Radio re-brightening of the gamma-ray flaring blazar PKS 1510-089

ATel #3500; L. Fuhrmann, E. Angelakis, I. Nestoras, R. Schmidt, T. P. Krichbaum, J. A. Zensus (F-GAMMA team, MPIfR, Bonn, Germany), H. Ungerechts, A. Sievers, D. Riquelme (IRAM, Granada, Spain)
on 19 Jul 2011; 10:54 UT
Credential Certification: Lars Fuhrmann (lfuhrmann@mpifr-bonn.mpg.de)

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Responding to the ATels #3473 and #3470 reporting the recent flaring activity of PKS 1510-089 at gamma-rays beginning of July 2011 as well as ATel #3479 reporting no optical counterpart of this activity, we here report its behavior at radio bands as observed by the F-GAMMA program.

Long-term activity:
Observations performed with the Effelsberg 100-m and the IRAM 30-m telescope since its pronounced flaring activity of 2009 show that the source is basically following a continuously decaying long-term trend at low to intermediate frequencies, though with smaller "sub-flares" superimposed. The last one of those peaked beginning of 2011 and was most pronounced at short-mm bands. Subsequently, this "sub-flare" decreased reaching a minimum around June 2011 at cm-bands with flux levels of e.g. 1.48+/-0.02, 1.67+/-0.04 and 1.76+/-0.12 Jy at 2.6, 15 and 23 GHz, respectively.

Recent activity:
Our last Effelsberg observations of July 8, 2011 indicate, however, that the flux densities at cm-bands are inverting their behavior again also showing a pronounced increase compared to June 2011 maybe related to the recent activity of the source at gamma-rays. At nearly all frequencies (from 2.6 up to 23 GHz) the flux densities increased to e.g. 1.55+/-0.03, 2.07+/-0.08 and 2.56+/-0.2 Jy at 2.6, 15 and 23 GHz, respectively. The radio light curves can be accessed separately at low, intermediate and high frequencies. Alternatively, also the evolution of its spectrum as a function of time can be accessed.

The source will be continuously monitored and possible future activity will be reported through the current platform.

F-GAMMA program:
F-GAMMA (Fermi-GST AGN Multi-frequency Monitoring Alliance) program is the coordinated effort of several observatories and research teams to probe AGN physics through the multi-frequency monitoring approach. The core program relies on monthly observations with the Effelsberg 100-m radio telescope (operating at 8 frequencies between 2.6 and 43 GHz), the IRAM 30-m telescope (observing at 86 and 142 GHz) and additional measurements with the APEX 12-m telescope (operating at 345 GHz). The core sample consists of roughly 60 Fermi-GST/LAT monitored blazars. The data are taken quasi-simultaneously within 40 minutes for Effelsberg and truly simultaneous at the IRAM telescope while the cross-station coherency is of order of 10 days. Data products are publicly accessible here.