Astronomy and astrophysics

Publication date: 1996-05-01
Volume: 309 Pages: 59 - 64
Publisher: Springer verlag

Author:

Ostensen, Roy
Refsdal, S ; Stabell, R ; Teuber, J ; Emanuelsen, PI ; Festin, L ; FlorentinNielsen, R ; Gahm, G ; Gullbring, E ; Grundahl, F ; Hjorth, J ; Jablonski, M ; Jaunsen, AO ; Kaas, AA ; Karttunen, H ; Kotilainen, J ; Laurikainen, E ; Lindgren, H ; Mahonen, P ; Nilsson, K ; Olofsson, G ; Olsen, O ; Pettersen, BR ; Piirola, V ; Sorensen, AN ; Takalo, L ; Thomsen, B ; Valtaoja, E ; Vestergaard, M ; Vianborg, TA

Keywords:

gravitational lensing, techniques, image processing, quasars, q 2237+0305, gravitational lens, stellar photometry, light-curve, system, q2237+0305, variability, image, Science & Technology, Physical Sciences, Astronomy & Astrophysics, quasars, Q 2237+0305, GRAVITATIONAL LENS, STELLAR PHOTOMETRY, LIGHT-CURVE, SYSTEM, Q2237+0305, VARIABILITY, IMAGE, 0201 Astronomical and Space Sciences, 5101 Astronomical sciences, 5107 Particle and high energy physics, 5109 Space sciences

Abstract:

We report results from five years of monitoring of the Einstein Cross (QSO 2237+0305) with the Nordic Optical Telescope, The photometry, mainly in the R and I bands, has been performed by a PSF fitting and 'cleaning' procedure, in which the four image components as well as the host galaxy and its nucleus are iteratively removed. The resulting lightcurves exhibit several microlensing features; one event may have a timescale as short as 14 days. Variations on timescales of several years are found in all four images. This becomes even more convincing when our data are combined with data published for 1986-89. No clear high amplification event was observed during the period. A brightening of all four components during 1994 is interpreted as intrinsic variation.