//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 27696 SUBJECT: Swift Detection of a burst from SGR Swift J1818.0-1607 DATE: 20/05/06 17:55:55 GMT FROM: Scott Barthelmy at NASA/GSFC S. D. Barthelmy (GSFC), J.D. Gropp (PSU), J. A. Kennea (PSU), N. P. M. Kuin (UCL-MSSL), S. Laha (GSFC/UMBC/CRESST), F. E. Marshall (NASA/GSFC), M. J. Moss (GWU), K. L. Page (U Leicester), D. M. Palmer (LANL), B. Sbarufatti (PSU), M. H. Siegel (PSU) and A. Tohuvavohu (U Toronto) report on behalf of the Neil Gehrels Swift Observatory Team: At 17:36:50 UT, the Swift Burst Alert Telescope (BAT) triggered on Swift J1818.0-1607 (trigger=969823). Swift slewed immediately to the source. The BAT on-board calculated location is RA, Dec 274.498, -16.152, which is RA(J2000) = 18h 18m 00s Dec(J2000) = -16d 09' 06" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a single spike with a duration of about 0.3 sec. The peak count rate was ~1200 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 17:37:52.5 UT, 62.6 seconds after the BAT trigger. Using promptly downlinked data we find an X-ray source with an enhanced position: RA, Dec 274.5008, -16.1312 which is equivalent to: RA(J2000) = 18h 18m 00.18s Dec(J2000) = -16d 07' 52.3" with an uncertainty of 3.6 arcseconds (radius, 90% containment). This location is 75 arcseconds from the BAT onboard position, within the BAT error circle, and consistent with the known position of Swift J1818.0-1607. 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 gives a column density consistent with the Galactic value of 1.35 x 10^22 cm^-2 (Willingale et al. 2013). UVOT took a finding chart exposure of 150 seconds with the White filter starting 65 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. This source was first reported on 2020 March 12 (GCN #27373; Evans et al.) Since then it has been monitored every 3-7 days with Swift follow-up observations. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 27746 SUBJECT: Swift Detection of a burst from SGR Swift J1818.0-1607 DATE: 20/05/16 15:21:15 GMT FROM: David Palmer at LANL C. Gronwall (PSU), J.D. Gropp (PSU), J. A. Kennea (PSU), S. Laha (GSFC/UMBC/CRESST), A. Y. Lien (GSFC/UMBC), F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester) and D. M. Palmer (LANL) report on behalf of the Neil Gehrels Swift Observatory Team: At 15:03:28 UT, the Swift Burst Alert Telescope (BAT) triggered and located a burst from Soft Gamma Repeater SGR Swift J1818.0-1607 (trigger=972614). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 274.550, -16.193 which is RA(J2000) = 18h 18m 12s Dec(J2000) = -16d 11' 32" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single peak structure with a duration of about 100 ms. The peak count rate was ~1000 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 15:04:27.5 UT, 59.0 seconds after the BAT trigger. Using promptly downlinked data we find an X-ray source with an enhanced position: RA, Dec 274.5010, -16.1314 which is equivalent to: RA(J2000) = 18h 18m 00.23s Dec(J2000) = -16d 07' 53.0" with an uncertainty of 3.0 arcseconds (radius, 90% containment). This location is 279 arcseconds from the BAT onboard position, consistent with the known position of Swift J1818.0-1607. 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 gives a column density consistent with the Galactic value of 1.35 x 10^22 cm^-2 (Willingale et al. 2013). UVOT took a finding chart exposure of 150 seconds with the White filter starting 62 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 8'x8' region for the list of sources generated on-board covers none of the XRT error circle. No correction has been made for the large, but uncertain, extinction expected. Swift is currently monitoring this source every 3 days under a ToO program. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 28055 SUBJECT: Trigger 980513: Swift detection of SGR Swift J1818.0-1607 DATE: 20/07/02 07:41:35 GMT FROM: Kim Page at U.of Leicester M. G. Bernardini (INAF-OAB), P. D'Avanzo (INAF-OAB), N. J. Klingler (PSU), A. Y. Lien (GSFC/UMBC), A. Melandri (INAF-OAB), K. L. Page (U Leicester), D. M. Palmer (LANL) and T. Sbarrato (INAF-OAB) report on behalf of the Neil Gehrels Swift Observatory Team: At 07:09:38 UT on 2020-07-02, the Swift Burst Alert Telescope (BAT) triggered and located a burst from Soft Gamma Repeater SGR Swift J1818.0-1607 (trigger=980513). Swift slewed immediately to the source. The BAT on-board calculated location is RA, Dec 274.471, -16.167 which is RA(J2000) = 18h 17m 53s Dec(J2000) = -16d 09' 59" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single-peaked structure with a duration of about 100 ms. The peak count rate was ~3000 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 07:11:03.2 UT, 84.4 seconds after the BAT trigger. Using promptly downlinked data we find an X-ray source with an enhanced position: RA, Dec 274.5017, -16.1317 which is equivalent to: RA(J2000) = 18h 18m 00.40s Dec(J2000) = -16d 07' 54.2" with an uncertainty of 3.0 arcseconds (radius, 90% containment). This location is 165 arcseconds from the BAT onboard position, within the BAT error circle, and consistent with the catalogued position of SGR Swift J1818.0-1607. 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 87 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 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. This is the fourth time Swift has triggered on SGR Swift J1818.0-1607; with 5 additional burst detections that did not reach the level needed for a burst response. These detections were: 2020-02-28T22:19:32 2020-03-12T21:16:47 GCN 27373 2020-04-13T19:34:18 2020-05-06T17:36:50 GCN 27696 2020-05-16T15:03:28 GCN 27746 2020-05-17T14:29:54 2020-05-25T20:23:45 2020-06-01T16:52:09