Satgen 634 AO40 Orbital Oddity by GM4IHJ (BID SGEN634) 2001-05-19 One thing is for sure. We have never in Amsats 39 years of spacefaring , had an orbit like Oscar Four Zero's . Ao40 has an orbit which is not likely to change all that much , even if the ion drive is used with or without ionisation. So, offering thanks that IHJ did not rebuild the old AO13 high latitude tracker antennas , but decided on a wait and see strategy before sighting new antennas. What can now be done to maximise the useful features of what we now have , post Big Bang ? Seen from 56N latitude , the new equatorial orbit tracks across the station sky from about azimuth 98 degrees through south to azimuth 260 degrees. Never going much above 30 degrees elevation, but with long periods in range at elevations around 20 degrees. So an antenna system located clear and south of the house is required. But while it will need full azimuth rotation over 180 degrees of arc. It need not necessarily need much if any elevation movement . Features which , after 2 weeks of tracking the satellite with the present small portable S band antenna seem to be adequate. Although a more powerful S band antenna to the same design , will be built in slow time, in order to lift apogee signal reception levels on the more difficult to read SSB signals. No problem has been encountered with the existing 24 element 70 cm yagi uplink antenna. Less kind things must be said , about the satellites daily in range time table. In the first half of May 2001, the satellite has never been in range of Scotland on any single day between 1130z and 2000z. At this present time, as seen from GM. AO40 is a midnight cowboy. Loud and clear between midnight and dawn , night after night. Great for insomniacs. But all is not lost . By August 2001 , some days will have in range orbits for Scotland in the late afternoon and evening. While by October 2001, in range orbits will be present on most afternoons. It is appreciated that stations nearer the equator will experience satellite in range windows roughly similar to those reported above for high latitude stations , albeit somewhat modified by their being able to access the satellite for longer periods ,when it is south of the equator . But they will require much greater antenna elevation coverage than the high latitude stations. A brief glance at what southern temperate latitude station can expect , suggests that they like the Scottish stations may have to wait until August for good local evening time operating opportunities , and until October/November 2001 for good afternoon openings. But please note , this latter assesment is purely theoretical . As IHJ has no experience of operating the other way up.