TITLE: GCN CIRCULAR NUMBER: 12359 SUBJECT: Swift detection of short bursts from PSR J1647-4552 DATE: 11/09/19 21:39:00 GMT FROM: David Burrows at PSU/Swift W. H. Baumgartner (GSFC/UMBC), D. N. Burrows (PSU), J. R. Cummings (NASA/UMBC), N. Gehrels (NASA/GSFC), C. Gronwall (PSU), S. T. Holland (CRESST/USRA/GSFC), J. A. Kennea (PSU), V. Mangano (INAF-IASFPA), C. B. Markwardt (NASA/GSFC), F. E. Marshall (NASA/GSFC), J. L. Racusin (NASA/GSFC), B. Sbarufatti (INAF-OAB/IASFPA), E. Sonbas (GSFC/USRA/Adiyaman Univ.) and T. N. Ukwatta (MSU) report on behalf of the Swift Team: At 21:16:11 UT, the Swift Burst Alert Telescope (BAT) triggered and located PSR J1647-4552 (trigger=503525). Swift slewed immediately to the position. Approximately ten minutes later (21:25:44 UT), BAT triggered again on same position (trigger=503526). The first BAT on-board calculated location is RA, Dec 251.752, -45.843 which is RA(J2000) = 16h 47m 00s Dec(J2000) = -45d 50' 33" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve of the first trigger (503525) showed a single-peaked structure with a duration of about 0.25 sec. The peak count rate was ~2500 counts/sec (15-350 keV), at ~0 sec after the trigger. The second burst had a similar burst intensity and time profile. The XRT began observing the field at 21:17:07.5 UT, 56.0 seconds after the BAT trigger. Using promptly downlinked data we find an X-ray source located at RA, Dec 251.79387, -45.87095 which is equivalent to: RA(J2000) = 16h 47m 10.53s Dec(J2000) = -45d 52' 15.4" with an uncertainty of 3.9 arcseconds (radius, 90% containment). This location is 145 arcseconds from the BAT onboard position, within the BAT error circle. This position may be improved as more data are received; the latest position is available at http://www.swift.ac.uk/sper. This position is 3.5 arcseconds from that of a known X-ray source: CXOU J164710.2-455216/PSR J1647-4552, a known magnetar (e.g. Woods et al., 2011, ApJ, 726, 37). A power-law fit to a spectrum formed from promptly downlinked event data gives a column density in excess of the Galactic value (1.88 x 10^22 cm^-2, Kalberla et al. 2005), with an excess column of 2.5 (+2.00/-1.60) x 10^22 cm^-2 (90% confidence). UVOT took a finding chart exposure of 150 seconds with the White filter starting 60 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. No correction has been made for the large, but uncertain extinction expected. It appears that this PSR is entering an SGR-like phase of activity.