Kepler's 2nd. Law

[twdeckard]

Greetings Ángel

Thank you for the kind words, remember, the program doesn't work yet. Candidly the best effort would be to scrap it and weld the TLE parser on the article that SlideRule posted.

The SATREG ASCII file is a list of variable mnemonics prefixed with a numerical type. Its a common pattern I used so that I can revisit an old program and have some hope of deciphering it. It is also why I squander precious registers on six character labels. I invariably have to scavenge those as I get to the limit of memory.

Here is the SATREG contents:

Code:

4^TMP
4^TMP
4^TMP
4^TMP        
4^SX
4^SY
4^SZ
4^OX
4^OY
4^OZ
4^VOx
4^VOy
4^VOz
4^RX
4^RY
4^RZ
4ELAPST
4CURORB
4OBJECT
1EPYEAR
2EPTIME
3INCLIN
2R.A.A.N
4ECCENT
2PERIGE
2MEANAN
3MMDOT1
3MMDOT2
4DECAYR
1ORBITN
6OBSLAT
6OBSLON
4LAMBDA
1SATRNG
4DOPPLR
6SATLAT
6SATLON
1AZIMUT
1ELEVAT
1OBSHGT
4MEANAT
4KD    
4KDP

The ISS ASCII file contains the two-line element (sometimes slang'd as a Kepler although it is not). They can be had from Celestrak or one of the other providers although NORAD is the source.

Code:

1 25544U 98067A   18071.70991576  .00002716  00000-0  48084-4 0  9995
2 25544  51.6420 139.6732 0001880 178.1916 325.8769 15.54223294103518

The MMDOT refers to the decay rate. There certainly isn't any MCODE in my vocabulary. I mixed in comments from the original BASIC program that inspired this effort. Maybe the comments looked like assembly. If it hurts my credibility, at one point, I was comparing output from a Commodore 64 to error check my '41.

Take care if hoping for some sensible output from the github repository. I had an ESD catastrophe during development and I am not sure it is even up to date. I only now have reconstituted all the keystrokes in the calculator and it does not even parse the TLE correctly. Most likely due to typos.

Even when working I only got as far as a correct ECF to ENU transformation. Everything else was wrong. Rather than simply "port" the BASIC I tried to go back to the actual coordinate transformations but it has gotten the better of me. I bought a "backup" HP41CX off of ebay and it had an Advantage module so I was looking for an excuse to do some matrix operations.

I will post something if I make any forward progress.

Best
Todd