GCN Circular 24093
A. D'Ai (INAF-IASFPA), A. Y. Lien (GSFC/UMBC), A. A. Breeveld (MSSL-UCL) report on behalf of the Swift team: Using Swift/BAT data set from T-60 to T+243 sec from the recent telemetry downlink, we report further analysis of the possible GRB 190409A (trigger #897653, D'Ai et al. GCN 24081). The BAT image significance has decreased to 3.7 sigma, and thus is consistent with a noise fluctuation. We have analysed 2.8 ks of Photon Counting (PC) mode XRT data, collected between T0+3.0 ks and T0+10.2 ks. One uncatalogued X-ray source has been detected but outside the BAT error circle at 4.3 arcmin from the Swift/BAT position reported in GCN 24081. The source is below the RASS limit and shows no definitive signs of fading. Details of this source are given below: Source 1: RA (J2000.0): 325.0326 = 21:40:7.82 Dec (J2000.0): -46.6064 = -46:36:23.0 Error: 7.7 arcsec (radius, 90% conf.) Count-rate: (4.3 [+1.8, -1.4])e-3 ct s^-1 Distance: 276 arcsec from Swift/BAT position. The Swift/UVOT began settled observations of the field of GRB 190409A with the white filter 2950 s after the BAT trigger (D'Ai et al., GCN Circ. 24081). No optical afterglow is detected in the initial UVOT exposure. Given the lowered significance of the BAT trigger from the ground analysis, the lack of a clear X-ray/UVOT counterpart within the BAT error circle, we believe that GRB 190409A was most likely a spurious event.