Swift detections of the flaring blazar GAIA 18ayp (PKS 2333-415) in X-rays and the UV

ATel #11580; Dirk Grupe (Morehead State University), S. Komossa (MPIfR), R. Angioni (MPIfR, Univ. Wuerzburg), N. Schartel (ESA - ESAC)
on 26 Apr 2018; 22:14 UT
Credential Certification: Dirk Grupe (dgrupe007@gmail.com)

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We report Swift observations of the z=1.41 QSO GAIA 18ayp (PKS 2333-415) which was detected by GAIA in an optically flaring state on 2018-April-14. Swift observed GAIA 18ayp on 2018 April 23 for a total of 1.4 ks. The QSO is clearly detected in X-rays and the UV. The X-ray position found using the enhanced XRT position (Goad et al. 2007, Evans et al. 2009) is RA-2000 = 23 36 34.1, Dec-2000 = -41 15 21.4 with an uncertainty of 3.0". This position coincides with the z=1.41 blazar PKS 2333-415. The X-ray spectrum in the observed 0.3-10 keV band can be fitted with an absorbed power law model with the absorption column density fixed to the Galactic value (1.71e20 cm^-2). The X-ray photon index is Gamma = 1.65+/-0.43. The flux in the observed 0.3-10 keV band is (1.2+/-0.2)e-15 W m^-2. In the UVOT, the QSO was observed in the W1 and M2 filters with 17.65+/-0.10 and 18.27+/-0.07 mag in the Vega system, respectively (not corrected for Galactic extinction). In the 0.1-300 GeV gamma-ray band, the blazar is associated to the Fermi-LAT catalog source 3FGL J2336.5-4116 (Acero et al. 2015, ApJS, 218, 23). No significant gamma-ray emission positionally consistent with this source was detected by the LAT on the time scales corresponding to the optical and X-ray observations reported above, showing that there is no gamma-ray flaring activity corresponding to the multi-wavelength variability. We derive an upper limit on the gamma-ray flux (E>100 MeV) in the time period 14-23 April 2018 of 8.0 x 10^-8 photons cm^-2 s^-1.