Optical follow-up of S5 0532+82
ATel #16122; Stefano Valentini (MPC 589), Antonio Vagnozzi (MPC 589), Roberto Nesci(INAF/IAPS)
on 8 Jul 2023; 08:35 UT
Credential Certification: Roberto Nesci (roberto.nesci@inaf.it)
Subjects: Optical, AGN, Blazar, Quasar
Following the announcement of a strong Gamma ray flare of 4FGL J0543.2+8238, in ATel #16117, we observed the source with the 30cm reflector of the Observatory S.Lucia di Stroncone (MPC 589) using a SBIG STL-1001E camera without filter, on 2023-07-06 and 2023-07-07. Bad weather prevented observations in the previous days, nearer to the flare which happened on 2023-06-30.
Comparisons stars were taken from the Gaia DR3 catalog using the G magnitudes: aperture photometry was performed with IRAF/apphot. A linear fit of the instrumental vs catalog magnitudes gave a very good result with rms deviation 0.04 mag and slope 1.03 down to G=19.3.
4FGL J0543.2+8238 was not detected, so we put an upper limit at G=19.5. The quiescent level of the source in Gaia DR3 is G=20.85
The Gamma ray flare was about 200 times brighter than the normal level: if optical and Gamma-ray flares are strongly coupled, as is the case in several Blazars (see e.g. Nesci et al. 2021 MNRAS 502 6177) it should imply a several magnitude increase in the optical, which we did not see.
