1999/06/10 by M. Serra-Ricart, Miquel Serra‐Ricart, A. Oscoz +13 · 1 citation
Physics and Astronomy · #Adaptive optics and wavefront sensing #Astronomy and Astrophysical Research #Data reduction #Gravitational lens #Homogeneity (statistics) #Lens (geology) #Light curve #Photometry (optics) #Stellar, planetary, and galactic studies #Telescope #astro-ph
paper · pdf · doi:10.1086/307961
31 pages, 16 figures, accepted for publication in ApJ
arxiv created 1999/06/10 · openalex publication_date 1999/11/20 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
CCD observations of the gravitational lens system Q0957+561A, B in the BVRI bands are presented in this paper. The observations, taken with the 82 cm IAC-80 telescope at Teide Observatory, Spain, were made from the beginning of 1996 February to 1998 July, as part of an ongoing lens-monitoring program. Accurate photometry was obtained by simultaneously fitting a stellar two-dimensional profile on each component by means of DAOPHOT software. This alternative method is equal to and even improves on the results obtained with previous techniques. The final data set is characterized by its high degree of homogeneity, since it was obtained using the same telescope and instrumentation during a period of almost 3 yr. The resulting delay, obtained with a new method, the δ 2 test, is of 425 ± 4 days, slightly higher than the value previously accepted (417 days), but concordant with the results obtained by other researchers.