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Record cm/mm-band radio flux levels of the gamma-ray flaring blazar PKS 1510-089

ATel #3698; I. Nestoras, L. Fuhrmann, E. Angelakis, R. Schmidt, T. P. Krichbaum, J. A. Zensus (F-GAMMA team, MPIfR, Bonn, Germany), H. Ungerechts, A. Sievers, D. Riquelme (IRAM, Granada, Spain)
on 21 Oct 2011; 19:02 UT
Credential Certification: Ioannis Nestoras (inest@mpifr-bonn.mpg.de)

Subjects: Radio, Millimeter, AGN

Referred to by ATel #: 3775, 3799

Responding to the ATel #3694 reporting the recent flaring activity of PKS 1510-089 at gamma-rays mid of October 2011, we here report its latest behavior at radio bands (cm to mm) as observed by the F-GAMMA program. Previous activity of the source at radio bands have been reported in ATels #3500 and #3523.

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 was 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. 1.42+/-0.01, 1.67+/-0.04 and 1.76+/-0.12 Jy at 4.9, 15 and 23 GHz, respectively. At mm-bands the latest minimum occurred around March 2011 with flux levels of 1.67+/-0.06 Jy and 1.24+/-0.07 Jy at 86 and 142 GHz respectively. Subsequently, as reported in ATel #3500, the flux densities at cm-bands inverted their behavior showing a pronounced increase compared to June 2011.

Recent activity:
Indeed, our latest Effelsberg observations of September 30, 2011 and IRAM 30-m observations of October 7, 2011 demonstrate that the flux densities at cm and mm-bands further increased and now turned into an extreme and rapid outburst most likely related to the recent extreme activity of the source at gamma-rays. In particular, at mm-bands the source shows the highest ever recorded flux densities - at least as observed over the last 5 years by the F-GAMMA program. The same is observed at 23 GHz. At lower frequencies the source also shows increased activity. The observed flux density levels are 1.52+/-0.02, 3.51+/-0.08 and 5.02+/-0.22 Jy at 4.9, 15 and 23 GHz, respectively. At frequencies above 23 GHz, the source has increased to flux levels of 6.03+/-0.36 Jy, 6.86+/-0.42 Jy and 4.2+/-1.9 Jy at 32, 86 and 142 GHz respectively. Consequently, the source spectrum currently peaks at around 86 GHz. 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.