Multi-band radio emission enhancement of the flat spectrum radio quasar OP 313

ATel #17194; Yu. V. Sotnikova, T. V. Mufakharov, A. K. Erkenov, T. A. Semenova, R. Yu. Udovitskij (SAO RAS), Yu. A. Kovalev (ASC Lebedev), A. V. Popkov (MIPT, ASC Lebedev)
on 20 May 2025; 09:01 UT
Credential Certification: Timur Mufakharov (timur.mufakharov@gmail.com)

Tweet

The significant brightening of the flat spectrum radio quasar OP 313 (BZU J1310+3220, 4FGL J1310.5+3221) was recently been reported in gamma-ray (ATel #17167), near-infrared (ATel #17179) and optical bands (ATel #17173, #17184, #17185) over the past two weeks. This source is included in the RATAN-600 long-term monitoring program, and it has exhibited a consistent upward trend in radio flux density since January 2017 (see the light curves at 2.3, 4.7, 8.2, 11.2, 14.4, and 22.3 GHz at the link below).

On 2025 May 8, we measured its flux densities at five frequencies using the RATAN-600 telescope, obtaining the following values (in Jy):

• 4.37 ± 0.6 at 22.3 GHz
• 4.22 ± 0.4 at 14.4 GHz
• 3.93 ± 0.4 at 11.2 GHz
• 3.85 ± 0.3 at 8.2 GHz
• 2.71 ± 0.2 at 4.7 GHz

These measurements indicate that OP 313 is currently in its highest radio emission state observed over the past decade, based on our monitoring data.

The RATAN-600 light curves of OP 313