CTA 102 shows strongly increasing optical activity again after quiet years
ATel #17200; C. Lorey, S. Duerr, O. Koppitz, N. Bader, N. Boutter, M. Feige, M. Heemskerk, T. Kaplan, F. Lach, L. Lehmann, G. Rinke, D. Paulini, D. Reinhart, D. Schneider, K. Schoch, J. Seufert, R. Steineke, N. Zottmann (all Hans-Haffner-Sternwarte, Friedrich-Koenig-Gymnasium, Wuerzburg, Germany) K. Mannheim (University of Wurzburg, Germany) D. Elsaesser (TU Dortmund, Germany)
on 22 May 2025; 06:35 UT
Credential Certification: Dominik Elsaesser (dominik.elsaesser@tu-dortmund.de)
The blazar CTA 102, also known as 4C 11.69 or PKS 2230+11, with ICRS coordinates (ep=J2000) RA 22h 32m 36.4089 and Dec +11d 43m 50.90406s and a redshift of z=1.0362 (all data from the astronomical database SIMBAD: http://simbad.u-strasbg.fr/simbad/ ) shows an exceptionally strong increase in optical brightness to a seven-year high in the last few nights.
While this object usually displays a brightness of 16 to 17 magnitudes in the R-band, its R-band brightness recently has increased from 16.7 to 13.8 mag.
One of the most impressive events regarding this source was the outburst at the end of 2016 to the beginning of 2017. Across the multi-wavelength range, the object reached unexpected brightness levels, in the optical range, for example, values brighter than 11.5 mag in the R band (see ATel # 9868 with R= 11.32 JD 2457738.33). Numerous Astronomers Telegrams report on observations over a span of about three months.
Also in the middle and end of 2017 (ATel # 10292; ATel # 10330; ATel # 10386, ATel # 10560; ATel # 11045; ATel # 11081) and in August 2019 (ATel # 13051; ATel # 13054; ATel # 13056) CTA 102 showed remarkable activity, each detected in different wavebands.
Since then, this object remained very quiet until three weeks ago. Since then, its brightness in the R band has increased by 2.8 magnitudes within 19 days.
We report the following preliminary R-band magnitudes:
JD 2460645.3626 16.066 ± 0.015
JD 2460665.2974 16.336 ± 0.019
JD 2460671.2623 16.133 ± 0.013
JD 2460672.2847 16.022 ± 0.027
JD 2460688.2320 15.507 ± 0.014
JD 2460692.2550 15.824 ± 0.013
JD 2460695.2573 16.155 ± 0.019
JD 2460709.2338 16.700 ± 0.060
JD 2460724.2471 16.272 ± 0.112
JD 2460797.5887 16.671 ± 0.055
JD 2460807.5548 15.648 ± 0.027
JD 2460809.5502 14.890 ± 0.021
JD 2460815.5646 14.655 ± 0.011
JD 2460815.5736 14.635 ± 0.010
JD 2460816.5703 13.838 ± 0.012
The observations were carried out as part of the WEBT collaboration (https://www.oato.inaf.it/blazars/webt). The WEBT photometric sequence for this source can be found at: https://www.oato.inaf.it/blazars/webt/2230114-cta-102/
Our measurements are carried out as part of the long-term AGN monitoring program of the Naturwissenschaftliches Labor fuer Schueler am Friedrich-Koenig-Gymnasium (FKG), the Universitaet Wuerzburg, and TU Dortmund University.
The optical data were acquired through a Bessel R filter (Chroma) with a 0.5m CDK-astrograph (PlaneWave) and a Moravian C4-16000EC camera at the school and university observatory Hans-Haffner-Sternwarte in 97265 Hettstadt, Germany (https://schuelerlabor-wuerzburg.de/en/observatory/).
Hans-Haffner-Sternwarte
