////////////////////////////////////////////////////////////////////// TITLE: GCN/INTEGRAL NOTICE NOTICE_DATE: Thu 25 Aug 16 09:40:04 UT NOTICE_TYPE: INTEGRAL SPI ACS Trigger TRIGGER_NUM: 7539, Sub_Num: 0 GRB_INTEN: 11.28 [sigma] GRB_TIME: 34769.12 SOD {09:39:29.12} UT GRB_DATE: 17625 TJD; 238 DOY; 16/08/25 COMMENTS: INTEGRAL SPI_ACS GRB Trigger. COMMENTS: Time_Scale=0.2000 and Time_Error=0.1000. COMMENTS: The SPIACS lightcurve can be found at: COMMENTS: ftp://isdcarc.unige.ch/arc/FTP/ibas/spiacs/2016-08/2016-08-25T09-39-28.9460-14964-23440-0.lc //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19864 SUBJECT: GRB 160825A: Swift ToO observations DATE: 16/08/26 00:38:18 GMT FROM: Phil Evans at U of Leicester P. A. Evans (U. Leicester) reports on behalf of the Swift team: Swift has initiated a ToO observation of the INTEGRAL GRB 160825A. Automated analysis of the XRT data will be presented online at http://www.swift.ac.uk/ToO_GRBs/00020686 Any uncatalogued X-ray sources detected in this analysis will be reported on this website and via GCN COUNTERPART notices. These are not necessarily related to the INTEGRAL event. Any X-ray source considered to be a probable afterglow candidate will be reported via a GCN Circular after manual consideration. Details of the XRT automated analysis methods are detailed in Evans et al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8). This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19870 SUBJECT: GRB 160825A: not localized by Swift DATE: 16/08/26 18:52:44 GMT FROM: David Palmer at LANL D. M. Palmer (LANL) reports on behalf of the Swift team: On 2016-08-25 at 09:39:29, INTEGRAL SPI ACS reported a trigger (#7539) via GCN. Examination of the Swift/BAT count rates at that time showed a simultaneous detection of a short hard burst (duration ~0.1 s, with the detected flux predominantly above 50 keV). On-board analysis of the data showed that the highest-significance peak in the corresponding image was at a location ra,dec = 251.982, -7.833 (J2000) with a ~5 arcmin error radius. This peak is of marginal significance (5.6 sigma) and did not trigger an automated follow-up observation. A preliminary analysis of the Time-of-Arrival difference between INTEGRAL and BAT lightcurves did not exclude this location. Therefore, this was considered a possible GRB localization and a ToO observation was requested. Swift-XRT performed follow-up observations of this location, collecting 2.0 ks of Photon Counting (PC) mode data between T0+55.9 ks and T0+62.2 ks. No X-ray sources have been detected within the 296 arcsec radius BAT error circle. The 3-sigma upper limit in the field is 0.004 ct s^-1, corresponding to a 0.3-10 keV observed flux of 1.5e-13 erg cm^-2 s^-1 (assuming a typical GRB spectrum). An uncatalogued source was detected, however this was too far from the GRB position to be the afterglow. The results of the XRT-team automatic analysis of the XRT observations, including a position-specific upper limit calculator, are available at http://www.swift.ac.uk/ToO_GRBs/00020686. A more detailed analysis of the light curve TOA difference also conclusively excludes the BAT location as the true burst position. (Dmitry Svinkin, private communication). Based on these observations and analyses, we can exclude the marginal image peak location as being the GRB location. The simultaneous INTEGRAL and BAT detections proves that there was a short GRB at that time, but it was most likely outside of the BAT's imaging field of view. [GCN OPS NOTE(26aug16): Per author's request, the mispelling and missing word 'source' were fixed.]