Optical/UV, High Energy Gamma-ray activity from the FSRQ PKS 1502+106

ATel #7783; Luigi Pacciani (INAF-IAPS)
on 10 Jul 2015; 15:57 UT
Credential Certification: Luigi Pacciani (luigi.pacciani@iaps.inaf.it)

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We asked a Swift ToO campaign on the FSRQ PKS 1502+106 (z=1.83853), triggered by prolonged High Energy activity detected with FERMI-LAT. The HE trigger detected activity at E > 10 GeV with TS ~153, from 2015-06-17 to 2015-07-10, following the prescription of Pacciani et al. 2014, ApJ, 790, 45. The flux integrated on the whole period is (96+-4)E^-8 ph cm^-2 s^-1 (E> 0.1 GeV). The gamma-ray flux, integrated for one day (starting from 2015-07-06 23:17:09) was (89+/-13)E-8 ph cm^-2 s^-1, photon index 1.82+/-0.14, TS ~ 268 (E>0.1 GeV). The FERMI-LAT revealed gamma-ray emission up to ~37 GeV.

The source has been already detected in high gamma-ray state from the end of may 2015 (ATel#7592).

The Swift Follow-up revealed the source in high state in optical/UV. The preliminary Swift-UVOT photometry on 2015-07-08 is:

V = 16.49 +/- 0.07

B = 16.88 +/- 0.05

U = 16.30 +/- 0.05

UVW1 = 16.59 +/- 0.06

UVM2 = 16.63 +/- 0.03

UVW2 = 16.84 +/- 0.05

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

The optical/uv flux level is comparable with the brightest uvot detected state for the source on 2008-08-08.

The simultaneous Swift-XRT observation gives a counting rate of 0.083+/-0.005 cps, a photon index 1.62+-0.25 (90% c.l.), an unabsorbed flux of (1.4-0.10+0.24)E-12 erg/cm2/s.

We encourage further multi-wavelength observations. We thank the Swift team and Swift Observatory Duty Scientist for rapidly scheduling our observations.