A stepped afterglow light curve of GRB 171205A

In this work we study the afterglow light curve of GRB 171205A; this long burst was discovered by the Burst Alert Telescope (BAT) on board Neil Gehrels Swift and Konus-Wind, respectively. The X-Ray Telescope (XRT) began observing the burst at 144.7 seconds and ended at 6748135.04 seconds after the BAT trigger. The whole contour of the XRT light curve of GRB 171205A consists of three parts, as follows: steep decay, shallow decay and normal decay. Margutti wrote two proposals for two observations of this source using Chandra satellites on February 14 and June 29, 2018. Combined with the Chandra data, a detailed analysis of the normal decay reveals that there are four steps in the substructure. This phenomenon is unusual. It occurs in the late stages and does not undergo intense light changes. so it is not caused by the central engine, but may be caused by the external environment.