EP250807a
GCN Circular 41311
Subject
EP250807a: EP-FXT follow-up observation upper limit
Date
2025-08-10T04:22:40Z (2 months ago)
From
EP Team at NAOC/CAS <ep_ta@bao.ac.cn>
Via
Web form
Y. Wang (PMO, CAS), Y. Q. Zhao (USTC,PRIC), H. Q. Cheng, Z. X. Ling (NAOC) on behalf of the Einstein Probe (EP) team:
EP-FXT performed a follow-up observation of EP250807a (Wang et al. GCN 41277) at 2025-08-08 10:27:06 (UTC), about 11 hours after WXT trigger, with an exposure time of 2972 s. No significant X-ray source was detected by the FXT within the WXT error circle, the flux upper limit is 7.4e-14 erg/cm^2/s in the 0.5-10 keV.
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 41308
Subject
EP250807a: Global MASTER-Net observations report
Date
2025-08-09T21:49:54Z (2 months ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
Via
email
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, I. Gorbunov (Lomonosov MSU),
O.Gress, N.Budnev (ISU),
C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
A.Sosnovskij (CrAO),
A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity),
D.Buckley (SAAO),
R.Rebolo (The Instituto de Astrofisica de Canarias),
L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez,
A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory)
MASTER-Kislovodsk robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) was pointed to the EP250807a ( EP Team et al., GCN 41277) errorbox 36084 sec after notice time and 64631 sec after trigger time at 2025-08-08 17:30:13 UT, with upper limit up to 17.1 mag. Observations started at twilight. The observations began at zenith distance = 33 deg. The sun altitude is -11.5 deg.
The galactic latitude b = 7 deg., longitude l = 45 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=2963680
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
64661 | 2025-08-08 17:30:13 | MASTER-Kislovodsk | (18h 43m 28.97s , +14d 43m 36.5s) | C | 60 | 17.1 |
64831 | 2025-08-08 17:33:02 | MASTER-Kislovodsk | (18h 43m 28.20s , +14d 42m 55.0s) | C | 60 | 17.1 |
65007 | 2025-08-08 17:35:59 | MASTER-Kislovodsk | (18h 43m 24.84s , +14d 43m 09.9s) | C | 60 | 17.1 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
GCN Circular 41286
Subject
EP250807a: NTT z-band optical upper limit
Date
2025-08-08T12:10:28Z (2 months ago)
From
Agnes van Hoof at Radboud University <agnes.vanhoof@ru.nl>
Via
Web form
A.P.C. van Hoof (Radboud), J.N.D. van Dalen (Radboud), D. B. Malesani (DAWN/NBI and Radboud), R. A. J. Eyles-Ferris (U of Leicester), A. Martin-Carrillo (UCD) and P. G. Jonker (Radboud) report on behalf of a larger collaboration:
We observed the field of EP250807a (Wang et al., GCN 41277