EP260213a
GCN Circular 43823
Subject
EP260213a: Mephisto optical upper limits
Date
2026-02-25T04:33:50Z (16 days ago)
From
Brajesh Kumar at SWIFAR, YNU <brajesh@ynu.edu.cn>
Via
Web form
Guowang Du, Ziwei Li, Zhenfei Qin, Jialong Zhou, Yu Pan, Xingzhu Zou, Xinlei Chen, Brajesh Kumar, Yuan Fang, Jinghua Zhang, Xufeng Zhu, Tao Wang, Xinzhong Er, Yuanpei Yang, Xiangkun Liu, Xiaowei Liu (SWIFAR, YNU) report on behalf of the Mephisto Team:
The 1.6m Multi-channel Photometric Survey Telescope (Mephisto) of Yunnan University, located at the Lijiang Observatory, was triggered at 2026-02-13T20:05:57 (~7.2 min after the EP/WXT trigger) to observe the field of EP260213a (Yang et al., GCN 43729; Li et al., GCN 43730). A set of simultaneous multi-band (ugi and vrz) images was collected. In our stacked frames, no new candidate was detected within the EP/FXT localization (Li et al., GCN 43730) and the upper limits (3 sigma) are listed below. These results are consistent with previously reported non-detection by Cotter et al. (GCN 43728), Wu et al. (GCN 43731), Maksut et al. (GCN 43732), Pankov et al. (GCN 43733), Li et al. (GCN 43734), Aryan et al. (GCN 43735), Fortin et al. (GCN 43737), Lipunov et al. (GCN 43738) and Eyles-Ferris et al. (GCN 43739).
---------------------------------------------------
Start_Time(UT) | Band | Exp(s) | LimMag (AB)
---------------------------------------------------
2026-02-13T20:11:30 | u | 45.0*8 | >22.68
2026-02-13T20:05:57 | v | 45.0*5 | >22.62
2026-02-13T20:11:33 | g | 45.0*8 | >23.51
2026-02-13T20:05:59 | r | 45.0*5 | >23.41
2026-02-13T20:13:07 | i | 45.0*8 | >22.84
2026-02-13T20:05:59 | z | 45.0*5 | >21.85
---------------------------------------------------
Mephisto (Multi-channel Photometric Survey Telescope) is a 1.6-m wide-field multi-channel telescope, the first of its type in the world, capable of imaging the same field of view in three optical bands simultaneously. The facility is operated by the South-Western Institute for Astronomy Research (SWIFAR), Yunnan University. It provides real-time, high-quality colors of stellar objects. The Mephisto mosaic cameras were installed in October 2025. The first light was achieved in all three channels on 10 October 2025 and presently, these are under the commissioning phase. All the data have been reduced by the Mephisto data processing pipeline. Here, we note that the current data processing pipeline is still at a preliminary stage, with flux calibration precision in each band at the level of about 5% or even higher.
GCN Circular 43739
Subject
EP260213a: Liverpool Telescope optical upper limits
Date
2026-02-14T19:02:18Z (a month ago)
From
Rob Eyles-Ferris at U of Leicester <raje1@leicester.ac.uk>
Via
Web form
R. A. J. Eyles-Ferris and R. L. C. Starling (Leicester) report on behalf of a larger collaboration:
We observed the field of EP260213a (Yang et al., GCN 43729; Li et al., GCN 43730) with the 2m Liverpool Telescope on La Palma using the IO:O instrument. We obtained 6x150s exposures in each of the SDSS r’ and SDSS g’ filters starting at 2026-02-14 02:35:02 UT, approximately 6.6 hours after the X-ray detection.
Within the EP/FXT localisation (Li et al., GCN 43730), we detect no new sources in our stacked images consistent with the results of Cotter et al. (GCN 43728), Wu et al. (GCN 43731), Maksut et al. (GCN 43732), Pankov et al. (GCN 43733), Li et al. (GCN 43734), Aryan et al. (GCN 43735), Fortin et al. (GCN 43737) and Lipunov et al. (GCN 43738).
We derive 3-sigma upper limits of r’ > 23.2 and g’ > 23.5 with photometry calibrated to Pan-STARRS and not corrected for Galactic extinction.
GCN Circular 43738
Subject
EP260213a: Global MASTER-Net observations report
Date
2026-02-14T17:27:19Z (a month 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-Tunka robotic telescope [1] located in Russia (Applied Physics Institute, Irkutsk State University) was pointed to the EP260213a ( EP Team et al., GCN 43729) errorbox 46720 sec after notice time and 70986 sec after trigger time at 2026-02-14 15:41:46 UT, with upper limit up to 19.8 mag. The observations began at zenith distance = 58 deg. The sun altitude is -47.0 deg.
