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GCN Circular 38056

Subject
LIGO/Virgo/KAGRA S241102br: EP-WXT X-ray follow-up and flux limits
Date
2024-11-03T10:19:11Z (20 days ago)
From
EP Team at NAOC/CAS <ep_ta@bao.ac.cn>
Via
Web form
Q. Y. Wu (NAO, CAS), J. Mao(YNAO, CAS), Y. F. Liang (PMO, CAS), Q. C. Liu (THU), R. D. Liang, D. H. Zhao, H. N. Yang, W. Yuan (NAO, CAS) report on behalf of the Einstein Probe team:

Following on the trigger of the detection of the gravitational-wave (GW) event S241102br (LVK Collaboration, GCN 38043Not found
 
 
), we carried out a target-of-opportunity observation of the GW sky region with the Wide-field X-ray telescope(WXT) on board the Einstein Probe (EP). The observation started at 2024-11-02 15:44:04 (UTC), about 3 hours after the trigger of the GW event, lasting for around 5 hours. The 90% credible region of the event was fully covered by the large field-of-view of WXT, centering at the nominal GW source position at (RA=23h00m, Dec=+40d28m). The total effective exposure time is about 8 ks within the source credible region. No new X-ray source is found in this observation. This observation sets upper limits on the 0.5-4 keV flux in the source credible region to be approximately 2.42 x 10^(-12) erg/cm^2/s (90%. C.L.). Furthermore, we derived upper limits (see the Table below) for the top 20 galaxies from the galaxy list within the 90% volume reported by Cook et al. (GCN 38044Not found
 
 
). For queries on more information about this observation and the upper limits, please contact Qinyu Wu at the EP science center (ep_ta@nao.cas.cn).

       galaxy name       |    ra     |    dec   |  flux upper limit (0.5-4 keV)
                         |    deg    |    deg   |  ergs/cm^2/s
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WISEAJ225919.78+394535.0 | 344.83242 | 39.75972 | 1.42E-12
WISEAJ225952.51+442917.7 | 344.96871 | 44.48825 | 1.51E-12
WISEAJ230520.33+400018.8 | 346.33458 | 40.00514 | 1.88E-12
WISEAJ230012.95+415343.7 | 345.05417 | 41.89553 | 1.86E-12
WISEAJ225938.70+415648.8 | 344.91125 | 41.94689 | 1.51E-12
WISEAJ230201.05+423126.9 | 345.50446 | 42.52411 | 1.09E-12
WISEAJ225743.15+404134.4 | 344.42971 | 40.69286 | 1.19E-12
WISEAJ225708.96+394204.3 | 344.28733 | 39.70117 | 2.25E-12
WISEAJ225745.81+373140.1 | 344.44088 | 37.52783 | 1.63E-12
WISEAJ230533.61+424929.5 | 346.39000 | 42.82489 | 1.91E-12
WISEAJ230113.12+354411.0 | 345.30462 | 35.73639 | 1.65E-12
WISEAJ230419.52+423037.8 | 346.08129 | 42.51047 | 1.07E-12
WISEAJ230200.39+415916.5 | 345.50162 | 41.98792 | 1.35E-12
WISEAJ225832.97+415012.0 | 344.63725 | 41.83658 | 1.95E-12
WISEAJ230133.36+394404.8 | 345.38892 | 39.73472 | 1.13E-12
WISEAJ230257.02+393909.0 | 345.73754 | 39.65240 | 1.99E-12
WISEAJ225902.80+411053.6 | 344.76171 | 41.18158 | 1.49E-12
WISEAJ225942.19+421403.0 | 344.92588 | 42.23417 | 1.17E-12
WISEAJ230431.87+440856.3 | 346.13275 | 44.14900 | 1.77E-12
WISEAJ230530.98+394323.1 | 346.37912 | 39.72308 | 1.73E-12
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Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with onboard X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics). EP is an international collaborative mission led by the Chinese Academy of Sciences (CAS) and participated by the European Space Agency (ESA), the Max-Planck Institute for Extraterrestrial Physics (MPE) in Germany and the Centre National d’Etudes Spatiales (CNES) in France.