The blazar S4 0954+658: fast flare up to year maxima
ATel #17080; V. V. Vlasyuk, O. I. Spiridonova (Special Astrophysical Observatory of the Rus. Ac. Sci.)
on 16 Mar 2025; 01:04 UT
Credential Certification: Alexander Moskvitin (mosk@sao.ru)
Subjects: Optical, Blazar
As it was noted in ATel #17005 the blazar S4 0954+658 demonstrated optical activity phase within last months, which accompanies activity in the gamma range (ATel #16994). According to our estimates its brightness did not exceed R = 14.4 mags at January. After smooth fading up to R = 15.5 mag (MJD 60744 and 60745) its brightness immediately returned to phase of brightening between March 10th and March 15th. Our last estimates gave the maximal brightness of the blazar as high as R = 14.10 +/- 0.01 (MJD 60749.9). The mean slope brightness growth is about 0.25 mags per day within last 5 days. The similar flux density was observed only at 2024 January (ATel #16491).
The monitoring of the S4 0954+658 is still in progress; the most of data were taken under good weather condition (seeing (FWHM) < 1.5 arcsec and normal transparency) and have typical accuracy about 0.02 mags, which is twice as high with respect of typical value due to bright Moon sky background. The calibration procedure was performed using standard stars, as proposed by Raiteri C. M. et al., 1999, A&A 352, 19.
We strongly encourage further multi-wavelength studies.
