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THE ASTRONOMER Electronic Circular No 3706      2022 May 17 10.20UT
Ed:Guy M Hurst, 16,Westminster Close, Kempshott Rise,  Basingstoke,
Hants, RG22 4PP,England.Telephone/FAX(01256)471074Int:+441256471074
INTERNET: GUY@TAHQ.ORG.UK             Backup: guy_hurst@hotmail.com
WORLD WIDE WEB                         http://www.theastronomer.org
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BLAZAR S4 0954+65 

Alessandro Marchini (Astronomical Observatory, University of Siena, Italy)
et.al. reports ATEL 15380. 

The BL Lac type object S4 0954+65
(RA: 09 58 47.2452 Dec: +65 33 54.8194; J2000)
has been showing strong activity in both the optical (ATel #15322; and
gamma-ray  bands in recent weeks. 

Some groups of the Whole Earth Blazar Telescope (WEBT) have been more
closely monitoring this object's enhanced activity during the last month
since the reports in April that it was particularly bright.
They observed the most extraordinary variations in optical brightness in the
R band during the four day interval 2022 May 11-14. Both the large amplitude
and the short time scale of brightness fluctuations are remarkable.
The data show several instances of drastic increase or drop in brightness of
almost one magnitude in less than two hours. At the extremes, increases and
decreases in brightness of almost half a magnitude occurred within about 15
to 30 minutes. During this interval, a new maximum brightness of R=12.72
(0.02) was observed on May 13 around 04:30 UT (JD 2459712.6873).

Although S4 0954+65 has historically shown a large variability in brightness
of 3 magnitudes or more in some cases, these changes normally occur within a
few weeks. The variability in brightness observed by us in the last few days
in such short time intervals is unusual for such an object, especially
because it has occurred several times in the last few days. 

The observations were conducted with a 0.3 m telescope at the Astronomical
Observatory of the University of Siena with a 0.4 m telescope at the Foggy
Bottom Observatory and with a 0.5 m telescope at the Hans-Haffner
Observatory
All data was acquired with a Rc standard filter and using the photometric
sequence for this source made available by the WEBT Collaboration 

We point out that on May 12-13, the Siena and Colgate Universities data
cover 13 continuous hours, when the maximum brightness of S4 0954+65 was
recorded. Therefore, we strongly encourage further multi-wavelength
coverage, especially from different longitudes. 

Guy m Hurst

