SGP4 Orbit Propagator with GUI

Determines visibility times from observer location for specified period. LLA and KML output.

Main function: OrbProp.m
NOTE: 1. Output generated by this program has not been validated, other than ensuring close agreement with AGI STK results. Prior to MAR 2018, expired Earth Orbit Parameters (EOP) were used for xp, yp, LOD, etc. This incurred slight variation from STK results (~0-30s offset). The program now downloads EOP data automatically from the internet, or allows selection of an EOP file the user may have.
2. Mapping toolbox and external program needed to execute distance, elevation, reckon, and azimuth functions; and plot LLA ground tracks.
This script runs the SGP4 propagator using the manual method, afspc, with
WGS72 ellipsoid. SGP4 output in ManualOut.out is transformed from TEME
to ECEF. The transformation teme2ecef is executed for each line of output in ManualOutput.out using time parameters for that iteration.
Input: TLE, UTC start, UTC stop, observer location, sector parameters. TLE input is a single two line file.
Output:
1. Access_Summary.txt: Summary of visibility times from observer's location, with az/el/slantrange
2. Access_Transit.txt: Used for plotting ground tracks for passes in Access_Summary.txt. Only visibility periods are included. Format: line number, lat, lon, alt (m geodetic), el(deg), az(degT), timevector
3. LLA_Transit.txt: Used for plotting ENTIRE ground track for period specified in the GUI. Format: line number, lat, lon, alt (m geodetic), timevector
4. PolarPlot.png: Az-El polar plot of passes in Access_Summary.txt
5. KML_Transit_Altitude.kml: Plot orbit at altitude for entire period in Google Earth
6. KML_Transit_GroundTrack.kml: Plot orbit ground track for entire period in Google Earth
--External program using mapping toolbox required for plotting ground tracks.
--A sector may be specified for the observer that constrains visibility windows.
--Geodetic horizon at observer location used for visibility when no sector specified.
Will appreciate any feedback/rating if difficulty is encountered or works as needed.