//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 30296 SUBJECT: Swift Trigger 1057131: detection of a burst from SGR Swift J1555.2-5402 DATE: 21/06/21 17:28:59 GMT FROM: David Palmer at LANL M. G. Bernardini (INAF-OAB), J.D. Gropp (PSU), J. A. Kennea (PSU), N. J. Klingler (PSU), N. P. M. Kuin (UCL-MSSL), S. Laha (GSFC/UMBC/CRESST), A. Y. Lien (GSFC/UMBC), A. Melandri (INAF-OAB), K. L. Page (U Leicester), D. M. Palmer (LANL), T. Sbarrato (INAF-OAB), B. Sbarufatti (PSU), M. H. Siegel (PSU) and A. Tohuvavohu (U Toronto) report on behalf of the Neil Gehrels Swift Observatory Team: At 17:04:36 on 2021-06-21 UT, the Swift Burst Alert Telescope (BAT) triggered on a burst from the Soft Gamma Repeater Swift J1555.2-5402 (trigger=1057131). Swift was already observing the source at that time. The BAT on-board calculated location is RA, Dec 238.812, -54.063 which is RA(J2000) = 15h 55m 15s Dec(J2000) = -54d 03' 45" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The immediately available BAT light curve showed a single high bin on the 64 ms timescale, consistent with the on-board trigger duration of 8 milliseconds for a single short spike. The peak count rate was ~1000 counts/sec (15-350 keV) on the 64 ms timescale, at ~0 sec after the trigger. Using promptly downlinked data we find an X-ray source with an enhanced position: RA, Dec 238.7871, -54.0615 which is equivalent to: RA(J2000) = 15h 55m 08.90s Dec(J2000) = -54d 03' 41.4" with an uncertainty of 2.0 arcseconds (radius, 90% containment), which is consistent with the position of Swift J1555.2-5402. This position may be improved as more data are received; the latest position is available at https://www.swift.ac.uk/sper. A power-law fit to a spectrum formed from promptly downlinked event data does not constrain the column density. UVOT took a finding chart exposures of 150 seconds with the white filter and 250 seconds with the U filter. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of the XRT error circle. Because of the density of catalogued stars, further analysis is required to report an upper limit for any afterglow in the sub-image. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18.0 mag. No correction has been made for the large, but uncertain, extinction expected. This source lies within the current (Sector 39) field-of-view of TESS camera 2. The current list of bursts from this source detected by BAT now stands at: 2021-06-03 09:45:46 GCN #30120 (discovery) 2021-06-05 23:52:04 ATEL #14690 2021-06-07 12:33:40 ATEL #14690 2021-06-13 06:35:22 not previously reported 2021-06-16 14:44:30 not previously reported 2021-06-21 17:04:36 This GCN //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 30711 SUBJECT: Swift detection of an outburst from SGR Swift J1555.2-5402 DATE: 21/08/25 07:13:16 GMT FROM: Phil Evans at U of Leicester M. G. Bernardini (INAF-OAB), P. D'Avanzo (INAF-OAB), P. A. Evans (U Leicester), J. A. Kennea (PSU), H. A. Krimm (NSF), A. Melandri (INAF-OAB), K. L. Page (U Leicester), T. Sakamoto (AGU), T. Sbarrato (INAF-OAB) and M. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift Observatory Team: At 06:53:27 UT, the Swift Burst Alert Telescope (BAT) triggered on a burst from the Soft Gamma-ray Repeater Swift J1555.2-5402 (trigger=1070298). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 238.836, -54.070 which is RA(J2000) = 15h 55m 21s Dec(J2000) = -54d 04' 12" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single structure with a duration of about 0.1 sec. The peak count rate was ~2700 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 06:54:47.7 UT, 80.4 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source with an enhanced position: RA, Dec 238.7859, -54.0617 which is equivalent to: RA(J2000) = 15h 55m 08.61s Dec(J2000) = -54d 03' 42.2" with an uncertainty of 1.9 arcseconds (radius, 90% containment). This location is 109 arcseconds from the BAT onboard position, within the BAT error circle. This position is consistent with the previously-reported position of Swift J1555.2-5402 (GCN 30122). This position may be improved as more data are received; the latest position is available at https://www.swift.ac.uk/sper. We cannot determine whether the source is fading at the present time. A power-law fit to a spectrum formed from promptly downlinked event data does not constrain the column density. UVOT took a finding chart exposure of 150 seconds with the White filter starting 85 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers none of the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18 mag. No correction has been made for the large, but uncertain, extinction expected. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 30796 SUBJECT: Swift detection of a burst from SGR Swift J1555.2-5402 DATE: 21/09/10 10:31:17 GMT FROM: David Palmer at LANL N. J. Klingler (GSFC/UMBC/CRESSTII), K. L. Page (U Leicester) and D. M. Palmer (LANL) report on behalf of the Neil Gehrels Swift Observatory Team: At 10:11:55 on 2021-09-10 UT, the Swift Burst Alert Telescope (BAT) triggered and located a burst from the Soft Gamma Repeater Swift J1555.2-5402 (trigger=1072706). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 238.773, -54.055 which is RA(J2000) = 15h 55m 05s Dec(J2000) = -54d 03' 16" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single high bin at the 64 ms timescale, consistent with the 4 ms trigger duration. The peak count rate on the 64 ms timescale was ~1300 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 10:13:14.4 UT, 78.8 seconds after the BAT trigger. Using promptly downlinked data we find an X-ray source with an enhanced position: RA, Dec 238.78912, -54.06236 which is equivalent to: RA(J2000) = 15h 55m 09.39s Dec(J2000) = -54d 03' 44.5" with an uncertainty of 1.9 arcseconds (radius, 90% containment). This location is 43 arcseconds from the BAT onboard position, within the BAT error circle, and consistent with the known position of Swift J1555.2-5402. This position may be improved as more data are received; the latest position is available at https://www.swift.ac.uk/sper. A power-law fit to a spectrum formed from promptly downlinked event data does not constrain the column density. UVOT took a finding chart exposure of 150 seconds with the White filter starting 82 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18 mag. No correction has been made for the large, but uncertain, extinction expected.