The blazar S5 1044+71 shows exceptionally high optical activity

ATel #17999; S. Duerr, L. Lehmann, B. Lehmann, O. Domann, E. Bommert, M. Heemskerk, F. Lach, F. Pfeuffer, H. Reinhart, R. Reinhart, M. Feige, D. Reinhart, R. Steineke, N. Zottmann, C. Lorey (all Hans-Haffner-Sternwarte, Friedrich-Koenig-Gymnasium, Wuerzburg, Germany) K. Mannheim (University of Wurzburg, Germany) D. Elsaesser (TU Dortmund, Germany)
on 23 Aug 2026; 13:44 UT
Credential Certification: Dominik Elsaesser (dominik.elsaesser@tu-dortmund.de)

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The flat-spectrum radio quasar S5 1044+71 (also known as 6C 104451+715930) at R.A. = 10 48 27.6199 and Dec. = +71 43 35.9384 in the ICRS (J2000) coordinate system; z = 1.150 (data from the Simbad Astronomical Database) reached a notably high brightness two nights ago with an optical magnitude of 15.882 ± 0.012 in the R band.

Over the past four months, the brightness of this AGN has fluctuated roughly between 17.5 and 16.5 mag in the R band, with minor variations above and below this range. Over the past two months, it has remained above 16.9 mag.
In early March of this year, a flare from this object was reported, during which it reached an optical magnitude of 16.25 ± 0.01 in the R band (ATel #17715).
The observations were carried out as part of the WEBT collaboration (https://www.oato.inaf.it/blazars/webt).

We report the following preliminary R-band magnitudes:

JD 2461255.4931: 16.817 ± 0.046
JD 2461260.4844: 16.768 ± 0.019
JD 2461261.4946: 16.737 ± 0.017
JD 2461262.5040: 16.613 ± 0.018
JD 2461263.4199: 16.412 ± 0.013
JD 2461267.4301: 16.169 ± 0.010
JD 2461273.5512: 15.882 ± 0.012
JD 2461275.3223: 16.460 ± 0.031
JD 2461275.4319: 16.430 ± 0.013

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.
Comparison stars and their magnitudes were taken from the Gaia DR3 catalog and converted to the Johnson-Cousins system using the factors specified there.
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