The galactic latitude b = 56 deg., longitude l = 253 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=3135046
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
71017 | 2026-02-14 15:41:46 | MASTER-Tunka | (11h 05m 53.43s , +05d 16m 04.4s) | C | 60 | 15.9 |
71017 | 2026-02-14 15:41:46 | MASTER-Tunka | (11h 06m 18.51s , +05d 10m 06.9s) | C | 60 | 19.8 |
72842 | 2026-02-14 16:12:12 | MASTER-Tunka | (11h 05m 50.85s , +05d 10m 39.1s) | C | 60 | 15.4 |
72842 | 2026-02-14 16:12:12 | MASTER-Tunka | (11h 06m 16.94s , +05d 03m 46.6s) | C | 60 | 19.6 |
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 43737
Subject
EP260213a: COLIBRÍ optical upper limits
Date
2026-02-14T16:52:46Z (a month ago)
From
Alan Watson at UNAM <alan@astro.unam.mx>
Via
Web form
Francis Fortin (IRAP), Asuka Kuwata (UNAM), Alan M. Watson (UNAM), Noémie Globus (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Edilberto Aguilar-Ruiz (UNAM), Jean-Luc Atteia (IRAP), Camila Angulo (UNAM), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Rosa L. Becerra (UNAM), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM), Leonardo García García (UNAM), Ramandeep Gill (UNAM), Nikos Mandarakas (LAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), Fredd Sánchez Álvarez (UNAM), Benjamin Schneider (LAM), and Antonio de Ugarte Postigo (LAM) report:
We imaged the field of the EP260213a (Yang et al., GCN Circ. 43729; Li et al., GCN Circ. 43730) using the DDRAGO two-channel wide-field imager on the COLIBRÍ telescope. We observed from 2026-02-14 07:09:32 to 12:08:00 UTC (from 11.18 to 16.17 hours after the trigger) and obtained 92 minutes of simultaneous exposure in the r and z filters.
The data were reduced, calibrated, and analyzed with the COLIBRÍ ASU pipeline. The photometry was calibrated using nearby stars from the PanSTARRS DR1 catalog, is in the AB system, and is not corrected for Galactic extinction.
In the stacked image, and in comparison to the PS1 and Legacy Survey images (Dey et al. 2019), we do not detect any new source at the FXT source position (Li et al., GCN Circ. 43730) down to the following 5-sigma limits:
r > 24.0,
z > 22.6.
This upper limit is consistent with the ones reported by Wu et al. (GCN Circ. 43731), Maksut et al. (GCN Circ. 43732), Pankov et al. (GCN Circ. 43733), Li et al. (GCN Circ. 43734), and Aryan et al. (GCN 43735).
We have chosen to publish 5-sigma limits as the FXT region contains about 100 independent PSFs. The false-alarm probability for 3-sigma positive fluctuations in a region this size is about 0.13. For 5-sigma fluctuations, it is about 3e-5.
We thank the staff of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir and the COLIBRÍ and DDRAGO engineering teams.
COLIBRÍ is an astronomical observatory developed and operated jointly by France (AMU, CNES and CNRS) and Mexico (UNAM and SECIHTI). It is located at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir, Baja California, Mexico.
GCN Circular 43735
Subject
EP260213a: Optical upper limits with Kinder observations
Date
2026-02-14T13:48:03Z (a month ago)
From
Amar Aryan at National Central University, Institute of Astronomy (NCUIA) <amararyan941@gmail.com>
Via
Web form
A. Aryan, C.-S. Lin, T.-W. Chen (all NCU), A. K. H. Kong (NTHU), J. H. Gillanders, S. J. Smartt (both Oxford), Y. J. Yang (NYUAD), Y.-H. Lee, A. Sankar.K, M.-H. Lee, C.-H. Lai, Y.-C. Pan, C.-C. Ngeow, W.-J. Hou, H.-Y. Hsiao, H.-C. Lin, J.-K. Guo (all NCU), S. Yang, Z. N. Wang, L. L. Fan, G. H. Sun (all HNAS), H.-W. Lin (UMich), H. F. Stevance, S. Srivastav, L. Rhodes (all Oxford), M. Nicholl, M. Fulton, T. Moore, K. W. Smith, C. Angus, A. Aamer (all QUB), A. Schultz, and M. Huber (both IfA, Hawaii) report:
We observed the field of the fast X-ray transient EP260213a (Yang et al. GCN 43729, Li et al. GCN 43730) using the 40cm SLT at the Lulin observatory, as part of the Kinder collaboration (Chen & Yang et al. 2025, ApJ, 983, 86, doi:10.3847/1538-4357/adb428). The first SLT epoch of observations in r-band started at 20:12 UTC on 13th of February 2026 (MJD 61084.842), 0.22 hr after the EP-WXT trigger.
