'Astrophysique, Université de Liège, Avenue de Cointe 5, B-4000 Liège, Belgium
2Hamburg Observatory, Gojenbergsweg 112, D-21029 Hamburg, Germany
3ST-ECF, c/o ESO, Karl-Schwarzschild Str. 2, D-85748 Garching bei München, Germany
4MPI für Extraterrestrische Physik, Giessenbachstrasse, D-85748 Garching bei München, Germany
5Observatoire de Meudon, Place Jules Janssen 5, F-92195 Meudon PRINCIPAL CEDEX, France

Received 5 August 1997 / Accepted 29 August 1997


In order to definitely prove the claim by Claeskens et al. (1996) that J03.13 is a doubly imaged quasar, WFPC2 direct imaging and FOS spectroscopy of this compact system have been obtained with HST. These textbook case observations clearly show that J03.13 consists of two point-like images separated by 0.849FORMULA FORMULA 0.001FORMULA with a magnitude difference of 2.14 FORMULA 0.03 in V and I. We see no trace of a lensing galaxy. From the FOS observations, we find that J03.13 A and B have identical spectra within the measurement uncertainties. The data also show that spectroscopic contamination of B by A is negligible. We do confirm the redshift z = 2.545 for J03.13 A and B (emission-lines due to LyFORMULA FORMULA1025 and OVI FORMULA1031, 1037 are also detected), first derived from an unresolved ground-based spectrum of the two components by Claeskens et al. We also find that the absorption line system at z = 2.344 (CIV and LyFORMULA) is present in the spectra of A and B. On the contrary, the absorption line system at z = 1.085 (MgII) is only present in the spectrum of J03.13 A. If this latter system is associated with the lens, we may expect that image A consists of two radially merging images with a very small angular separation. From the WFPC2 imagery, we can rule out the presence of a third component fainter than A by up to 5.2 mag. with an angular separation FORMULA 0.13FORMULA.

Key words: - gravitational lensing - quasars: individual: J03.13 - Techniques: image processing

*Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.
**Directeur de Recherches du FNRS, Belgium
***Aspirant du FNRS, Belgium

Send offprint requests to: J. Surdej (e-mail: surdej@astro.ulg.ac.be)

© European Southern Observatory (ESO) 1997

Online publication: October 14, 1997
Last change: April 6, 1998