TITLE: GCN CIRCULAR NUMBER: 24147 SUBJECT: GRB 190422A: Swift detection of a burst DATE: 19/04/22 23:15:41 GMT FROM: David Palmer at LANL M. J. Moss (George Washington University), S. D. Barthelmy (GSFC), J.D. Gropp (PSU), J. A. Kennea (PSU), N. J. Klingler (PSU), N. P. M. Kuin (UCL-MSSL), A. Y. Lien (GSFC/UMBC), F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester), M. H. Siegel (PSU) and A. Tohuvavohu (PSU) report on behalf of the Neil Gehrels Swift Observatory Team: At 22:55:29 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 190422A (trigger=899979). Swift did not slew until ~T+8 min due to an observing constraint. The BAT on-board calculated location is RA, Dec 182.124, -60.238 which is RA(J2000) = 12h 08m 30s Dec(J2000) = -60d 14' 15" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a complex structure with a duration of at least 220 sec, where data are currently available. The peak count rate based on the available data was ~2000 counts/sec (15-350 keV), at ~175 sec after the trigger. The XRT began observing the field at 23:04:18.5 UT, 529.3 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 182.03650, -60.22311 which is equivalent to: RA(J2000) = 12h 08m 08.76s Dec(J2000) = -60d 13' 23.2" with an uncertainty of 3.8 arcseconds (radius, 90% containment). This location is 165 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. 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 in excess of the Galactic value (8.59 x 10^21 cm^-2, Willingale et al. 2013), with an excess column of 1.1 (+1.25/-0.89) x 10^22 cm^-2 (90% confidence). UVOT took a finding chart exposure of 150 seconds with the White filter starting 531 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 source lies within the current (Sector 11) field-of-view of TESS camera 2. Burst Advocate for this burst is M. J. Moss (mikejmoss3 AT gmail.com). 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/)