We utilized the astroalign (Beroiz et al. 2020, A&C, 32, 100384) and astropy (Astropy Collaboration et al. 2022, ApJ, 935, 167) packages to align and stack the individual frames. We used the Python-based AutoPhOT package (Brennan & Fraser 2022, A&A, 667, A62) to perform template subtraction with the DESI Legacy Survey (Dey et al. 2019, AJ 157, 168) DR10 using the 'SFFT' (Hu et al. 2022, ApJ, 936, 157) algorithm. Either in the stacked frame or in the difference image, we do not detect any new or uncataloged sources within the 10" refined EP-FXT localization circle.
Moreover, we used AutoPhOT to perform PSF photometry. The details of the observations and the measured 3-sigma upper limits (in the AB system) are as follows:
Telescope | Filter | MJD (start) | t-t0 (hr) | Exposure (s) | Magnitude | avg. Seeing | med. Airmass
SLT | r | 61084.842 | 0.22 | 300 * 18 | >21.6 | 2".5 | 1.70
The non-detection in our observations is consistent with those reported by Cotter et al. (GCN 43728), Wu et al. (GCN 43731), Maksut et al. (GCN 43732), Pankov et al. (GCN 43733), and Li et al. (GCN 43734).
The presented magnitude is calibrated using the field stars from the ATLAS-RefCat2 catalog from MAST (Tonry J. L. et al. 2018, ApJ, 867, 105) and is not corrected for the expected Galactic foreground extinction of A_r = 0.106 mag in the direction of the transient (Schlafly & Finkbeiner 2011). The methodology, details on the Lulin observatory telescopes, and a compilation of our optical follow-up campaign for FXTs discovered within the first year of operation of the Einstein-Probe mission are presented in Aryan et al. 2025, ApJS, 281, 20, doi:10.3847/1538-4365/adfc69.
GCN Circular 43734
Subject
EP260213a: SVOM/VT optical upper limit
Date
2026-02-14T11:22:32Z (a month ago)
From
Huali Li at at NAOC, SVOM <lhl@nao.cas.cn>
Via
Web form
H. L. Li, Y. N. Ma, L. P. Xin, Y. L. Qiu, C. Wu, Z. H. Yao, X. H. Han, Y. Xu, J. Wang, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, L. Lan, J. R. Xu, J. S. Deng, J. Y. Wei (NAOC), J. Palmerio (CEA) report on behalf of the SVOM/VT team.
SVOM/VT performed a Target of Opportunity observation of EP260213a detected by Einstein Probe (Yang et al., GCN 43729; Li et al, GCN 43730). The observation started on 2026-02-13T21:19:03 UTC, 1.346 hours after the trigger, in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously.
No uncatalogued sources were detected in stacked images within the error box of EP-FXT (Yang et al., GCN 43729; Li et al., GCN 43730). The 3 sigma limit magnitudes are derived as follows:
Mid time | Band | Exposure Time | 3 sigma limit magnitude
2.38 hour VT_B 72*50 sec > 23.7 mag
2.39 hour VT_R 67*50 sec > 23.5 mag
Our photometry was in AB magnitude and was not corrected for Galactic extinction.
The nondetection is consistent with the results published previously (Cotter et al., GCN 43728; Wu et al., GCN 43731; Maksut et al., GCN 43732; Pankov et al., GCN 43733).
The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. VT was jointly developed by Xi'an Institute of Optics and Precision Mechanics (XIOPM), CAS and National astronomical observatories (NAOC), CAS.
