SWIFT follow-up of the flaring blazar PKS0346-27 (BZQJ0348-2749)
ATel #12336; Roberto Nesci (INAF/IAPS-Roma), Roberto Angioni (MPIfR-Bonn), Sara Buson (NASA/GSFC-USRA), Justin Finke (U. S. Naval Research Laboratory, Washington DC)
on 28 Dec 2018; 19:02 UT
Credential Certification: Roberto Nesci (Roberto.Nesci@iaps.inaf.it)
Subjects: Infra-Red, Optical, Ultra-Violet, X-ray, AGN, Blazar, Quasar
Referred to by ATel #: 12479
We are monitoring PKS0346-27 since its Gamma-ray outburst in February 2018 (ATel #11251) with the REM telescope on La Silla (ATel #11269). After the NIR and optical brightening announced respectively by Carrasco et al. (ATel #12310) and Kumar et al. (ATel #12324) we obtained a 3061s ToO pointing by Swift-XRT and UVOT instruments on 2018-12-25.6; nearly simultaneous r,i,J,H data were collected by our REM monitoring. The source is also very bright in Gamma-ray since mid December (peaking around 1E-6 ph/s in the 100-300000 MeV range) from the public LAT-monitored sources (https://fermi.gsfc.nasa.gov/ssc/data/access/lat/msl_lc/source/PKS_0346-27) .
Swift data were analized with the tools available at the SSDC (www.ssdc.asi.it); REM data were measured with IRAF/APPHOT using 2MASS and UCAC4 nearby comparison stars. The X-ray flux was 0.111 +-0.007 c/s: the spectrum was well fitted by a power law with photon index -1.60 +-0.11 using 12 PHA bins with a reduced chi square 1.28. Photometry was available for all six UVOT filters (V,B,U,W1,M2,W2): V= 16.78 +-0.05; B=17.34 +-0.05; U=16.46 +-0.04; W1=16.40 +-0.05; M2=16.55 0.05; W2=16.71 0.04 .
REM images show the source at H=13.57 +-0.05, half-magnitude fainter than H=13.04 reported in ATel #12310 by Carrasco et al. on Dec 19; J=14.54 +-0.05; i=16.35 +-0.05; r=16.65 +-0.03. The optical-NIR spectrum, from the H to the W2 band, is well fitted by a power law with photon index -2.52 . Overall the spectral energy distribution (SED) is fully consistent with a Synchrotron emission for the NIR-optical and an Inverse Compton for the X-ray branch (see figure).