Letter to the Editor

A quadruply imaged quasar with an optical Einstein ring candidate: 1RXS J113155.4–123155^*

¹ Institut d'Astrophysique et de Géophysique, ULg, Allée du 6 Août 17, B5C, 4000 Sart Tilman (Liège), Belgium
² European Southern Observatory, Alonso de Cordova 3107, Santiago 19, Chile
³ Royal Observatory of Belgium, Avenue Circulaire 3, 1180 Bruxelles, Belgium
⁴ Astronomical Observatory of Shevchenko University, 3 Observatorna st., Kyiv UA-04053, Ukraine

Corresponding author: D. Sluse, sluse@astro.ulg.ac.be

Received: 16 April 2003
Accepted: 14 June 2003

Abstract

We report the discovery of a new quadruply imaged quasar surrounded by an optical Einstein ring candidate. Spectra of the different components of 1RXS J113155.4-123155 reveal a source at . Up to now, this object is the closest known gravitationally lensed quasar. The lensing galaxy is clearly detected. Its redshift is measured to be . Additionally, the total V magnitude of the system has varied by 0.3 mag between two epochs separated by 33 weeks. The measured relative astrometry of the lensed images is best fitted with an SIS model plus shear. This modeling suggests very high magnification of the source (up to 50 for the total magnification) and predicts flux ratios between the lensed images significantly different from what is actually observed. This suggests that the lensed images may be affected by a combination of micro or milli-lensing and dust extinction effects.