TITLE: GCN CIRCULAR NUMBER: 43435 SUBJECT: Swift triggered on the HMXB 1A 1118-61 DATE: 26/01/17 06:59:18 GMT FROM: K.L. Page at U Leicester <klp5@leicester.ac.uk> R. Gupta (NASA GSFC) and K. L. Page (U Leicester) report on behalf of the Neil Gehrels Swift Observatory Team: At 06:28:58 UT, the Swift Burst Alert Telescope (BAT) triggered and located the HMXB 1A 1118-61 (trigger 1441823). Swift slewed soon after the event. The BAT on-board calculated location is RA, Dec 170.183, -61.905 which is RA(J2000) = 11h 20m 44s Dec(J2000) = -61d 54' 17" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a complex structure. This is an image-triggered event. The XRT began observing the field at 06:35:17.6 UT, 378.7 seconds after the BAT trigger. XRT found a bright X-ray source located at RA, Dec 170.2403, -61.9170 which is equivalent to: RA(J2000) = 11h 20m 57.67s Dec(J2000) = -61d 55' 01.2" with an uncertainty of 5.5 arcseconds (radius, 90% containment). This location is 106 arcseconds from the BAT onboard position, within the BAT error circle. This position is 4.3 arcseconds from a known X-ray source: LSXPS J112057.1-615459. This source is in the Swift XRT LSXPS catalogue with a mean 0.3-10 keV count-rate of 0.2537 +/- 0.0012 ct/sec; see https://www.swift.ac.uk/LSXPS/LSXPS%20J112057.1-615459 for details of these previous observations. No event data are yet available to determine the column density using X-ray spectroscopy. This trigger occurred just as Swift was exiting the SAA, so it is not clear at this time whether the source has actually brightened, or if the trigger was caused by the enhanced particle background. View this GCN Circular online at https://gcn.nasa.gov/circulars/43435. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...