data for each hit received. Each hit contains 14 values, including time, position, beam number, power, SNR, channel number, and frequency. Telescope information can be stored in header fields. This format is known as ETFITS and has been utilized by recent SERENDIP projects.

Data processing\[sec:birdies\]
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In order to verify the validity of our pipeline, some artificial candidate targets, called “birdies", are added to our data. We randomly generate some signals along the moving trajectory of beam one, and if other beams go through the same position, we add more signals with the same frequency into that beam. Birdies generated are shown in Figure \[fig:12\], which contains 20 groups and 294 signals.

After adding birdies, we use Nebula and the KNN pipeline to remove the RFI. 99.9063$\%$ of hits are removed by our pipeline while only 5.1020$\%$ of birdies were removed. Note that we make a temporary change to Nebula. To get an ideal velocity, we first remove zone RFI and then remove other kinds of RFI simultaneously. Details are shown in Table \[tab:5\]. Most of the RFI in FAST are removed by the zone RFI algorithm. In the future, we will try to find the source of zone RFI 