C2A allows you to display the position of artificial satellites known through their orbital elements. This feature requires that the Python 3 environment is installed on your computer (see the section devoted the the Python 3 environment). The satellite orbital elements must be provided under the form of TLE files (Two-Line Elements) which are a standardized representation of orbital elements of Earth-orbiting objects. A TLE file is typically built as follows:
ISS (ZARYA)
1 25544U 98067A 17239.88691495 -.00096412 00000-0 -14750-2 0 9995
2 25544 51.6463 40.8901 0004596 191.5604 320.7288 15.53966142 72909
TIANGONG 1
1 37820U 11053A 17239.79886256 .00032157 00000-0 14884-3 0 9999
2 37820 42.7579 120.3608 0020095 233.3124 209.6570 15.82522929339302
AGGIESAT 4
1 41313U 98067HP 17239.82368257 .00029756 00000-0 18025-3 0 9993
2 41313 51.6408 354.0733 0003123 43.7984 316.3264 15.77298270 90223
NODES 2
1 41477U 98067HX 17239.75463142 .00180833 24153-4 42415-3 0 9998
2 41477 51.6227 347.9823 0006743 343.4760 16.6028 15.96510554 73443
NODES 1
1 41478U 98067HY 17239.71072624 .00155073 20511-4 39876-3 0 9995
2 41478 51.6269 349.2606 0006286 342.0274 18.0511 15.94882573 73423
Each declaration block is made of 3 lines, a first line with the artifical satellite name followed by 2 lines that contain the orbital elements. It is possible to insert blank lines between blocks but not within a block. It is important to update TLE files on a regular basis since orbital elements quickly change over time. Many Internet web sites provide TLE files for artificial satellites such as https://www.celestrak.com/NORAD/elements/.
Once a TLE file is locally available on your computer, it must be loaded in C2A. To do that, you must use the Artifical Satellite dialog box using the command Artificial Satellite from the File menu.
You can add TLE files using the button Add... The satellites from a TLE file will be displayed only if the check mark option on the left side of the TLE file path is checked. The button Remove allows you to remove the currently selected file from the list and the button Clear removes all the TLE files in the list. The button Edit... allows you to open the currently selected TLE file in a text editor (using the default Windows text editor or the text editor specified in the tab Misc of the Option dialog box).
Once a TLE file is loaded, you must make sure that the artificial satellite display in C2A's maps is activated. To do that, use the commande Other catalogues / Artificial Satellites from the Display menu or use the button Artificial Satellites in the main toolbar. You can also check the option Artificial Satellites from the SolSys tab in the Options dialog box.
It must be noted that most of the artificial satellites move at ahigh speed on the sky background and you must therefore accurately specify the date and time at which you want to perform the observation. When the current PC time is used for the current map, the satellite positions are automatically refreshed at regular intervals. This refresh time can be specified with the option "Refresh maps with artificial satellites every" in the Map tab of the Options dialog box:
