P_r of 252P from the IRSF data (Table 1) as a function of the wavelength. The numbers on the left side of the data indicate the order of the observation epochs (1: March 04, 2: March 09, 3: March 11, 4: March 12, 5: March 13, 6: March 14, and 7: March 15), and the numbers on the right side are the phase angles of the corresponding epochs. Red on the fourth epoch (March 12) denotes the day when the comet shows the maximum NIR brightness (open circles in Fig. 1a).