Optical flare observed in the flaring gamma-ray FSRQ PMN J0231-4746
ATel #13248; Tapio Pursimo (NOT), Julia Martikainen (NOT), and Roopesh Ojha (NASA/GSFC/UMBC).
on 31 Oct 2019; 14:15 UT
Credential Certification: Roopesh Ojha (Roopesh.Ojha@gmail.com)
Subjects: Optical, Gamma Ray, >GeV, AGN, Blazar, Quasar
We report optical photometry of the FSRQ PMN J0231-4746, 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#13209). The source is also reported to be brighter by a factor of 4 in the 2-10keV band (Atel#13212).
These NOT observations were made using the ALFOSC (Alhambra Faint Object Spectrograph and Camera) instrument at the epoch 2019-10-30T00:42. Standard IRAF data reduction (de-biasing + flat field correction with twilight flats) was carried out and aperture photometry was performed. The brightness was calibrated against eight SDSS field stars within 3.3 arc min radius of the target. Magnitude zero points were estimated by using Gaia DR2 G, BP, and RP magnitudes and the photometric transformations from Gaia passbands to the SDSS system (http://gea.esac.esa.int/archive/documentation/GDR2/). The Gaia DR2 magnitude conversions have scatter 0.164, 0.067, and 0.099 for the SDSS g, r, and i bands respectively.
We find that PMN J0231-4746 had SDSS magnitudes (and corresponding zero-point standard deviation)::
| Filter |
SDSS mag |
Zero-point SD |
g |
17.600 |
0.039 |
| r |
17.297 |
0.019 |
| i |
17.112 |
0.047 |
This compares to Gaia magnitudes (using the same transformation as for above) of:
Gaia (SDSS g)= 18.167
Gaia (SDSS r)= 18.003
Gaia (SDSS i)= 17.972
This result suggests that there is significant enhancement in the optical brightness of the flaring gamma-ray FSRQ PMN J0231-4746.
We encourage further multi-wavelength coverage. We will continue to monitor this source and report future developments using this and other platforms.
