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To: stefano@bicar.it
From: atel@astronomerstelegram.org
Subject: ATel  17316, 17317
Message-Id: <20250801071052.98E3F288088C@server.astronomerstelegram.org>
Date: Fri,  1 Aug 2025 03:10:52 -0400 (EDT)

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Posted: Within the last 24 hours
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ATEL #17316							     ATEL #17316

Title:	Fermi-LAT detection of renewed gamma-ray activity from the
		FSRQ PKS 1725+123
Author:	S. Rani (Michigan Technological University), G. La Mura (INAF
		- Astronomical Observatory of Cagliari), on behalf of the Fermi Large
		Area Telescope Collaboration
Queries:	rani@mtu.edu
Posted:	31 Jul 2025; 19:06 UT
Subjects:Gamma Ray, >GeV, AGN, Blazar

The Large Area Telescope (LAT), one of the two instruments on the Fermi
Gamma-ray Space Telescope, has observed renewed gamma-ray activity from
a source positionally consistent with the flat-spectrum radio quasar PKS
1725+123, also known as 4FGL J1728.0+1216 (Abdollahi et al. 2022, ApJS,
260, 53), with coordinates R.A. = 262.02938 deg, Dec. = +12.26097 deg (J2000;
Xu et al. 2019, ApJS, 242, 5), and redshift z = 0.568 (Nanci et al. 2022,
A&A, 663, A129).

Preliminary analysis indicates that this source was in an elevated gamma-ray
emission state on July 30, 2025, with a daily averaged gamma-ray flux (E
> 100 MeV) of (0.7 +/- 0.2) X 10^-6 photons cm^-2 s^-1 (statistical uncertainty
only). This corresponds to a flux increase of a factor of more than 30
relative to the average flux reported in the fourth release of the Fourth
Fermi-LAT catalog (4FGL-DR4, Ballet et al. 2024, arXiv:2307.12546). This
is the highest LAT daily flux ever observed for this source. The corresponding
photon index of 1.9 +/- 0.1 indicates a significantly harder spectrum than
the 4FGL-DR4 value of 2.47 +/- 0.05 (Ballet et al. 2023, arXiv:2307.12546).
The Fermi-LAT Collaboration has previously reported flaring activity from
this source in ATel #17094.

Because Fermi normally operates in an all-sky scanning mode, regular gamma-ray
monitoring of this source will continue. A preliminary light curve for
PKS 1725+123 is available at the <a href="https://fermi.gsfc.nasa.gov/ssc/data/access/lat/LightCurveRepository/source.html?source_name=4FGL_J1728.0+1216">Fermi-LAT
Light-Curve Repository</a>. We encourage multifrequency observations of
this source. For this source, the Fermi-LAT contact person is Pietro Monti-Guarnieri
(pietro.monti-guarnieri@phd.units.it).

The Fermi-LAT is a pair conversion telescope designed to cover the energy
band from 20 MeV to greater than 300 GeV. It is the product of an international
collaboration between NASA and DOE in the U.S. and many scientific institutions
across France, Italy, Japan and Sweden.

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Password Certification: Giovanni La Mura (giovanni.lamura@inaf.it)
https://www.astronomerstelegram.org/?read=17316
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ATEL #17317							     ATEL #17317

Title:	Einstein Probe detection of a new outburst from IGR J20155+3827
Author:	Q. C. Liu (THU), R. Z. Li (YNAO, CAS), B. B. Zhang, Y. Liu
		(NAO, CAS) on behalf of the Einstein Probe (EP) team 
Queries:	ep_ta@bao.ac.cn
Posted:	1 Aug 2025; 06:06 UT
Subjects:X-ray, Transient

We report on the detection of a possible new X-ray outburst from the High
Mass X-ray Binary (HMXB) IGR J20155+3827, by the Wide-field X-ray Telescope
(WXT) on board the Einstein Probe (EP) mission. The source exhibited a
recent flux increase since 2025-07-31 17:25:35 (UTC). The position of the
source is R.A. = 303.863 deg, DEC = 38.424 deg (J2000) with an uncertainty
of 2.6 arcmin in radius (90% C.L. statistical and systematic), which is
99 arcsec from the HMXB IGR J20155+3827, indicating the possible association
between the two. The WXT spectra around the detection time can be simultaneously
fitted by an absorbed blackbody plus power-law with a blackbody temperature
of 0.13 (+0.04/-0.03) keV and a neutral hydrogen column density of 1.2
(+0.7/-0.4)x 10^22 cm^-2. The derived unabsorbed flux in 0.5-4 keV is 0.9
(+2.5/-0.6) x 10^-9 erg/s/cm^2 in the latest observation and 0.4 (+1.2/-0.3)
x 10^-10 erg/s/cm^2 in the first observation. The photon index cannot be
well constrained.

We note that IGR J20155+3827 exhibited outbursts in 2024 (ATel #16730).
The last observation was reported by EP team on July, 2024 with a flux
of 1.0(+0.3/-0.2)x10^-10 erg/s/cm^2 in 0.5-4 keV (ATel #16730). Multi-wavelength
follow-up observations are encouraged.

Launched on January 9, 2024, EP is a space X-ray observatory to monitor
the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook
of X-ray and Gamma-ray Astrophysics).

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Password Certification: Yuan Liu (liuyuan@bao.ac.cn)
https://www.astronomerstelegram.org/?read=17317
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