Optical, X-, Gamma-ray flare of the FSRQ PKS 2032+107

ATel #7588; Luigi Pacciani (INAF-IAPS)
on 4 Jun 2015; 11:00 UT
Credential Certification: Luigi Pacciani (luigi.pacciani@iaps.inaf.it)

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We detected a gamma-ray flare from the FSRQ PKS 2032+107 (z=0.601), triggering on FERMI-LAT data at E > 10 GeV with TS ~46, from 2015-05-23 to 2015-06-02, following the prescription of Pacciani et al. 2014, ApJ, 790, 45. The gamma-ray spectrum changed from flat at the beginning of activity phase, to soft. The gamma-ray flux, integrated for one day (starting from 2015-06-01 20:11:15) was (316+/-34)E-8 ph cm^-2 s^-1, photon index 2.30+/-0.19, TS ~ 196 (E>0.1 GeV). to be compared with the catalog flux of 4.2E-8 ph cm^-2 s^-1 reported in the 3rd Fermi-LAT point-source catalog. The FERMI-LAT revealed gamma-ray emission up to ~49 GeV during the flat phase, and up to 11 GeV during the soft and brighter phase.

The source has been detected in high gamma-ray state also on April 2015 (ATel#7453, ATel#7457).

The Swift Follow-up revealed the source in high state in optical and X-ray. The preliminary Swift-UVOT photometry on 2015-06-03 is:

V = 17.74 +/- 0.09

B = 18.70 +/- 0.08

U = 18.49 +/- 0.09

UVW1 = 19.2 +/- 0.1

UVM2 = 19.9 +/- 0.2

UVW2 = 20.4 +/- 0.2

The optical/uv flux was ~50% brighter at the beginning of Swift follow-up (on 2015-05-28).

Magnitudes are in the UVOT photometric system (Poole et al. 2008, MNRAS, 383, 627) and have not been corrected for Galactic extinction.

The simultaneous Swift-XRT observation gives a counting rate of 0.083+/-0.005 cps, a photon index 1.24+-0.18, an unabsorbed flux of (5.8+-0.5)E-12 erg/cm2/s which is ~3 times brighter than previpusly reported on 2015 April 28 (ATEL#7460). We encourage further multi-wavelength observations. We thank the Swift team and Swift Observatory Duty Scientist for rapidly scheduling our observations.