Bibcode
DOI
Serra-Ricart, Miquel; Oscoz, Alejandro; Sanchís, Teresa; Mediavilla, E.; Goicoechea, Luis Julián; Licandro, Javier; Alcalde, David; Gil-Merino, Rodrigo
Bibliographical reference
The Astrophysical Journal, Volume 526, Issue 1, pp. 40-51.
Advertised on:
11
1999
Journal
Citations
32
Refereed citations
27
Description
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 δ2 test, is of 425+/-4 days, slightly
higher than the value previously accepted (417 days), but concordant
with the results obtained by other researchers.