Pulsation properties of 294 confirmed Miras by OGLE compared with our results. Left panel a: directly compares the periods in the upper part; the dotted line marks the one-to-one relation. The lower part indicates the difference in periods as a function of the period found by OGLE. The star at P = 1858 d (log P = 3.26) in the top panel is located outside the plot at ΔPeriod = 216 d in the bottom panel. Middle panel b: compares the amplitude in the K band to that in the I band. The OGLE team defines amplitude as the minimum-to-maximum variation, while we use the traditional definition (see Eq. (1)). Stars with a are marked by a plus sign, and stars where the error on the K-band amplitude is larger than the amplitude are marked in red. The dotted line indicates the cut-off value of 0.1 mag we used to select the maximum number of known Miras from our sample. The solid line has a slope 0.5 to guide the eye. Right-hand panel c: relative error of the period determination against the period. Stars with a are marked by a plus sign, and stars where the error on the K-band amplitude is larger than the amplitude are marked in red. The dotted line indicates the cut-off value of 4% error on the period determination we used to select Miras from our sample.