Old Q0957+561 data & software:
► Simple FORTRAN programs to apply the d2 test (accurate and robust time delay measurements)
► Photos
Advertising:
FBQ 0951+2635
OPTICAL MONITORING: Since 2007 February, this double quasar is being monitored with LRT (Liverpool Robotic Telescope) in the i band. The main goal is to study the probable extrinsic variability at large wavelengths, and to compare it with the observed extrinsic signal at shorter wavelengths (Paraficz et al. 2006). Each observation consists of five exposures of 100 sec, using a dither cross pattern. The 'cross' is done from offsets of + 10" and - 10" in both RA and declination. Five subframes associated with the five exposures on February 7 (FWHM of the seeing disc = 1") are depicted in the FIGURE. The lens system appears as an elongated structure (in comparison to the nearby point-like sources) in all these subframes: it is enclosed in a green circle.
(click on the figure to enlarge)