Satgen 600 ISS Tracking by GM4IHJ (BID SGEN600) 2000-09-23 The International Space Station is now said to be ready for its first long stay crew. This will not actually occur until some time in November. Even then it will probably be a while, before Amateur Radio operation begins. But given the dearth of useful low earth orbit amsats, ISS and Mir , look like being the only platforms available for school , club and experimenter qsos, for several years. So perhaps this is a good time to begin tracking ISS. There are no radio signals from it at present. But over the next month of October 2000, given clear starry early evening skies, there will be some excellent visual passes in range of most northern hemisphere stations. Passes during which, ISS over flying a darkened earth, will reflect sunlight. Appearing as a bright star moving from west to east across the sky. High elevation pases should be easy to see. But passes which never come more than 10 degrees above your station horizon are likely to be lost in haze. Equally important, be aware that you only see ISS in reflected sunlight, it is not itself lit up. So as orbits get later and later after sunset , the illuminated part of ISS passage across your sky gets shorter and shorter. You always see the start of an illuminated pass when it gets 10 degrees or so above your horizon, but as it comes eastward across your sky , you lose it. Often when it is only half way across your sky, because ISS is no longer seeing the sun, now increasingly far to its west. All is not lost at these times when ISS is " eclipsed " by the earth. As the cut out begins , you are seeing ISS via sunlight which is skimming the horizon far to your west. Coming through an atmosphere which may be cloudy, dusty or misty. So do not be surprised if ISS changes colour , or its light switches on and off once or twice before finally disappearing. You are just taking a long range view of the weather far to the west. For really early birds , there is a second shot at ISS tracking in the early morning pre dawn , when orbit pass times are suitable. But be warned you do not see the ISS as it comes above your western horizon. You have to wait until it can see the pre dawn sun, far to your east. So it will travel unseen across part of your western sky. Suddenly becoming visible , perhaps with a bit of horizon flickering, when it gets far enough east to see the sun. From where you should be able to follow it all the way down to within 10 degrees or so of the eastern horizon before you lose it in the haze. Please note that what is said here about ISS, applies equally to Mir. Though the actually operating schedule of Mir now that it is a commercial vehicle is somewhat uncertain. Please also note that from time to time both stations use their own or attached vehicles engines to restore orbital height lost to atmospheric drag . So if you want accurate predictions for visual or radio tracking you must make sure that the Keplerian orbital elements in your tracking software are bang up to date.