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To: stefano@bicar.it
From: atel@astronomerstelegram.org
Subject: ATel  17851, 17852, 17853
Message-Id: <20260622070757.28D1B28808BB@server.astronomerstelegram.org>
Date: Mon, 22 Jun 2026 03:07:57 -0400 (EDT)

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Posted: Within the last 24 hours
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ATEL #17851							     ATEL #17851

Title:	The predominant solar active region AR 4473 in action
Author:	Costantino Sigismondi (ICRANet Pescara and UPRA-SFI Roma,
		Italy)
Queries:	sigismondi@icra.it
Posted:	21 Jun 2026; 12:41 UT
Subjects:Radio, Optical, X-ray, The Sun

The solar activity in the last 5 months has been characterized by the apparition
of some "predominant active regions", capable of releasing a sequence of
relatively intense and frequent flares (e.g. AR 4366 at the beginning of
February 2026 [ATel#17644], AR 4420 at end April 2026 and AR 4455 at the
beginning of June 2026). The duration of these intense activities resulted
limited to three days. Within this time interval almost all solar flares
in the Earthside hemisphere are produced by the predominant region. Some
of the flares can be as intense as X-class. AR 4473, started to flare on
20 June 2026 at the Eastern solar limb, it is one of these predominant
regions. 
Its solar activity peaked already with M1 and M2.7 flares, and it can produce
more strong flares nearly each 12 hours, as suggested by the GOES X-ray
flux analysis.

The first day of activity of AR4473 (composite, souorce GOES/NOAA and LMSAL):
https://www.astronomerstelegram.org/?printform#link
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Password Certification: Costantino Sigismondi (sigismondi@icra.it)
https://www.astronomerstelegram.org/?read=17851
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ATEL #17852							     ATEL #17852

Title:	Major Solar Flare from AR 4473: does it peak its activity?
Author:	Costantino Sigismondi (ICRANet, Pescara and UPRA-ISF, Roma)
Queries:	sigismondi@icra.it
Posted:	21 Jun 2026; 22:30 UT
Subjects:Radio, Optical, Ultra-Violet, X-ray, The Sun

The predominant region AR 4473 (see ATel #17851) just released a major
flare peaked at M6.9 at 19:29 UT of 21 June 2026. 
It may be the last significant flare of the series, if the AR4473 region
behaves like the other predominant active regions mentioned in the previous
ATel#17851, where the prediction of this flare was published. 
Then the three days of intense activity would result a characteristic of
the descending phase, after the solar maximum, of the present solar cycle
no. XXV (2019-2030). 
Further observations will permit to include this region among the rapid
predominant regions (three days duration) or the superflaring regions (more
intense flares, lasting up to two or three solar rotations, as the AR 3664-AR
3697 of May-June 2024, or the AR 4366 of February 2026, see also ATel#17644).

The activity of the AR 4473 started on 19 June 2026, until 21 June it is
reported in the following link (pdf); its predominance during this period
of time is evident.

The activity of the solar AR 4473 (19-21 June 2026): https://drive.google.com/file/d/1fZsnZU_WWZuxPuTlb41kGpe_G3R-diXQ/view?usp=sharing
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Password Certification: Costantino Sigismondi (sigismondi@icra.it)
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ATEL #17853							     ATEL #17853

Title:	MAXI/GSC detection of a renewed activity from the Be/X-ray
		binary pulsar 1A 1118-616 or a possible new X-ray transient MAXI J1122-616
Author:	M. Nakajima, H. Negoro (Nihon U.), T. Mihara (RIKEN), K. Saito,
		T. Yokoyama, M. Wada (Nihon U.), T. Tamagawa, N. Kawai, M. Matsuoka
		(RIKEN), T. Sakamoto, M. Serino, S. Sugita, Y. Kawakubo, H. Hiramatsu,
		A. Yoshida (AGU), Y. Tsuboi, Y. Ishihara, H. Ogaki (Chuo U.), M. Shidatsu,
		C. Kang, M. Uenishi, T. Usuki, S. Yatsuzuka, H. Aoe (Ehime U.), I.
		Takahashi, Y. Yatsu (Science Tokyo), S. Nakahira, S. Ueno, H. Tomida,
		M. Kurihara (JAXA), Y. Ueda, K. Fujiwara, S. Kobayashi (Kyoto U.),
		M. Yamauchi, M. Nishio, C. Hiraizumi (Miyazaki U.), K. Yamaoka (Nagoya
		U.), M. Sugizaki (Kanazawa U.), W. Iwakiri (Chiba U.), T. Kawamuro
		(Osaka U.), S. Yamada (Tohoku U), S. Ogawa (TUS)
Queries:	nakajima.motoki@nihon-u.ac.jp
Posted:	22 Jun 2026; 06:49 UT
Subjects:Binary, Neutron Star, Transient, Pulsar

The MAXI/GSC nova alert system triggered on a weak X-ray enhancement from
the vicinity of the Be/X-ray binary pulsar 1A 1118-61 on 2026 June 17.
Assuming that the source flux was constant over the 26 scan transits between
21:28 UT on 2026 June 18 (MJD 61209) and 16:52 UT on 2026 June 20 (MJD
61211), we obtain the source position at

(R.A., Dec) = (170.442 deg, -61.632 deg) = (11 21 46, -61 37 55) (J2000)

with a statistical 90% C.L. elliptical error region with long and short
radii of 0.49 deg and 0.39 deg, respectively.  The roll angle of long axis
from the north direction is 73.0 deg counterclockwise.  There is an additional
systematic uncertainty of 0.1 deg (90% containment radius).  The determined
position deviates by &sim;0.3 deg from the known location of 1A 1118-616.
Although the X-ray flux averaged over these scans was 31 &plusmn; 4 mCrab
(4.0-10.0keV, 1 sigma error), there is a possible increasing trend of &sim;9
mCrab day<sup>-1</sup>.

The obtained position error circle contains the position of 1A 1118-61
which exhibited a giant X-ray outburst in 2026 January/February (ATel #17608,
#17613, #17615, #17616, #17620, #17626, #17627, #17667, #17690).  However,
the flux of 1A 1118-61 during the onset phase of the last giant outburst
increased rapidly and did not show such a moderate increase.

On the other hand, the relatively constant faint flux (&sim;20-30 mCrab)
lasting for a week is similar to the low-state activity observed in another
Be/X-ray binary pulsar, 2S 1417-624 (ATel #12841).  Therefore, 1A 1118-616
could still be a candidate of this brightening.

The absence of periodic dip structures in the light curve also allows us
to exclude the possibility of the contamination from the nearby source
Cen X-3 which exhibits the periodic eclipse events synchronized with its
orbital period of &sim;2.08 day (Klawin et al. 2023).

Based on the above, the triggered event could be a weak X-ray activity
of 1A 1118-616.  The possibility of a new transient, however, cannot be
excluded.  Thus, we have tentatively named this transient MAXI J1122-616.
Multi-wavelength follow-up observations are strongly encouraged to clarify
the nature of this source.

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