We select clusters with narrow bandwidth and a duration less than few tens of seconds.

These two rules define the expected characteristics of extraterrestrial signals as they would appear during drift-scan sky survey observations. The final step is that we save all the candidates by location pixel. Pixels are defined to be small rectangles that divide the celestial sphere. All the candidates selected by the pipeline will be be saved by pixels in order to further analyze the candidate targets of the same sky position.

Analysis and results for FAST data {#sec:6}
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FAST data
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Our data were collected during a drift-scan survey performed by FAST during commissioning in July, 2019. To ensure beam health and data integrity, we employ a system health monitor. The monitor (Figure \[fig:10\]) shows a coarse (2048 point) power spectrum (with RMS deviation) for each of 19 beams in both polarization at each beam’s location in the focal array. We update the power spectrum and the RMS in the plot windows every five minutes to monitor beam health.

The data from each beam are saved into an FITS file separately. The size of each file is roughly one gigabyte and records a table of 