TITLE: GCN CIRCULAR NUMBER: 23686 SUBJECT: GRB 190114B: Swift detection of a burst DATE: 19/01/14 19:48:11 GMT FROM: Amy Lien at GSFC M. H. Siegel (PSU), D. N. Burrows (PSU), J.D. Gropp (PSU), J. A. Kennea (PSU), N. J. Klingler (PSU), H. A. Krimm (NSF/USRA), N. P. M. Kuin (UCL-MSSL), S. J. LaPorte (PSU), A. Y. Lien (GSFC/UMBC), M. J. Moss (George Washington University), K. L. Page (U Leicester), B. Sbarufatti (PSU) and A. Tohuvavohu (PSU) report on behalf of the Neil Gehrels Swift Observatory Team: At 19:31:12 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 190114B (trigger=883818). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 174.883, +18.877 which is RA(J2000) = 11h 39m 32s Dec(J2000) = +18d 52' 36" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a weak pulse with a duration of about 20 sec. Also, there is a possible precursor at ~T-75 s. The peak count rate was ~800 counts/sec (15-350 keV), at ~4 sec after the trigger. The XRT began observing the field at 19:33:49.6 UT, 157.5 seconds after the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued X-ray source located at RA, Dec 174.87349, 18.89230 which is equivalent to: RA(J2000) = 11h 39m 29.64s Dec(J2000) = +18d 53' 32.3" with an uncertainty of 3.7 arcseconds (radius, 90% containment). This location is 63 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. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density consistent with the Galactic value of 1.75 x 10^20 cm^-2 (Willingale et al. 2013). UVOT took a finding chart exposure of 250 seconds with the U filter starting 157 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 19.2 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 18.0 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.02. Burst Advocate for this burst is M. H. Siegel (siegel AT swift.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.)