From a set of two-line elements of the ISS (or any low-earth orbit satellite), inspect will calculate the latitude, longitude, altitude, SAA passes and night passes of the ISS. The duration of the prediction as well as the time step is settable by the user.
inspect use the SGP4 library written by D. Vallado in C++ to process the given TLE.
inspect can only support the following TLE format (the first line being optional. But if present should be 24 characters long)
ISS (ZARYA)
1 25544U 98067A 18304.35926896 .00001207 00000-0 25703-4 0 9995
2 25544 51.6420 60.1332 0004268 356.0118 61.1534 15.53880871139693
the input file can be read by inspect from a local file or a remote file available on a http/https server.
the output of inspect consists of a csv file. The columns of the file are:
- datetime (YYYY-mm-dd HH:MM:SS.ssssss)
- modified julian day
- altitude (kilometer)
- latitude (degree or DMS)
- longitude (degree or DMS)
- eclipse (1: night, 0: day)
- crossing (1: crossing, 0: no crossing)
- TLE epoch (not printed when output is pipe separated)
inspect can give the position of a satellite in three different way (mutually exclusive):
- geocentric: the latitude, longitude and altitude are calculated from the centre of the earth.
- geodetic: the latitude, longitude and altitude are calculated above an ellipsoidal surface of the earth.
- teme/eci: the latitude, longitude and altitude are calculated from the centre of the earth. The main difference is that, in this system, the values are computed in an inertial system that do not rotate with the earth. These values are the outcome of the SGP4 propagator used by inspect and are used the computed the latitude, longitude in the geodetic or geocentric system.
$ inspect [options] <file|url>
-b DATE start date
-c COORD coordinate system used (geocentric, geodetic, teme/eci)
-d TIME TIME over which calculate the predicted trajectory
-f FORMAT print predicted trajectory in FORMAT (csv, pipe, json, xml)
-i TIME TIME between two points on the predicted trajectory
-r AREA check if the predicted trajectory crossed the given AREA
-s SID satellite identifier
-t DIR store a TLE fetched from a remote server in DIR
-w FILE write predicted trajectory in FILE (default to stdout)
-bstar LIMIT B-STAR drag coefficient limit
-360 longitude are given in range of [0:360[ instead of ]-180:180[
-dms convert latitude and longitude to DD°MIN'SEC'' format
-config load settings from a configuration file
-version print inspect version and exit
-info print info about the given TLE
-help print this message and exit