The Blazar 1ES 1959+650 in a new phase of activity

ATel #16186; O. Domann, N. Bader, N. Boutter, M. Brown, S. Dürr, L. S. Girschick, R. Goldbach, F. Hemrich, B. Horst, S. Hüsam, O. Koppitz, G. Manhalter, F. Molz, L. Raaber, M. Rauschert, F. Reuther, D. Schneider, R. Steineke, K. Wachsmuth, M. Feige, D. Reinhart, N. Zottmann, C. Lorey (all Hans-Haffner-Sternwarte – Friedrich-Koenig-Gymnasium Wuerzburg) K. Mannheim (Universitaet Wuerzburg), D. Elsaesser (TU Dortmund)
on 13 Aug 2023; 18:46 UT
Credential Certification: Dominik Elsaesser (dominik.elsaesser@tu-dortmund.de)

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The AGN 1ES 1959+650 (RA: 19 59 59.8520 Dec: +65 08 54.6525; ICRS J2000; z=0.048) reached a magnitude of 13.535 in the R-band during the last nights. Thus this BL Lac object displayed one of the brightest magnitudes of the last ten years. In that rough time frame, only during the major flares in late 2016 and late 2017 the object was slightly brighter (13.501 mag and 13.437 mag, all R-band).
As described in ATel # 16083, the brightness of this object steadily increased from slightly below 14.5 mag (R-band) since April of the present year to 13.80 mag in mid-June. After that the object dimmed again slightly by about 0.1 mag until from the end of June it slowly became brighter again until mid-July. After a further small decrease, the brightness increased by 0.25 mag since beginning of August.
The optical high state reported here seems to correspond well with the 0.3-10 keV observation performed with the X-ray Telescope onboard the Neil Gehrels Swift Observation (Swift-XRT), which was reported in ATel # 16087 and ATel # 16162. Here, approximately a doubling of the flux was reported from the beginning of February to a strong X-ray flaring state corresponding to 13.25+/-0.14 cts/s in mid-June. During the same period, we measured an increase in optical brightness of about 0.6 mag (R band). Also the reported further course of the X-ray activity with a slight up and down and exceptionally high values at least quantitatively corresponds quite well with the course of the optical brightness in the R-band.

We report the following preliminary R-band magnitudes that continue the values from ATel # 16083:

JD 2460109.4003: 13.759 (0.005)
JD 2460109.5401: 13.757 (0.004)

JD 2460110.3860: 13.718 (0.006)
JD 2460110.4148: 13.730 (0.004)

JD 2460111.4560: 13.775 (0.005)
JD 2460111.5584: 13.770 (0.005)

JD 2460112.3739: 13.721 (0.008)
JD 2460112.5789: 13.754 (0.008)

JD 2460113.4488: 13.799 (0.005)
JD 2460113.4997: 13.799 (0.005)

JD 2460116.5199: 13.818 (0.007)
JD 2460117.5442: 13.849 (0.008)

JD 2460119.4028: 13.808 (0.005)
JD 2460119.5430: 13.837 (0.005)

JD 2460120.4585: 13.862 (0.005)
JD 2460124.5748: 13.857 (0.007)
JD 2460126.3791: 13.857 (0.018)
JD 2460131.5132: 13.740 (0.006)
JD 2460133.5751: 13.740 (0.016)
JD 2460134.4256: 13.694 (0.004)
JD 2460140.4231: 13.697 (0.013)
JD 2460148.4364: 13.786 (0.005)
JD 2460154.5601: 13.789 (0.004)
JD 2460164.3409: 13.580 (0.006)
JD 2460166.4973: 13.609 (0.004)

JD 2460167.3263: 13.587 (0.009)
JD 2460167.4374: 13.581 (0.003)

JD 2460168.3346: 13.535 (0.004)

JD 2460169.4012: 13.555 (0.004)
JD 2460169.4539: 13.559 (0.004)
JD 2460169.5487: 13.602 (0.006)

As already suspected in November 2022 (ATel # 15778) and June 2023 (ATel # 16083), 1ES 1959 may have entered a new phase of exceptional activity, which is why we encourage further multiwavelength measurements of this object.


These measurements reported here 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 the TU Dortmund with the 0.5m CDK-astrograph by using Besselfilters at the school and university observatory Hans-Haffner-Sternwarte in D-97265 Hettstadt (Germany).

Naturwissenschaftliches Labor fuer Schueler am Friedrich-Koenig-Gymnasium (FKG)