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Optical, X-, HE Gamma-ray flare of the FSRQ Ton 599

ATel #10938; L. Pacciani (IAPS-INAF Italy), A. Stamerra (INAF-Italy & SNS Pisa Italy)
on 8 Nov 2017; 15:43 UT
Credential Certification: Luigi Pacciani (luigi.pacciani@iaps.inaf.it)

Subjects: Optical, Ultra-Violet, X-ray, Gamma Ray, >GeV, AGN, Black Hole, Blazar

Referred to by ATel #: 10948

On 2017-10-29 the FSRQ Ton 599 (z=0.72449), triggered our HE monitor of FERMI-LAT data at E > 10 GeV with TS ~86 (see, Pacciani et al. 2014, ApJ, 790, 45 for a description of the method). The source became very bright in nir (ATel #10932), and in gamma-ray during the last week (ATel #10931, #10937). We obtained 3 follow-up observations with Swift on 2017-10-30, 2017-11-01, 2017-11-03. Other 3 observations are scheduled. The Swift Follow-up revealed the source at its brightest level in optical and X-ray. The preliminary Swift-UVOT photometry on 2017-11-01 is:

V = 14.09 +- 0.02

B = 14.47 +- 0.02

U = 13.68 +- 0.02

UVW1 = 13.55 +- 0.02

UVM2 = 13.55 +- 0.02

UVW2 = 13.75 +- 0.02

which is >3 times brighter with respect to the previous optical peak flux on 2012-06-26 (swift obsid: 00036381017). Magnitudes are in Vega system and have not been corrected for Galactic extinction.

The simultaneous Swift-XRT observation gives a counting rate of 0.146+/-0.008 cps and an unabsorbed flux of (6.4+/-0.4)E-12 erg cm^-2 s^-1 in the 0.3-10 keV band, to be compared with a mean flux of (4.1+/-0.3)E-12 erg cm^-2 s^-1 on April-May 2014.

We thank the Swift team and Swift Observatory Duty Scientist for rapidly scheduling our observations.