Radio Flaring of the FSRQ B2 1420+32
ATel #17745; J. Hessdoerfer (University of Wurzburg), F. Eppel (JIVE), M. Kadler (University of Wurzburg), U. Bach (MPIfR), P. Benke (GFZ), A. Gokus (DESY), L. Haury (University of Wurzburg), S. Kim (KASI), F. Roesch (University of Wurzburg)
on 8 Apr 2026; 15:59 UT
Credential Certification: Florian Eppel (florian.eppel@uni-wuerzburg.de)
Subjects: Radio, Millimeter, Gamma Ray, TeV, VHE, Request for Observations, AGN, Blazar, Quasar
We report fast radio flaring of the TeV-detected flat-spectrum radio quasar B2 1420+32 (OQ 334) at high radio frequencies in the 14mm (19–25 GHz) and 7mm (36–44 GHz) bands, detected through regular observations within the TELAMON program (see Eppel et al. 2024, A&A, 684, A11).
We observed the source on 2026/04/01 and 2026/04/05 with the Effelsberg 100-m radio telescope and found the following flux densities, averaged over several sub-frequencies per band:
April 1, 2026
- 14mm: (2.02 ± 0.10) Jy
- 7mm: (2.44 ± 0.18) Jy
April 5, 2026
- 14mm: (2.56 ± 0.12) Jy
- 7mm: (3.44 ± 0.37) Jy
This corresponds to an increase in flux density of ~0.5 Jy and 1.0 Jy within only 5 days in the two bands, respectively. In its low state, the source showed significantly lower flux densities, reaching down to a minimum of (0.391 ± 0.011) Jy at 14mm and (0.478 ± 0.036) Jy at 7mm in our monitoring (August 28, 2022). B2 1420+32 has exhibited rapid radio flaring previously, but the current flare state is more than two times brighter than previous episodes (e.g., ATel#14822), when the source reached peak flux densities of (1.059 ± 0.012) Jy at 14mm and (1.26 ± 0.10) Jy at 7mm.
We note that the ongoing radio flaring might be associated to previous activity in the Fermi gamma-ray band (ATel#17504, ATel#17654).
The full light curve measured within the scope of the TELAMON program can be inspected on our website.
The TELAMON program uses the Effelsberg 100-m telescope to monitor the radio spectra of very-high-energy emitting active galactic nuclei (AGN), namely TeV blazars and candidate neutrino-associated AGN, with high-cadence high-frequency observations every ~3 weeks and at multiple frequencies up to 44 GHz. We will continue monitoring the source regularly and encourage further multi-messenger observations.
Link to TELAMON website
