TITLE:   GCN CIRCULAR
NUMBER:  35786
SUBJECT: Transient EPW20240219aa: upper limit in gamma-ray range from SPI-ACS/INTEGRAL observations
DATE:    24/02/24 10:25:23 GMT
FROM:    Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>

P. Minaev (IKI), A. Pozanenko (IKI), I. Chelovekov (IKI), S. Grebenev (IKI) report on behalf of GRB IKI FuN:

We analyzed publicly available SPI-ACS/INTEGRAL data to search for possible counterpart of the X-ray flare EPW20240219aa detected by Einstein Probe (ATel 16463; ATel 16472), which is also found in Fermi/ GBM   (GCN 35773, GCN 35776),  /SwiftBAT (DeLaunay et al., GCN 35784 and Insight-HXMT/HE
 (Cai et al., GCN 35785).  We did not find any statistically significant event in time interval of (-1000, 1000) s since 2024-02-19 06:21:42 (UTC). The non-detection of the X-ray flare EPW20240219aa could be result from low sensitivity of SPI-ACS in the direction of the source of EPW20240219aa (the angle between an the angle between axis of ACS is 159 degrees). Using cross-calibration model of SPI-ACS effective area obtained in [1], we estimated the 3 sigma fluence upper limit for the EPW20240219aa with the duration of 50 s and E_peak = 230 keV (GBM candidate, GCN 35773, GCN 35776) to be F = 5.2*E-6 erg/cm**2 in the 10-1000 keV energy band.
 [1] – Minaev et al., MNRAS, 525, 2411, 2023