they are associated with RFI features. Four groups of candidates with raw data background are shown in Figure \[fig:15\] and \[fig:16\]. We examine all of the candidates and find that most of them have an obvious connection to RFI features. This is unsurprising because our RFI removal algorithm cannot completely remove all RFI. The unremoved RFI events match roughly to our definition of candidate’s characteristics. Improvement of the RFI algorithm is an iterative process that we expect to continue as long as this system is used on FAST.

For the five hours data, we find two group candidates of interest which have no hits around them. These two group candidates are shown in Figure \[fig:16\]. The red group around 1055 MHz and 4280 seconds is called Group 1. The red group around 1055 MHz and 4430 seconds is called Group 2. We zoom into the two groups of candidates in Figure \[fig:17\]. Group 1 is in the top panel of the figure with 5 hits in the same frequency channel. Group 2 is in the bottom panel of the figure with 80 hits in six successive channels. Group 1 is all from beam 15, and the duration is about 5 