W1-W2 distribution with W1 about the 359 stars correlated with 2MASS. The positions of the 359 stars cross-match with 2MASS on the W 1 - W2 vs. W1 colour–magnitude diagram. The sky-blue circle marks the 332 matches within 5″, the orange triangle and red square represent the seven stars with WISE counterparts and 18 stars without WISE counterparts when enlarging the match radius. We note that there are two binary star systems matched to the same 2MASS counterpart, so they are treated as one object which cannot seen from this plot.