EP260822a
GCN Circular 45448
Subject
EP260822a: Global MASTER-Net observations report
Date
2026-08-26T16:05:11Z (7 days ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
Via
email
D.Buckley (SAAO),
M. Segura, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA)
O.Gress, N.Budnev(ISU)
V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko,
G.Antipov, A.Sankovich, Yu.Tselik, Ya..Kechin, V.Senik, A.Chasovnikov, K.Labsina (Lomonosov MSU)
A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity)
A.Sosnovskij (CrAO RAS)
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory)
L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez,
A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory)
R.Rebolo (The Instituto de Astrofisica de Canarias)
MASTER-SAAO robotic telescope [1] located in South Africa (South African Astronomical Observatory) was pointed to the EP260822a ( EP Team at NAOC/CAS <ep_ta@bao.ac.cn> et al., GCN 45428) errorbox 1748 sec after notice time and 1 days 28395 sec after trigger time at 2026-08-23 23:09:17 UT, with upper limit up to 19.2 mag. The observations began at zenith distance = 54 deg. The sun altitude is -67.7 deg.
MASTER-OAFA robotic telescope located in Argentina (OAFA observatory of San Juan National University) was pointed to the EP260822a errorbox 15766 sec after notice time and 1 days 42413 sec after trigger time at 2026-08-24 03:02:55 UT, with upper limit up to 16.5 mag. The observations began at zenith distance = 76 deg. The sun altitude is -59.9 deg.
MASTER-Tunka robotic telescope located in Russia (Applied Physics Institute, Irkutsk State University) was pointed to the EP260822a errorbox 55384 sec after notice time and 1 days 82031 sec after trigger time at 2026-08-24 14:03:13 UT, with upper limit up to 18.9 mag. Observations started at twilight. The observations began at zenith distance = 80 deg. The sun altitude is -15.5 deg.
The galactic latitude b = -51 deg., longitude l = 126 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=3488802
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
114825 | 2026-08-23 23:09:17 | MASTER-SAAO | (00h 55m 15.84s , +10d 52m 14.5s) | C | 60 | 19.0 |
126463 | 2026-08-24 02:23:15 | MASTER-SAAO | (00h 54m 54.50s , +10d 57m 32.8s) | C | 60 | 19.2 |
128844 | 2026-08-24 03:02:55 | MASTER-OAFA | (00h 56m 29.45s , +11d 07m 24.6s) | C | 60 | 16.5 |
168461 | 2026-08-24 14:03:13 | MASTER-Tunka | (00h 55m 09.14s , +10d 51m 17.3s) | C | 60 | 18.4 |
168539 | 2026-08-24 14:04:30 | MASTER-Tunka | (00h 55m 16.07s , +10d 50m 17.1s) | C | 60 | 18.4 |
168617 | 2026-08-24 14:05:48 | MASTER-Tunka | (00h 55m 10.04s , +10d 49m 14.1s) | C | 60 | 18.6 |
168694 | 2026-08-24 14:07:06 | MASTER-Tunka | (00h 55m 14.92s , +10d 49m 15.7s) | C | 60 | 18.5 |
168772 | 2026-08-24 14:08:23 | MASTER-Tunka | (00h 55m 12.23s , +10d 50m 60.0s) | C | 60 | 18.5 |
168849 | 2026-08-24 14:09:40 | MASTER-Tunka | (00h 55m 12.23s , +10d 49m 13.1s) | C | 60 | 18.7 |
168926 | 2026-08-24 14:10:58 | MASTER-Tunka | (00h 55m 14.76s , +10d 51m 03.7s) | C | 60 | 18.7 |
169004 | 2026-08-24 14:12:15 | MASTER-Tunka | (00h 55m 09.13s , +10d 50m 02.4s) | C | 60 | 18.7 |
169083 | 2026-08-24 14:13:35 | MASTER-Tunka | (00h 55m 09.51s , +10d 51m 00.1s) | C | 60 | 18.8 |
169161 | 2026-08-24 14:14:53 | MASTER-Tunka | (00h 55m 15.19s , +10d 49m 58.1s) | C | 60 | 18.8 |
169238 | 2026-08-24 14:16:10 | MASTER-Tunka | (00h 55m 10.13s , +10d 48m 55.8s) | C | 60 | 18.8 |
169315 | 2026-08-24 14:17:26 | MASTER-Tunka | (00h 55m 15.87s , +10d 49m 04.0s) | C | 60 | 18.9 |
169392 | 2026-08-24 14:18:43 | MASTER-Tunka | (00h 55m 12.23s , +10d 50m 34.5s) | C | 60 | 18.8 |
169469 | 2026-08-24 14:20:01 | MASTER-Tunka | (00h 55m 12.26s , +10d 48m 50.4s) | C | 60 | 18.9 |
169548 | 2026-08-24 14:21:20 | MASTER-Tunka | (00h 55m 15.11s , +10d 50m 40.8s) | C | 60 | 18.9 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
[1] - V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina & A.S.Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp.
