Optical Flare in the gamma-ray active FSRQ PKS 1335-127

ATel #13771; Tapio Pursimo (NOT), Julia Martikainen (NOT), and Roopesh Ojha (NASA/GSFC/UMBC)
on 1 Jun 2020; 02:24 UT
Credential Certification: Roopesh Ojha (Roopesh.Ojha@gmail.com)

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We report optical photometry of the FSRQ PKS 1335-127, obtained with the 2.56m Nordic Optical Telescope in La Palma, to look for any enhanced optical activity associated with its enhanced gamma-ray emission state (ATel#13741).

These NOT observations were made using the ALFOSC (Alhambra Faint Object Spectrograph and Camera) instrument. Standard IRAF data reduction (de-biasing + flat field correction with twilight flats) was carried out. The magnitude is obtained using SExtractor MAG_AUTO and the magnitude zero point was calibrated against PS1 field stars near the target. We estimate the zero point to be less than 0.1 mag.

We find that PKS 1335-137 had the SDSS magnitudes at epoch 2020-05-19T21:40:
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Filter   Magnitude   Mag_Error
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  g          16.750          0.007
  r          16.124          0.006
  i          15.713          0.005
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This compares to PS1 and SMSS (SkyMapper Southern Survey) magnitudes at epochs 2012-06-24 and 2014-05-24, respectively:
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Filter   PS1_mag   Mag_Error   SMSS_mag   Mag_Error
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g            18.695           0.05             17.83             0.218
r             17.593           0.29             17.53             0.262
i             17.576           0.01             17.36             0.367
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This result suggests that there is significant enhancement in the optical brightness of the flaring gamma-ray FSRQ PKS 1335-137, of about 1.5 to 2 magnitudes. In addition, see http://gsaweb.ast.cam.ac.uk/alerts/alert/Gaia19dmc/

We encourage further multi-wavelength coverage. We will continue to monitor this source and report future developments using this and other platforms.