GCN Circular 43733
Subject
EP260213a: Mondy R-band optical upper limit
Date
2026-02-14T10:48:57Z (a month ago)
Edited On
2026-02-15T01:36:42Z (a month ago)
From
Nicolai Pankov at IKI <colinsergesen@gmail.com>
Edited By
Vidushi Sharma at NASA GSFC/UMBC <vidushi.sharma@nasa.gov> on behalf of Nicolai Pankov at IKI <colinsergesen@gmail.com>
Via
Web form
N. Pankov (IKI), E. Klunko (ISTP), A. Volnova (IKI), A. Pozanenko (IKI) report on behalf of IKI-GRB-FuN:
We observed the field of a fast X-ray transient EP260213a (Yang et al., GCN 43729) with the AZT-33IK 1.5m telescope of the Sayan Solar Observatory (Mondy) starting on 2026-02-13 20:08:15 (UT). A total of 30x120 sec exposures were taken in the R-band. No optical candidate was detected within refined error circle (Li et al., GCN 43730). Also, no objects from the catalogues (SDSS, PS1, WISE, LS) were found within the error circle. The preliminary photometry and observational details are presented below:
Date UT start t-T0 Exp. Filter Mag. Err. UL
(mid,days) (n*s) (3sigma)
2026-02-13 20:08:15 0.02797 30*120 R n/d n/d 22.2
The photometry was calibrated using nearby stars of USNO-B1.0 and has not been corrected for the Galactic extinction. Our results are consistent with the results published previously (Cotter et al., GCN 43728; Wu et al., GCN 43731; Maksut et al., GCN 43732).
GCN Circular 43732
Subject
EP260213a: NUTTelA-TAO Early Optical Limits
Date
2026-02-14T10:20:16Z (a month ago)
From
Zhanat Maksut at Nazarbayev University <zhanat.maksut@nu.edu.kz>
Via
Web form
Z. Maksut (NU), T. Komesh (NU), D. Berdikhan (NU), E. Abdikamalov (NU), M. Krugov (FAI), K. Baigarin (NU), M. Coughlin (UMN), P. Hello (IJCLAB), S. Antier (IJCLAB), and S. Karpov (FZU) on behalf of the GRANDMA/NUTTelA-TAO:
The Nazarbayev University Transient Telescope at Assy-Turgen Astrophysical Observatory (NUTTelA-TAO) pointed at EP 260213a on receipt of an automated GCN / EP position alert, observing in Sloan g' and i' bands, with the Burst Simultaneous Three-Channel Imager (BSTI; Grossan, Kumar & Smoot 2019, JHEA, 32, 14).
We started observations at 20:05:22 UT on 2026-02-13, 442 seconds after the EP/WXT trigger (J. Yang et al., GCN 43729). No optical source consistent with the EP/WXT (J. Yang et al., GCN 43729) was detected. We report the following results:
start time t-t0(s) UL g' UL i' exposure_time (s)
--------------------------------------------------------------
20:05:43 467 16.3 17.1 50
20:07:04 694 19.6 20.1 300
20:18:05 1505 19.8 20.4 600
t is the middle time, t0 is the EP/WXT trigger time, t-t0 is given in seconds. UL gives the 5 sigma upper limit sensitivity in magnitudes, for images of the given exposure time. Calibration was done with 4 Pan-STARRS catalog stars on our images. No color or other corrections were applied to the values above.
----------------------------------
This research has been funded by the Science Committee of the Ministry of Science and Higher Education of the Republic of Kazakhstan (Grant No. AP26103591). The NUTTelA-TAO Team acknowledges the support of the staff of the Assy-Turgen Astrophysical Observatory, Almaty, Kazakhstan, and the Fesenkov Astrophysical Institute, Almaty, Kazakhstan. GRANDMA is a worldwide telescope network (grandma.ijclab.in2p3.fr) devoted to the observation of transients in the context of multi-messenger astrophysics (Antier et al. 2020 MNRAS 497, 5518). Kilonova-Catcher (KNC) is the citizen science program of GRANDMA (http://kilonovacatcher.in2p3.fr/).
GCN Circular 43731
Subject
EP260213a: SVOM/C-GFT upper limit
Date
2026-02-14T09:22:49Z (a month ago)
From
SVOM_group <svomgroup@bao.ac.cn>
Via
Web form
C. Wu (NAOC), Z. Kang (CHO), L.P. Xin, X.H. Han, P.P. Zhang, X.M. Lu (NAOC), Z.W. Li, Y. Lv (CHO), R.S. Zhang, Y.J. Xiao, Y.L. Qiu, J. Wang, J.S. Deng, L. Huang, J.Y. Wei (NAOC) report on behalf of the SVOM/C-GFT team:
We observed the field of EP260213a (ID:01709258378) detected by EP/WXT (Yang et al., GCN 43729) with LATIOS on SVOM/C-GFT. Observations started at 2026-02-13T19:58:40 UTC, ~6.78 min after the trigger.
