A prominent fluctuation in the optical brightness of Q0957+561A and prediction of the Q0957+561B optical variability in the first semester of 2010
ATel #2228; Luis J. Goicoechea (Universidad de Cantabria, Spain) and Vyacheslav N. Shalyapin (Institute for Radiophysics and Electronics, Ukraine)
on 5 Oct 2009; 19:31 UT
Credential Certification: Luis J. Goicoechea (goicol@unican.es)
Subjects: Optical, Request for Observations, AGN, Quasar, Transient
We are conducting a long-term monitoring of the optical magnitudes of
gravitationally lensed quasars using the 2.0 m Liverpool Robotic Telescope
at the Roque de los Muchachos Observatory (Canary Islands, Spain). This
Liverpool Quasar Lens Monitoring (LQLM) programme includes several lensed
quasars whose images are as bright as or brighter than 19 mag in the
r-band (SDSS photometric system). One of our targets is Q0957+561
(RA=10:01:20.78, Dec=+55:53:49.4), which consists of two images of the
same distant quasar at z=1.41. These images Q0957+561A and Q0957+561B are
separated by about 6 arcsec. From the LQLM photometric pipelines (Shalyapin
et al. 2008, A&A, 492, 401), we detected a strong quasar activity over the
last three years. In particular, the g-band flux of the leading image
Q0957+561A increases 30% just after a deep minimum, i.e., it changes
from g~17.45 to g~17.15 over about 130 days. We also observe a significant
increase (~20%) in the r-band flux of Q0957+561A, which confirms the
existence of an optical event. The most recent LQLM observations of
Q0957+561A (first semester of 2009) show this event has peaked and later
decreased in brightness.
As the the prominent fluctuation in the optical brightness of Q0957+561A
occured berween late 2008 and the middle of 2009, it is expected a similar
fluctuation in the light curve of the trailing image Q0957+561B in the first
semester of 2010, starting in early February and reaching its maximum in June
(taking a time delay of about 14 months into account; the g-band brightening
of Q0957+561B will probably behave like the red circles between the two
vertical blue arrows in the figure http://grupos.unican.es/glendama/ATel.png ).
Consequently, we strongly encourage multiwavelength observations of
Q0957+561B. Although we will try to monitor this target in 2010 in the g and
r bands (and perhaps using other optical/NIR filters), additional
spectrophotometry at X-ray, UV, optical, IR and radio wavelengths should play
a crucial role in the understanding of the variability mechanism and other
aspects of the distant source. For example, it could be possible to
accurately check if the observed optical event (which corresponds to middle
UV emission at the redshift of the quasar) is triggered (and thus preceded)
by a higher energy flare.
GLENDAMA project
