test

        theta = rotTelPos - rotSkyPos          

        ############ load star data catlog #####################            

        starcat='selection_20230517_concat.csv'

        ##starcat='selection_20230517_concat.csv'

        starcat='star_catlog'

        ##starcat='GaiaSource_675688-675713.csv'

        ####

        #df=df0.fillna(1000)

        #df2=df[ (df['phot_rp_mean_mag']>16)&(df['phot_bp_mean_mag']>16) & (df['phot_bp_mean_mag']<31) & (df['pmra']<100) & (df['phot_rp_mean_mag']<31)]

        #df2=df[ (df['umag']>16)&(df['zmag']>16) ]

        #df2.index = range(len(df2))      

        ## limit the filed of view to 600*600 arcsec^2 square zone;