ISSTracker supports the ISS (International Space Station / Zarya), Hubble Space Telescope, and any other satellite (out of hundreds listed at CelesTrak.com) defined by the user.
The ISS is an especially interesting object for sky watchers because (in favorable conditions) its visual brightness reaches -4 mag., i.e. much brighter than the brightest star Sirius, and often even brighter than Venus (even by 8 to 16 times when it produces flares as sunlight glints off its reflective surfaces). So it often becomes the third brightest object in our sky, after the Sun and the Moon. The ISS orbits the Earth at very high speed so it passes over one's location many times a day, but it is visible only in certain conditions: when the sky is dark enough not to outshine it, and the Sun is not too low under the horizon for its light to reach the ISS and get reflected by it. This means that the ISS can be seen only shortly after the sunset or before the sunrise. And it only takes several minutes (usually between 1 and 10) for it to cross the sky and disappear.
This program predicts visible passes of ISS, HST and any other satellite. It calculates and displays dates and times of approach, visibility duration, and azimuths and elevations of approach, transit and departure (i.e. where the satellite becomes visible, where it disappears and what is its higest elevation).
For each satellite the program shows (and updates every 3 seconds) on Nokia Maps its current position and where it will be within the next hour (in 5-minute steps). The map can be zoomed in/out from world map to street level, and map imagery can be selected from street, terrain and satellite.
In addition to ISS and HST, the user can add any other satellite out of hundreds of satellites listed at CelesTrak.com. Adding a satellite only takes entering its name and the name of file containing its orbit data (as listed on CelesTrak).
ISSTracker automatically downloads and saves current orbit data (TLE) from CelesTrak, which assures the highest precision.
User location can be obtained from the GPS receiver or entered manually.