TITLE: GCN CIRCULAR NUMBER: 33202 SUBJECT: Trigger 1150107: Swift detection of LS V +44 17 DATE: 23/01/21 06:07:32 GMT FROM: Jamie Kennea at Penn State U J.D. Gropp (PSU), J. A. Kennea (PSU), N. J. Klingler (GSFC/UMBC/CRESSTII), A. Y. Lien (U Tampa) and D. M. Palmer (LANL) report on behalf of the Neil Gehrels Swift Observatory Team: At 05:44:17 UT, the Swift Burst Alert Telescope (BAT) triggered and located the known source LS V +44 17 (trigger=1150107). Swift slewed immediately to the location. The BAT on-board calculated location is RA, Dec 70.267, +44.525 which is RA(J2000) = 04h 41m 04s Dec(J2000) = +44d 31' 30" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). As is typical for an image trigger, the flux from the source is difficult to distinguish from background in the immediately available lightcurve. The XRT began observing the field at 05:46:13.8 UT, 116.5 seconds after the BAT trigger. XRT found a bright X-ray source located at RA, Dec 70.2493, 44.5309 which is equivalent to: RA(J2000) = 04h 40m 59.83s Dec(J2000) = +44d 31' 51.2" with an uncertainty of 5.0 arcseconds (radius, 90% containment). This location is 50 arcseconds from the BAT onboard position, within the BAT error circle. This position is 6.8 arcseconds from a known X-ray source: LS V +44 17. LS V +44 17 has been recently reported to be on the rise, e.g. ATEL #15868. The long term lightcurve can be seen on the BAT Transient Analysis page for this source and shows that the outburst is still increasing after an initial peak and decline. https://swift.gsfc.nasa.gov/results/transients/weak/LSVp4417/ (The bottom plot on that page shows the 2010 peak. The current outburst is the plot above it, shown in blue.)