TITLE: GCN CIRCULAR NUMBER: 22695 SUBJECT: GRB 180510A: Swift detection of a burst DATE: 18/05/10 19:47:25 GMT FROM: Boris Sbarufatti at PSU J.D. Gropp (PSU), A. Deich (PSU), J. A. Kennea (PSU), S. J. LaPorte (PSU), A. Y. Lien (GSFC/UMBC), F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester), B. Sbarufatti (PSU), M. H. Siegel (PSU) and A. Tohuvavohu (PSU) report on behalf of the Neil Gehrels Swift Observatory Team: At 19:24:34 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 180510A (trigger=831810). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 276.318, -31.911 which is RA(J2000) = 18h 25m 16s Dec(J2000) = -31d 54' 38" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a multi-peaked structure with a duration of about 70 sec. The peak count rate was ~8000 counts/sec (15-350 keV), at ~5 sec after the trigger. The XRT began observing the field at 19:26:02.5 UT, 88.3 seconds after the BAT trigger. XRT found a bright, uncatalogued X-ray source located at RA, Dec 276.3303, -31.9069 which is equivalent to: RA(J2000) = +18h 25m 19.27s Dec(J2000) = -31d 54' 24.8" with an uncertainty of 5.5 arcseconds (radius, 90% containment). This location is 40 arcseconds from the BAT onboard position, within the BAT error circle. No event data are yet available to determine the column density using X-ray spectroscopy. The initial flux in the 2.5 s image was 1.09e-09 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 96 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. Because of the density of catalogued stars, further analysis is required to report an upper limit for any afterglow in the sub-image. Results from the list of sources generated on-board are not available at this time. No correction has been made for the expected extinction corresponding to E(B-V) of 0.26. Burst Advocate for this burst is J.D. Gropp (jdg44 AT psu.edu). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/too.html.)