Fig. 1. Flow chart of algorithm for screening navigation stars

Fig. 2. Uniformly distributed random vector samples in celestial sphere

Fig. 3. Relationship among circular FOV, tangent longitude and optic declination

Fig. 4. Spherical area near optical axis

Fig. 5. Flow chart for screening bright stars

Fig. 6. Schematic of FOV radius of peripheral circle of sensor

Fig. 7. Probability distribution of number of stars in FOV. (a) After screening limiting star magnitudes; (b) after eliminating dark stars from small angular distance star pairs; (c) after screening bright stars from circular FOV

Fig. 8. Distribution of stars near optical axis. (a) After screening limiting star magnitudes; (b) after eliminating dark stars from small angular distance star pairs; (c) after screening bright stars from circular FOV