To get the CZML file displaying the orbits of the satellites with NORAD catalog id: 39159 (Proba-V), 39634 (SENTINEL-1A)
Between the data range: 2018-02-26 15:00:00 and 2018-02-26 15:00:00
This can then be saved as a .czml and drag and dropped into the Cesium Viewer to visualise the orbit on your own site
To get a list of overpasses for the satellite with NORAD catalog id: 27386 (ENVISAT)
Between the date range: 2018-02-22 22:35:00 and 2018-02-23 22:35:00
For a location in Dublin with lat/lon: 53.3013018, -6.5379840
The data is returned in JSON format, the most important part of the results is the "rise_time" and the "set_time" of each overpass, which tell you when the satellite becomes visible from the ground location, i.e. when it rises over the horizon, and when it stop being visible, i.e. when it sets below the horizon.
The czml data for each overpass is stored in the response object under the key "czml_data", this can be copied into a .czml file and visualised in the Cesium viewer.
For your own program you can edit the parameters for the satellite, time and location you interested in.
Satellites available for API: Satellite List