Detection of an increase in the flux density at 43 GHz from blazar PKS 1510-089 since August, 2011

ATel #3799; P. P. Beaklini (IAG/USP), Z. Abraham (IAG/USP), T. P. Dominici (MCTI/LNA)
on 8 Dec 2011; 23:43 UT
Credential Certification: Tania Dominici (tdominici@lna.br)

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We have been performing monthly observations of PKS1510-089 at 43 GHz since 2011 January, using the Itapetinga Radio telescope (13.7 m antenna installed at Atibaia, Brazil). We already reported the variability behavior during the July gamma ray flare (ATel #3523, following the communication from Atel #3470 and Atel #3473,). In the occasion, the blazar was relatively bright at 43 GHz, but we concluded that the source behavior was not different from the observed since the beginning of the year(Atel #3523).

After July, PKS 1510-089 reached an even higher flux density at gamma-ray frequencies, as detected by Fermi/LAT (Atel #3694). The high energy activity was followed by a high flux increase at radio frequencies, as reported by Nestoras et al. and Orienti et al. (Atel#3698, Atel #3775, respectively). Nestoras et al. also pointed out the occurrence of many short term sub-flares superposed on the long term variations (Atel #3698)

Our data show the detection of a progressively increase in the flux density at 43 GHz during the second semester of 2011. After a maximal in August 28 of 5.34+/-0.44 Jy, the source decreased to 3.85+/-0.40 Jy in August 30, until start to become brighter. In September, the source density flux was 4.84 +/- 0.39 Jy on the day 26 and 4.87+/-0.51 Jy on the day 29. In October 28, the value was 5.04 +/- 0.46 Jy and in November 26 it was 6.09+/-0.56 Jy. At last, after 3 days, the flux density reached 6.59 +/-0.99 Jy.

During the first semester of 2011, the source never was detected with flux densities larger than 4 Jy at 43 GHz. The radio activity started to increase after the beginning of the gamma ray flares. We will continue the monitoring of PKS 1510-089 and we encourage further multifrequency observations of this source.