Bright optical/GeV-ray flares in Blazars PKS 1424-418 and PKS 1406-076

ATel #15525; F. Jankowsky, S. J. Wagner, F. Ait-Benkhali (LSW Heidelberg)
on 23 Jul 2022; 23:10 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Stefan J. Wagner (swagner@lsw.uni-heidelberg.de)

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Optical observations of the PKS 1424-418 (z=1.522, White et al., ApJ, 327, 561 (1988)) with the Automatic Telescope for Optical Monitoring (ATOM) in Namibia reveal this Blazar in a bright optical state. Preliminary analysis of measurements performed on July 23 2022 (MJD 59783.8) show a peak R magnitude of 13.4 with 0.1 mag variations within one hour. This is 4.6 magnitudes brighter than the lowest flux measured during the last 15 years. PKS 1424-418 underwent a steady increase in brightness by 1.2 magnitudes since July 15, 2022 (MJD 59775.2). The optical flare is 0.9 mag brighter than an earlier outburst observed in May 2010, with a coincident GeV Gamma-ray flare (ATEL #2613, Buson et al., AA 569, A40 (2014)).

The flare observed in the optical band coincides with an increase of gamma-ray flux recorded in the 100 MeV - 500 GeV band with the Fermi-LAT instrument reaching a level of 3.5 10^-6 cm^-2 s^-1 on July 22 2022, exceeding the flux of the 2013 flare which has been the brightest flare in the LAT band so far.

Optical observations of the Blazar PKS 1406-076 (z=1.494, Wilkes et al., PASA, 5, 2 (1983)) with ATOM show this Blazar in a bright optical state. Preliminary analysis of measurements performed on July 23 2022 (MJD 59783.8) show a peak R magnitude of 16.2. This is 3 magnitudes brighter than the lowest flux measured during the last 15 years. PKS 1406-076 underwent a steady increase in brightness by 1.7 magnitudes since May 24, 2022 (MJD 59723.8). This is the brightest flare recorded with ATOM during the past 15 years.

Further multi-frequency observations of these outbursts are encouraged. ATOM is a 75cm optical telescope located at the H.E.S.S. site in Namibia. Fermi-LAT fluxes are available also on the public LAT light curve page.

public LAT light curve page