Fig. 1. Observations over the Southeast Pacific Ocean on January 22, 2017. (a) Imaging of the first channel; (b) frequency distribution of DN values

Fig. 2. Average results of 71 frames observations data on the 13th channel on January 25, 2017. (a) Grayscale map of the 13th channel; (b) row distribution of mean DN values; (c) column distribution of mean DN values

Fig. 3. Comparison of daytime and nighttime dark current characteristics. (a) Horizontal characteristics; (b) vertical characteristics

Fig. 4. Row average diagram of the first channel on February 2, 2018

Fig. 5. Average results of 70 frames data for each channel on February 2, 2018. (a) Distribution of mean DN values; (b) distribution of maximum row average values; (c) distribution of minimum row average values

Fig. 6. Column average diagram of the first channel on February 2, 2018

Fig. 7. Dark current distribution of MAI CCD from October 2016 to February 2018. (a) Average DN value as a function of time; (b) average DN value of "bright points" as a function of time; (c) average DN value of "dark points" as a function of time

Fig. 8. Comparison of the data before and after the correction of the "bad point" of the first channel on February 2, 2018. (a) Before correction; (b) after correction

Fig. 9. Comparison of the data before and after the correction of the first channel on February 2, 2018. (a) Average of row before the horizontal correction; (b) average of row after horizontal correction; (c) average of column before vertical correction; (d) average of column after vertical correction

Fig. 10. Correction results of observation data of the first channel on February 2, 2018. (a) Before correction; (b) after overall correction