Elevated fluxes at multiple radio frequencies seen in flaring blazar PKS 0454-234

ATel #3713; Michael Gaylard (HartRAO), Marion West (HartRAO), Philip Edwards (CSIRO Astronomy and Space Science), Jamie Stevens (CSIRO Astronomy and Space Science), Roopesh Ojha (NASA/GSFC) and Faith Hungwe (Rhodes U., HartRAO)
on 26 Oct 2011; 13:49 UT
Credential Certification: Roopesh Ojha (Roopesh.Ojha@gmail.com)

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The report of sustained and increasing gamma-ray activity of the blazar PKS 0454-234 (ATel #3703) has inspired follow-up radio observations of this source.

The Hartebeesthoek Radio Astronomy Observatory (HartRAO) 26m telescope was used to measure the flux density of PKS0454-234 between 2011 October 25 at 2240 UTC and October 26 at 0246UTC. Two drift scans were made in each band, on either side of zenith meridian transit. Pointing errors in Declination were checked by scans through the half-power points of the beam at the three higher frequencies. Pointing corrections were less than 1%. Data were calibrated against Hydra A (3C218) on the flux scale of Ott et al. 1994.

The flux densities were: 1.5 Jy at 2.28 GHz, 1.4 Jy at 4.8 GHz, 1.75 Jy at 8.4 GHz and 1.8 Jy at 12.2 GHz. Bandwidths were 32MHz at 2.28 GHz, 400 MHz at 4.8 GHz and 8.4 GHz, and 170 MHz at 12.2 GHz. One sigma uncertainties were estimated to be +-0.1, 0.05, 0.05 and 0.15 Jy in the respective bands.

The Australia Telescope Compact Array (ATCA) was used to make "snapshot" observations of PKS 0454-234 at frequencies between 5.5 and 35 GHz on 25 October 2011. Data at all frequencies was collected between 1200 and 1320 UTC, and calibrated against the ATCA primary flux calibrator PKS 1934-638.

The flux densities are: 1.6 Jy at 5.5 GHz, 1.8 Jy at 9 GHz, 2.1 Jy at 17 GHz, 2.1 Jy at 19 GHz, 1.9 Jy at 33 GHz, 1.9 Jy at 35 GHz (where each flux density has a one-sigma uncertainty of +- 0.1 Jy). Each frequency is the centre of a 2 GHz wide band. Comparison with regular calibrator monitoring earlier this year indicates the flux density of PKS 0454-234 is currently 28% higher at 17/19 GHz than on May 3, and 23% higher at 33/35 GHz than on September 17.

Further monitoring will be continued with the ATCA and Hartebeesthoek telescopes and possible future activity will be reported using this platform.