Enhanced 24 GHz flux density from 3C 380
ATel #14012; N. Marchili, S. Righini, M. Giroletti (INAF/IRA), E. Egron, D. Perrodin (INAF/OACagliari), P. Grandi, E. Torresi (INAF/OAS)
on 15 Sep 2020; 15:20 UT
Credential Certification: Marcello Giroletti (giroletti@ira.inaf.it)
Subjects: Radio, Gamma Ray, >GeV, AGN, Blazar, Quasar
We report about the radio behaviour of the radio quasar 3C 380, as a result of our ongoing monitoring program with the 32m Medicina Radio Telescope and the 64m Sardinia Radio Telescope (SRT), both operated by INAF. Interest in this source has been rising following the detection of increased gamma-ray activity in the beginning of September 2020 (ATel #13999) by the Large Area Telescope (LAT) onboard the Fermi Gamma-ray Space Telescope.
3C 380 (z=0.692) is part of our blazar monitoring program since 2012. Three K-band (24 GHz) observations are available for 2020: we measured a flux density of 3.00 +/- 0.15 Jy on February the 29th (MJD 58908), of 2.80 +/- 0.20 Jy on August the 12th (MJD 59073), and of 2.75 +/- 0.15 Jy on September the 11th (MJD 59103). All three values are significantly higher than the ones found in 2019, a year for which 8 measurements are available between February and November, ranging from 2.13 Jy to a maximum of 2.48 Jy, with an average of 2.28 Jy. The sparseness of 2020's observations does not allow us to precisely define the time of the 24 GHz flux density peak, which cannot be excluded to fall in the first half of 2020. Further observations of 3C 380 are also planned in the future, with a monthly cadence, in order to better constrain its variability features.
We would like to thank the SRT Director and scheduler for offering us the chance to carry on our observational campaigns during the time in which the Medicina 32m telescope was unavailable due to maintenance works.
