The blazar 3C345 - the highest brightness over almost two decades
ATel #17134; V. V. Vlasyuk, O. I. Spiridonova, A. S. Moskvitin and T. A. Fatkhullin (Special Astrophysical Observatory of the Rus. Ac. Sci.)
on 6 Apr 2025; 08:06 UT
Credential Certification: Alexander Moskvitin (mosk@sao.ru)
Subjects: Optical, Blazar
Our BVRI-monitoring of the bright blazars sample using our 1-meter and 0.5-meter reflectors is in progress. As it was noted in March (ATels #17059 and #17085), the blazar 3C345 is undergoing an epoch of exceptionally high optical activity. The last estimates of its brightness were performed with 1-meter reflector only with different photometers, which are equipped by conventional CCD and EM CCD detectors.
After achieving R = 15.83 mag at MJD 60738.12 the blazar became fainter by 1 magnitude within one week (R = 16.76 mag at MJD 60744.07) according to our estimates. The current most powerful re-brightening phase for 3C 345 started in the middle of March --- from level R=16.29 mag on March 14/15 night.
Now the 3C 345 is undergoing a phase of exponential growth with a slope between 0.15 and 0.2 mags per day. The highest level R=14.99 mag was detected within our last night observations (MJD 60770.94). We have detected the higher blazar brightness (R between 14.45 and 14.70) as far as 19 years ago --- within the course of its 2006 June-August outburst.
The monitoring of 3C 345 is continuing; the most of data presented were taken under good weather conditions (seeing (FWHM) < 2 arcsec and normal transparency) and have typical accuracy about 0.01 mags. We strongly encourage further multi-wavelength studies.
