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Recent radio activity of the Fermi blazar 4C +38.41

ATel #4448; I. Myserlis, E. Angelakis, L. Fuhrmann, V. Karamanavis, I. Nestoras, T. P. Krichbaum, J. A. Zensus (F-GAMMA team, MPIfR, Bonn, Germany), H. Ungerechts, A. Sievers (IRAM, Granada, Spain)
on 2 Oct 2012; 12:13 UT
Credential Certification: Emmanouil Angelakis (angelaki@mpifr-bonn.mpg.de)

Subjects: Radio, Millimeter, AGN, Blazar, Quasar

Abstract:
We report the recent activity (raising flux density) seen in the monitored blazar 4C +38.41 (J1635+3808, RA= 16:35:16, DEC=+38:08:05 in J2000), as recorded within the framework of the F-GAMMA program responding to ATels #4389, #4400 and #4437 (gamma, NIR and optical respectively).

Long term behaviour:
4C +38.41 has been monitored since January 2007 at 11 frequencies between 2.64 and 228.39 GHz. It has shown a major event characterized by long term behaviour dominating the frequencies below 10.45 GHz, while at higher frequencies events of significantly shorter time scales occur, as it can be seen in its light curves at: low, intermediate and higher radio frequencies (or all frequencies together). The source's radio spectrum remains predominantly flat as it can be seen in the animation of the temporal evolution of its spectrum.

Recent activity:
The high frequencies light curves show a new activity phase. After a short minimum between MJD 55950 and 56050, the flux density started an increasing trend. For example, at 32.00 GHz (9 mm) the flux density increased from 2.4 (MJD: 56009.055) to 5.2 Jy (MJD: 56185.514). At intermediate frequencies the behaviour is similar to the higher ones showing only a small delay. At low frequencies the delay seems to be larger since the 2.64 GHz flux density is at the minimum even at MJD: 56172.993. The weekly-averaged public Fermi light curve (100 MeV - 300 GeV) indicates an ongoing outburst that started around MJD: 56100, a behaviour similar to the radio frequencies.

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 simultaneously within 40 minutes for Effelsberg and 10 minutes for the IRAM telescope while the cross-station coherency is of order of 10 days. Data products are publicly accessible here. For more details, visit:

F-GAMMA program page