The flaring flat spectrum radio quasar OP 313 shows another remarkable rising trend in the optical band
ATel #16964; Alessandro Marchini (Astronomical Observatory, University of Siena - Italy); Leonardo Stiaccini, Gaia Verna (Department of Physical Sciences, Earth and Environment (DSFTA), University of Siena - Italy); Simone Leonini, Massimo Conti, Paolo Rosi, Luz Marina Tinjaca Ramirez (Montarrenti Observatory, Sovicille (Siena - Italy)); Giacomo Bonnoli (INAF - Brera Astronomical Observatory)
on 1 Jan 2025; 00:01 UT
Credential Certification: Giacomo Bonnoli (giacomo.bonnoli@inaf.it)
Subjects: Radio, Optical, X-ray, Gamma Ray, VHE, Request for Observations, AGN, Blazar, Transient
We are densely monitoring the flat spectrum radio quasar OP 313 (R.A. = 197.619 deg, Decl. = +32.345 deg; J2000; Johnston et al. 1995, AJ, 110, 880) at redshift z=0.997 (Schneider et al. 2010, AJ, 139, 2360) in the optical band, both from the Astronomical Observatory of the University of Siena (IAU MPC observatory code K54) and the Montarrenti Astronomical Observatory (Sovicille, Siena, code C88). This effort is motivated by the clear signatures of intense emission in the optical (ATel#16891,#16951 and also ATel#16963 few minutes ago) and in gamma rays (see ATe#16940 and the publicly available Fermi-LAT Monitor GCN Notices #1730300179 #1734018885 and #1730386494) observed along the last two months.
The following table reports our latest measurements in the Johnson-Cousins photometric system. Quoted uncertainty is statistical only.
Civil Date(UT) Mag (dMag) Filter - Observatory
2024 Dec. 21.197 14.63 (0.02) R - Siena
2024 Dec. 22.198 14.50 (0.02) R - Siena
2024 Dec. 26.135 14.04 (0.01) R - Siena
2024 Dec. 27.138 13.91 (0.01) R - Siena
2024 Dec. 28.226 13.63 (0.01) R - Siena
2024 Dec. 29.208 13.43 (0.01) R - Siena
2024 Dec. 30.153 13.55 (0.01) R - Siena
2024 Dec. 30.157 13.57 (0.01) R - Montarrenti
2024 Dec. 31.164 13.34 (0.01) R - Siena
2024 Dec. 31.163 13.34 (0.01) R - Montarrenti
2024 Dec. 30.155 14.42 (0.01) B - Montarrenti
2024 Dec. 31.161 14.21 (0.02) B - Montarrenti
2024 Dec. 30.144 13.92 (0.01) V - Siena
2024 Dec. 30.156 13.93 (0.01) V - Montarrenti
2024 Dec. 31.163 13.71 (0.02) V - Montarrenti
2024 Dec. 30.157 13.05 (0.01) I - Montarrenti
2024 Dec. 31.164 12.83 (0.01) I - Montarrenti
After a new dimming of the flux following the peak at R=13.70(0.01) reported on 2024 Dec. 12.18 (ATel#16951) a systematic rising trend is evident since 2024 Dec. 21.187 when the source was found at R=14.63(0.02), with the brightest observed magnitude measured last night at R=13.34(0.01). This value represents the observed maximum in the optical R band along these last two months of intense activity, as well as a rather exceptional value along the decadal history of the source; furthermore, OP 313 is getting interestingly close to its known absolute records, observed in 2022, July 1.98 and 4.80 at values around R=12.6 (ATel#15496,#15515,#16360). The indication we derive is that the source keeps on undergoing a rather uncommon state of activity, deserving adequate attention.
A publicly available plot of the OP 313 data we collected in the last two months is linked at the end of this ATel, while more data and information are displayed at this webpage.
Any enquiry on these observations can be addressed either to Alessandro Marchini (marchini@unisi.it) or to Giacomo Bonnoli (giacomo.bonnoli@inaf.it). We will continue monitoring the source in the following nights. Multi-wavelength follow-up is strongly encouraged.
Brief descriptions of the instrumental setups used for the reported observations are available at the official webpage of the Astronomical Observatory of the University of Siena and on the website of the Unione Astrofili Senesi.
We take the opportunity of the New Yearâs Day to wish you all a happy 2025 full of amazing discoveries, and to share our hope that the astronomical community will keep on giving the whole world the good example of cooperation, respect and friendship we all deserve to develop a better one, concerned with peace and brotherhood.
Plot of the OP 313 observations from the Astronomical Observatory of the University of Siena and the Montarrenti Astronomical Observatory during the last two months of 2024
