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To: stefano@bicar.it
From: atel@astronomerstelegram.org
Subject: ATel 17644, 17645
Message-Id: <20260204071102.3606228808F3@server.astronomerstelegram.org>
Date: Wed, 4 Feb 2026 02:11:02 -0500 (EST)

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Posted: Within the last 24 hours
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ATEL #17644							     ATEL #17644

Title:	Superflaring region AR14366: observing  opportunities
Author:	Costantino Sigismondi (ICRANet Pescara and APRA-ISF Rome,
		Italy), Adam J. Finley (ESA-ESTEC, The Netherlands), Virginio Oldani
		(Stazione Astronomica di Sozzago, IT), Paolo Ochner (UniPD and INAF-OAPd,
		IT).
Queries:	sigismondi@icra.it
Posted:	3 Feb 2026; 18:42 UT
Subjects:Radio, Optical, Ultra-Violet, X-ray, The Sun

There is the opportunity to observe the superflaring region AR14366, active
on the Earthside solar surface, spread around the Carrington Longitude
(C.L.) 197 degrees at Northern solar latitude 14 deg., with sunspots nested
around more than 20 degrees as on 3 February 2026 UT day. This region will
be visible from the Earth, until 9 February 2026.

AR 14366 is a rapidly growing region already larger than 1200 MH, with
strong magnetic activity, capable of dozens of M and some X-class flares
in the first two days of February 2026. It exhibits also a rythmic flaring
activity with main frequency around 7 hours.

It will enter indeed in the scientific literature in the next years.

AR 14366 can be considered, in the asymmetric hemispheric activity, as
the Northern response to the 2024 solar activity maximum, dominated by
Southern hemisphere's groups.

For reference, the AR 14274 on 11 November 2025 was spread 20 degrees around
the C. L. 269 deg., always on the Northern solar hemisphere at 24 deg.
North, while the AR 13664 and 13697 were spread 20 degrees around the C.
L. 340 deg. at 19 deg. South of the solar equator. There is lack of previous
activity in the 197 deg. C.L. region, where AR 14366 is appeared.

The organization -best within 10 February- of solar observations with H-alpha
and white light telescopes could attract, for the opportunity to see in
person these phenomena, potential future solar astronomers to this discipline.

It is reliable to expect a persistence of this giant sunspots' group also
for the next solar rotation in March 2026, as it was for the aforementioned
groups in May-June 2024 and November-December 2025.

Both the high rate of powerful flares and the high level of X-rays background
(several hours beyond M-level), have to be considered rare out of these
days.

Super flaring region AR 14366 : https://drive.google.com/file/d/1P6-MQNSeYbo3Aw82B61OlfjuCSVQi08H/view?usp=sharing
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Password Certification: Costantino Sigismondi (sigismondi@icra.it)
https://www.astronomerstelegram.org/?read=17644
==============================================================================
ATEL #17645							     ATEL #17645

Title:	SRG/ART-XC captures 3C 138 in a bright X-ray state
Author:	G. Uskov (1), S. Sazonov (1), I. Lapshov (1), A. Tkachenko
		(1), A. Lutovinov (1), A. G. Mikhailov (2), Yu. V. Sotnikova (2),
		T. V. Mufakharov (2, 3) (1 - Space Research Institute of RAS, Russia,
		2 - Special Astrophysical Observatory of RAS, Russia, 3 - Xinjiang
		Astronomical Observatory, China)
Queries:	sazonov@cosmos.ru
Posted:	3 Feb 2026; 19:02 UT
Subjects:X-ray, AGN, Quasar

Following the increased activity of the compact steep-spectrum quasar 3C&nbsp;138
in the radio, optical and gamma-ray bands over the recent months (ATels
#17539, #17540, #17461), we conducted a pointed X-ray observation of this
object with the Mikhail Pavlinsky ART-XC telescope on board the SRG observatory
on 28-29 January, 2026, with a total duration of 23.3 hours.

The spectrum measured in the 4&ndash;30 keV energy band can be approximated
by a power law with a photon index of 1.58 &plusmn; 0.08 modified by the
Galactic absorption (NH = 2.0 &times; 1021 cm&minus;2).
The unabsorbed flux in the observed 
4&ndash;20 keV energy band is (7.8 &plusmn; 0.2) &times; 10&minus;12&nbsp;erg&nbsp;s&minus;1&nbsp;cm&minus;2
(all quoted uncertainties are at the 90% level). 
This is a factor of 2&ndash;3 higher than during the Swift/XRT observations
performed at the end of March, 2025 (ATel #17142). We do not detect any
short-term variability during the ART-XC observation.

The ART-XC team plans to continue observations of 3C&nbsp;138 in the coming
months.

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Password Certification: Sergey Sazonov (sazonov@iki.rssi.ru)
https://www.astronomerstelegram.org/?read=17645
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