We obtained g, r, and i-band follow-up imaging. After preliminary analysis，no credible candidate was detected within the error box provided by EP/FXT (Li et al., GCN 43730) in our images. The 3-sigma upper limits are:
| Mid_t - T0 (min) | Exposure Time (s) | Band | Upper Limit (AB) |
|---|---|---|---|
| 10.76 | 6×30 | g | 19.9 |
| 13.75 | 11×30 | i | 19.8 |
| 15.28 | 6×30 | r | 19.9 |
The photometry was calibrated against Pan-STARRS1 stars and no correction for Galactic dust extinction was applied.
Our result is consistent with GCN 43728 (Cotter et al.)
We thank the observation assistants Hong-Xu Xue and Bo-Wen Li at Jilin observatory for their excellent support.
The Chinese Ground Follow-up Telescope (C-GFT) for the SVOM mission is located at Jilin Station, Changchun Observatory, National Astronomical Observatories, CAS. It features two instruments: (1) CATCH at the Cassegrain focus with a 21 arcsec x 21 arcsec FOV for simultaneous g/r/i-band imaging, and (2) LATIOS, a 4k x 4k CMOS camera at the prime focus with a 1.28 deg x 1.28 deg FOV that images in g, r, and i bands via filter switching.
GCN Circular 43730
Subject
EP260213a: refined analysis of the EP-FXT observation
Date
2026-02-14T06:39:43Z (a month ago)
From
EP Team at NAOC/CAS <ep_ta@bao.ac.cn>
Via
Web form
R.-Z. Li (YNAO, CAS), J. Yang (ZZU), X. Tian (GXU), W. D. Zhang (NAOC) on behalf of the Einstein Probe (EP) team:
The fast X-ray transient EP260213a triggered the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission (Yang et al., GCN 43729), and was followed by NOT (Cotter et al., GCN 43728). The autonomous observation by the Follow-up X-ray Telescope (FXT) was performed at 2026-02-13T20:03:06 (UTC), about 5 minutes after T0. The effective exposure time of this observation is around 4.7 ks. The on-ground analysis shows that an uncatalogued source was detected at R.A. = 167.0070, DEC = 3.9470 (J2000) with an uncertainty of 10 arcsec in radius (90% C.L. statistical and systematic).
The average 0.5-10 keV spectrum can be fitted with an absorbed power law with a fixed Galactic hydrogen column density of 5.60 × 10^20 cm^-2 and a photon index of 2.18 (-0.15/+0.16). The derived average unabsorbed 0.5-10 keV flux is 1.77 (-0.17/+0.19) × 10^(-12) erg/cm^2/s. The uncertainties are at the 90% confidence level for the above parameters.
Further FXT follow-up observations have been arranged.
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 43729
Subject
EP260213a: Einstein Probe detection of a fast X-ray transient
Date
2026-02-14T02:42:27Z (a month ago)
From
EP Team at NAOC/CAS <ep_ta@bao.ac.cn>
Via
Web form
J. Yang (ZZU), R.-Z. Li (YNAO, CAS), X. Tian (GXU), W. D. Zhang (NAOC) on behalf of the Einstein Probe (EP) team:
We report on the detection of a fast X-ray transient by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission, designated EP260213a. The transient triggered EP-WXT (ID: 01709258378) at 2026-02-13T19:58:40 (UTC). The WXT position of the source is R.A. = 167.008 deg, DEC = 3.965 deg (J2000) with an uncertainty of 3 arcmin in radius (90% C.L. statistical and systematic). The preliminary analysis of the WXT data shows that the event started at T0=2026-02-13T19:58:00 (UTC), and lasted for approximately 40 seconds. The average WXT 0.5-4 keV spectrum can be fitted with an absorbed power law with a fixed Galactic hydrogen column density of 5.60 × 10^20 cm^-2 and a photon index of 0.6 (+/-0.6). The derived average unabsorbed 0.5-4 keV flux is 1.4 (-0.4/+0.5) × 10^(-9) erg/s/cm^2.
A follow-up observation with the Follow-up X-ray Telescope (FXT) was performed automatically. Within the WXT error circle, an uncatalogued X-ray source was detected at R.A. = 167.0083 deg, DEC = 3.9451 deg (J2000) with an uncertainty of 20 arcsec in radius (90% C.L. statistical and systematic).
Further information will be updated when the telemetry data is received.
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).