The calculators I programmed this code on originally (HP 28S, HP48G and Casio fx7000G) were first introduced in the 1980s, and they had way much more horsepower then than I needed to perform this calculation. Now that they are old and can’t be replaced, I just want to substitute them with something with just enough capability to do the job and that will cost under $50. (Under $20, if possible!) It also should be a device I don’t have to spend more than a few minutes learning how to program.

I don’t need a high powered programmable and graphics calculator that has built in functions, statistics, calculus, DEs, matrices and fancy font and display options that will set me back a couple of hundred simoleons. All I want is something that can do this:

Input Data Prompts
“SEX”? => O
“GHA”? => G
“DEC”? => D
“LAT”? => T
“LON”? => N

Calculate the Local Hour Angle
G+N => L

Correct the LHA
If L<0 then (L+360) => L
If L>360 then (L-360) => L

Calculate altitude
sinD => S
cosD x cosL => C,
S x sinT => X
C x cosT => Y
sin-1(X+Y) => H

Calculate azimuth
S x cosT => X
C x sinT => Y
(X-Y)/cosH => X
If X>1 then 1 => X
If X< -1 then -1 => X
cos-1(X) => A
(360-A) => Z
If L>180 then A => Z

Display intercept and azimuth
“INT”
(O-H) x 60 => I >
“AZM”
Z >

I can do this manually on a non-programmable $12 calculator, but it takes about 20 minutes and it is very easy to get lost or make a mistake. By programming it, I just need to input 5 angles and I get one line of position immediately.