TITLE: GCN CIRCULAR NUMBER: 17716 SUBJECT: Confirmation that Swift trigger 638217 is not an astrophysical source DATE: 15/04/17 14:49:12 GMT FROM: Hans Krimm at NASA-GSFC H. A. Krimm (CRESST/GSFC/USRA) and B. Sbarufatti (INAF-OAB/PSU) report on behalf of the Swift Team: We conclude that Swift trigger #638217 (Gehrels, et al., GCN Circ. 17712) was the result of noise fluctuations and is not due to a GRB or other astrophysical event. We have analyzed the BAT data set from T-239 to T+440 sec from the recent telemetry downlink. We find that there is no sign of significant emission from the trigger location at any point in this interval. XRT observations in Photon Counting mode data started 152 s after the BAT trigger. In 1.9 ks of PC data no source is detected inside the BAT error circle. The three sigma upper limit is 9.5e-3 counts/second.