Meaning of OBSERVATION in English
( n. )
Specifically, the act of measuring, with suitable instruments, some magnitude, as the time of an occultation, with a clock; the right ascension of a star, with a transit instrument and clock; the sun's altitude, or the distance of the moon from a star, with a sextant; the temperature, with a thermometer, etc.
Webster's Revised Unabridged English Dictionary. Пересмотренный полный словарь английского языка Webster. 2012