(25) Satellite Orbit Predicting using a pocket calculator

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An extract from 73 (magazine) August 1976, Satellite Orbit Predicting - - using a pocket calculator, pgs 113-114

A computer program has been written for the HP 25 pocket calculator, which is the new programmable calculator made by Hewlett Packard. The calculator is currently selling for around $180, and is an absolutely amazing little device which is fully programmable up to 49 steps. Programming is done in the same way a normal calculation is performed so that it is not necessary to study BASIC or FORTRAN 4 programming in order to program the device …
In the program shown here it is possible to just punch in the date of the month, such as the number "3" for the third of April, and then by pressing the program "run" button, get the pass number, the equatorial crossing time for that date, and the degrees west that the satellite crosses the equator …
After entering the program into the HP 25 , also enter the satellite constants in the program memory shown as the "registers" 0-7. It then becomes obvious that the constants for any of the Oscar or NOAA satellites may be entered to give the desired orbit information …
The program here is particularly useful for tabulating a full month's orbits for a particular satellite. Since the passes for each day occur about the same time, it is only necessary to know about the first pass of each day, and the other passes can be found through simple calculation or by substituting the pass number in the second half of the program.

simple & direct, enjoy.

BEST!
Satellite