Blazar S4 0954+65 : new absolute brightness maximum

ATel #15344; V. V. Vlasyuk, O. I. Spiridonova, A. S.Moskvitin, O. A.Maslennikova, (Special Astrophysical Observatory of the Rus. Ac. Sci.)
on 22 Apr 2022; 15:15 UT
Credential Certification: Alexander Moskvitin (mosk@sao.ru)

Tweet

Blazar S4 0954+65 is observing by SAO RAS team on a regular basis in search of possible correlation between its optical and radio activity events. Since January 2021 we have started intense optical observations with two SAO RAS telescopes: 1-m reflector Zeiss-1000 and 0.5-m RC500 reflector (JSC ASTROSIB, Russia).We have observed S4 0954+65 with RC500 telescope in BVR passbands practically every night with appropriate atmospheric conditions. The observations with Zeiss-1000 were less extensive and realized according to telescope's schedule. Typical accuracy of our data was about 0.01 mag. while object was brighter than 15 mag. in active phase under good transparency and seeing value (FWHM) between 2" and 3". We have got about 2000 and 330 independent measurements in R-band with RC500 and Zeiss-1000 telescopes, respectively.

As our data showed, the current activity phase of S4 0954+658 begun in last decade of February when it's R-magnitude exceeded 15 mag. and left at these levels up to second decade of April. Local maximum at this period was about 14.4 mag. at March, 23th.

The most prominent brightness flash for S4 0954+658 was started between April, 9th and April, 11th , when it increased by 1 magnitude (as was noted in ATel #15322). Our measurements gave some lower values --- R-mag reached only 13.8 mag. at MJD = 59680.85. The next local maximum at R = 13.58 mag. was reached at epoch MJD = 59685.05. The last (absolute from our own data) maximum (13.20 mag) was observed by us last night twice at MJD = 59690.74 (with Zeiss-1000) and at MJD = 59690.89 (with RC-500). Accuracy of our data may be estimated as high as 0.015--0.02 mag. mostly due to 3--4" seeing under windy weather. It is interesting, that flux of source demonstrated "V-shape" behaviour with amplitude 0.25 mag. between 17.5UT and 21.5UT. After last maximum the object became fainter by 0.25 mag. within 1 hour. The similar values for S4 0954+65 were detected earlier only at 2015 February, 11th (ATel #7057, ATel #7083).

We strongly encourage further multiwavelength coverage.