TITLE: GCN CIRCULAR NUMBER: 5687 SUBJECT: IGR J08408-4503 (= V* LM Vel): Swift detection of a transient DATE: 06/10/04 15:47:29 GMT FROM: David Palmer at LANL H. Ziaeepour (UCL-MSSL), D. N. Burrows (PSU), S. Campana (INAF-OAB), J. R. Cummings (NASA/UMBC), O. Godet (U Leicester), C. Guidorzi (Univ Bicocca&INAF-OAB), V. Mangano (INAF-IASFPA), S. R. Oates (UCL-MSSL), C. Pagani (PSU), K. L. Page (U Leicester), D. M. Palmer (LANL), P. Romano (INAF-OAB), M. Stamatikos (NASA/ORAU), R. L. C. Starling (U Leicester) and E. Troja (INAF-IASFPA) report on behalf of the Swift Team: Beginning at 14:45:42 UT, the Swift Burst Alert Telescope (BAT) triggered and located a point source in a 27 minute image. Swift slewed immediately to the source at the location of the known gamma-ray transient IGR J08408-4503 (ATel 813; Gotz et al.) = V* LM Vel (ATel 818; Kennea et al.). The BAT on-board calculated location is RA,Dec 130.214, -45.063 {08h 40m 51s, -45d 03' 44"} (J2000) with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). As is typical for long image triggers, the BAT light curve shows no obvious variation attributable to the source. The XRT began observing the field at 15:17:07 UT, 1885 seconds after the BAT trigger (which is at the beginning of the 27 minute discovery image). XRT found a bright X-ray source located at RA(J2000) = 08h 40m 47.3s, Dec(J2000) = -45d 03' 29.5", with an estimated uncertainty of about 8 arcseconds (90% confidence radius, including boresight uncertainties). This location is 46 arcseconds from the BAT on-board position, within the BAT error circle. It is 5.2 arcseconds from the pulsating star V* LM Vel. The initial flux in the 2.5s image was about 1e-9 erg/cm2/s (0.2-10 keV). No obvious variability is seen in the quick-look light curve. Due to the presence of bright stars in the field of view, the UVOT was unable to observe.