Other high-precision values are not derived from a coherent IAU system. A value of 9.460 536 207 × 10 m found in some modern sources is the product of a mean Gregorian year (365.2425 days or 31 556 952 s) and the defined speed of light (299 792 458 m/s). Another value, 9.460 528 405 × 10 m, is the product of the J1900.0 mean tropical year and the defined speed of light.