Astronomy and Astrophysics, volume 317, L39 (1997/1-1)
Detection of a spiral lens galaxy and optical variability in the gravitational lens system B1600+434.
JAUNSEN A.O. and HJORTH J.
Abstract (from CDS):
The gravitationally lensed quasar B1600+434 (z=1.61, mv=21.6) has been observed at the 2.56m Nordic Optical Telescope (NOT). In this Letter we report the discovery of an edge-on late-type galaxy located between the two lensed components (separation 1.4"), close to the fainter image. The galaxy photometry indicates that its redshift is approximately 0.4. We detect a large colour difference between the two images due to significant obscuration of the faint image. The estimated amount of absorption as a function of colour indicates that the extinction may be due to dust in the lensing galaxy. We also present evidence of flux variability in B1600+434 with a detected change of ∼0.25mag in one year. The theoretically expected time delay is of the order of one month and so the system may be an interesting object for determining the Hubble constant.