http : // www.pereplet.ru/lipunov/625.html
GCN Circular 45433
Subject
EP260822a: EP-FXT non-detection and upper limit
Date
2026-08-24T05:19:05Z (9 days ago)
From
EP Team at NAOC/CAS <ep_ta@bao.ac.cn>
Via
Web form
J. P. Feng, B. Zhang (USTC), Y. Q. Zhao (PRIC, USTC) and H. Sun (NAO, CAS) on behalf of the Einstein Probe (EP) team:
EP-FXT observed the field of EP260822a (Feng et al., GCN 45428) for 2825 seconds starting at 2026-08-23T05:39:06, around 13.5 hours after the detection by EP-WXT. No significant X-ray source is detected within the 2.6 arcmin radius of the EP-WXT position (Feng et al., GCN 45428) . The derived 0.5-10 keV flux upper limit is 7.55e-14 erg/cm^2/s, assuming a powerlaw intrinsic emission with a photon index of 2 and fixed galactic absorption.
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).
GCN Circular 45428
Subject
EP260822a: Einstein Probe detection of a fast X-ray transient
Date
2026-08-23T08:30:22Z (10 days ago)
From
EP Team at NAOC/CAS <ep_ta@bao.ac.cn>
Via
Web form
J. P. Feng, B. Zhang (USTC), Y. Q. Zhao(USTC,PRIC), H. Sun (NAO,CAS) on behalf of the Einstein Probe (EP) team:
We report the detection of a fast X-ray transient by the Wide-field X-ray Telescope (WXT) onboard the Einstein Probe (EP), designated EP260822a. EP-WXT first detected the current outburst at 2026-08-22T15:16:02 (UTC), with a flux of about 4.81×10^-11 erg/cm^2/s, located at (R.A., DEC) = (14.334 deg, 11.275 deg) and (Galactic I, b) = (125.259 deg, -51.570 deg), with a 90% positional uncertainty radius of 2.6 arcmin. Short-timescale variation is observed during the ~700s WXT exposure. The transient lasts for around 350 seconds.
The average WXT 0.5-4 keV spectrum can be fitted with an absorbed power law with a hydrogen column density of 0.78 (-0.59/+1.26) x10^22 cm^-2, and a photon index of 3.07 (-1.75/+4.08) (90% C.L. statistical and systematic). The derived average unabsorbed 0.5-4 keV flux is 2.23 (-1.47/+54.17) x 10^-10 erg s^-1 cm^-2. There is no X-ray history detection within the WXT error circle. We also note that we can not rule out the possibility that EP260822a might be the stellar flare of the star G 2-7, which is within the WXT error circle.
Follow-up observations by EP-FXT have been scheduled. Multi-wavelength follow-up observations are encouraged to identify the nature of this likely new X-ray transient.
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).