An exceptional optical flare of the flat spectrum radio quasar PKS B2258-022
ATel #16953; Simone Leonini, Massimo Conti, Paolo Rosi, Luz Marina Tinjaca Ramirez (Montarrenti Observatory, Sovicille (Siena - Italy)); Alessandro Marchini (Astronomical Observatory, University of Siena - Italy); Leonardo Stiaccini, Gaia Verna (Department of Physical Sciences, Earth and Environment (DSFTA), University of Siena - Italy); Giacomo Bonnoli (INAF - Brera Astronomical Observatory)
on 15 Dec 2024; 22:30 UT
Credential Certification: Giacomo Bonnoli (giacomo.bonnoli@inaf.it)
Subjects: Radio, Optical, X-ray, Gamma Ray, VHE, Request for Observations, AGN, Blazar, Transient
Right after local sunset, we observed the flat spectrum radio quasar PKS B2258-022 (R.A. = 345.28324 deg, Decl. = -1.96794 deg; J2000; Hunt et al. 2021, AJ, 162, 18) at redshift z=0.777 (Albareti et al. 2017, ApJS, 233, 25) from the Montarrenti Astronomical Observatory (IAU MPC observatory code C88) located near Sovicille (Siena, Italy). This observation was triggered by the publicly available Fermi-LAT Monitor GCN Notice #1734278317 reporting an intense gamma-ray flare from the source. The alert was soon followed by ATel#16952 posted on behalf of the Fermi/LAT Collaboration, confirming that on Dec. 14,2024 the highest gamma-ray daily flux ever observed by LAT for this source was measured.
On 2024 Dec. 15.75 we detected a remarkable optical flare at R=14.48(0.01) in the Johnson-Cousins photometric system. Quoted uncertainty is statistical only. The magnitude determination has to be considered preliminary, and prone to further refinements. Reference and check stars in the field of view were selected from the APASS9 (Henden et al., 2016) catalogue. The reference R magnitudes were derived from those reported in the same APASS9 catalogue after conversion between the two different photometric systems, following a formula from Munari U., "Classical and Recurrent Novae", JAAVSO, 40 (2012). The comparison with the V-band publicly available light curve extracted from the ASAS-SN sky patrol database at http://asas-sn.ifa.hawaii.edu/skypatrol/objects/661425999919 puts this R-band measurement at the highest flux levels along the last decade at least, if we assume a tentative V-R colour around 1.
Any enquiry on these observations can be addressed either to Simone Leonini (s.leonini@iol.it) or to Giacomo Bonnoli (giacomo.bonnoli@inaf.it). We will continue monitoring the source in the following nights. Multi-wavelength follow-up is encouraged.
The Montarrenti Astronomical Observatory carries on its research programs with a 0.53 m f/8.7 Ritchey-Chretien telescope equipped with an Apogee Alta U47 CCD camera. More information on the Montarrenti Astronomical Observatory can be found on the official webpage of the Unione Astrofili Senesi.
Official website of the Unione Astrofili Senesi
