To locate when ISS passes above you, use these Transit-finder Heavens above N2yo Celestrak SubGP is very accurate, and provides TLE in 6 hour segments, and you can use simulator to visualise ISS ID: 25544 CSS TianHe Norad ID: 48274 Beebottle using celestrak data and python ESA should be most accurate, but only shows + or - 1.5 hours. so BE prepared to re-position the latest path ( takes a few seconds to refresh) spotthestation for Hong Kong trajectory data Kibo forecast for Japan area only Chinese Space Station, Tiangong 3 Aug 09:04 CSS Sun transit over Hong Kong, quite BIG difference in predictions, so don't have high hope on this rare event Orekit and forum talking about ISS pass in perl Sourceforge by Ed Morana