SUN RISING/SETTING TIME COMPUTING APPARATUS

摘要

PURPOSE:To compute and display sun rising/setting time at any location by providing an electronic wrist watch with a memory means for position/date data and an arithmetic program and a computing means for executing the arithmetic program. CONSTITUTION:A city stored in a city register C and a date stored in a current time register T are converted into GMT to be stored into a register Z0 for computation. From this data, a calculation variable alpha(number of days to an input date from January 1st) is calculated to be stored into a register Z1. A calculation variable (s) is calculated by a specified formula to be stored into a register Z2. Based on the variable alpha, equation of time KJS is calculated to be stored into a register Z3. Median time (local mean solar time) is calculated from longitude, the GMT time difference and KJS to be stored into a register Z4. An apparent declination delta of the sun is calculated from the variable (s) to be stored into a register Z5. A sun rising/setting time demand number is calculated from a latitude phi and the apparent declination delta to be stored into a register Z6. Thus, an rising/setting time is determined by sun rising/setting time = median time - (+) sun rising/setting time demand number.