ephem [ parameter=value ... ]
Parameters are: receiver_lat, receiver_lon, satellite, sensor, pass_date, pcap_time, time_step, printout.
ephem reports satellite subtrack information at discrete time steps for a user specified pass in the form of the elevation angle above the horizon relative to the receiver (antenna), azimuth angle from the north, latitude and longitude, and satellite orbital radius in kilometers.
This function does not require the specification of any input or output TeraScan datasets.
Latitude of the receiver (antenna).
See formats for specification of latitude and longitude formats. The default value is retrieved from the file last_location.
Longitude of the receiver (antenna).
See formats for specification of latitude and longitude formats. The default value is retrieved from the file last_location.
This is the name of the satellite in lower case.
There is no default.
This is the sensor name entered in lower case.
The default is avhrr.
This is the start date of the pass.
Any valid date is allowed, see formats. The default is today's date.
This time is used to select the satellite orbit. This can be any time, so long as the satellite is above the local horizon of the receiver for the time entered. A good choice for this time is the point of closest approach time from the pcap report.
Any valid time is allowed, see formats. There is no default value.
This is the time interval (in seconds) between subsequent reports of satellite position
Valid responses are [> 0]. The default value is 30.
Determines whether the output is sent to the hardcopy device or the screen.
Valid response are [yes or no]. The default is no.
This example prints out the subtrack information for a user specified pass. The pcap_time was selected from the times printed out in the pcap example.
[65]% ephem receiver_lat : char( 15) ? [32 50.47 N] receiver_lon : char( 15) ? [117 13.65 W] satellite : char( 11) ? noaa-11 sensor : char( 5) ? [avhrr] pass_date : char( 15) ? [92/01/27] 91/10/12 pcap_time : char( 15) ? 21:26:47 time_step : int ? [30] 60 printout : char( 3) ? [no] noaa-11 avhrr Ephemeris Receiver: 32 50.47 N, 117 13.65 W Page 1 Date Time Elevation Azimuth Latitude Longitude Radius 91/10/12 21:20:00 2.25 141.50 11 34.74 N 101 10.97 W 7221.97 91/10/12 21:21:00 6.15 138.40 15 5.60 N 102 1.24 W 7221.52 91/10/12 21:22:00 10.62 134.27 18 36.29 N 102 52.70 W 7221.09 91/10/12 21:23:00 15.82 128.52 22 6.77 N 103 45.67 W 7220.68 91/10/12 21:24:00 21.88 120.15 25 37.00 N 104 40.56 W 7220.30 91/10/12 21:25:00 28.50 107.49 29 6.90 N 105 37.84 W 7219.95 91/10/12 21:26:00 34.16 88.75 32 36.43 N 106 38.06 W 7219.64 91/10/12 21:27:00 35.79 65.09 36 5.52 N 107 41.92 W 7219.36 91/10/12 21:28:00 32.13 42.97 39 34.08 N 108 50.27 W 7219.12 91/10/12 21:29:00 25.80 26.98 43 2.02 N 110 4.21 W 7218.92 91/10/12 21:30:00 19.35 16.42 46 29.23 N 111 25.13 W 7218.77 91/10/12 21:31:00 13.68 9.38 49 55.55 N 112 54.93 W 7218.66 91/10/12 21:32:00 8.82 4.48 53 20.77 N 114 36.12 W 7218.61 91/10/12 21:33:00 4.62 0.94 56 44.60 N 116 32.22 W 7218.61 91/10/12 21:34:00 0.92 358.28 60 6.64 N 118 48.25 W 7218.66
sensorfile, orbdata, last_location.
avhrr, ols, xcapcon, etx, fastreg, master, orbit, pcap, passcover
Last Update: $Date: 1998/05/28 18:05:00 $