Optical flare observed in the flaring gamma-ray blazar Ton 599

ATel #10948; Tapio Pursimo (NOT), Ana Sagues (NOT), John Telting (NOT), and Roopesh Ojha (NASA/GSFC/UMBC)
on 11 Nov 2017; 00:49 UT
Credential Certification: Roopesh Ojha (Roopesh.Ojha@gmail.com)

Subjects: Optical, Gamma Ray, >GeV, AGN, Blazar, Quasar

We report optical photometry of the flat spectrum radio quasar Ton 599, obtained with the 2.56m Nordic Optical Telescope in La Palma, to look for any enhanced optical activity associated with a recent flare in the daily averaged gamma-ray flux (ATel#10931, ATel#10937).

These NOT observations were made using the ALFOSC (Andalucia Faint Object Spectrograph and Camera) instrument at the epoch 2017-11-10T06:08. Standard IRAF data reduction (de-biasing + flat field correction with twilight flats) was carried out and differential photometry was performed. The brightness was estimated against six SDSSr stars between 13.3 and 17.4 magnitude. The std-dev of the zero point was 0.07 mag.

We find that Ton 599 had an SDSS r-magnitude = 14.22+/-0.07 (AB-system). This result suggests that there is significant enhancement in its optical magnitude. For example, an historic value of this object's r-magnitude at epoch 2004.9514 is 18.096+-0.007 (Aladin/SDSS-DR9).

This object was also reported to be flaring in the optical/UV/X-ray (ATel#10938) and NIR (ATel#10932). We encourage further multi-wavelength coverage. We will continue to monitor this source and report future developments using this and other platforms.