While our tracking programs use WGS72 as the datum, the earth is now being measured in the ITRF datum. ITRF stands for International Terrestrial Reference Frame. WGS84 is based off that. While there is lots of datums, anyone with a gps receiver can obtain there site position in WGS84. You can convert older positions in other datums to the WGS84 position. But since tracking programs use WGS72, it doesn't matter what datum you use, since there will be a loss in accurracy. I don't know if norad is using the WGS 84 datum in there calculations but it might be time to start using them. Surveyors use the ITRF datum, to measure the position of survey markers, and gps orbits are in the ITRF datum. If I use a garmin gps25 receiver I can use the gps orbits to measure by position, to around 3 meters or less, or the approx accurracy of the WAAS system. Since alot of gps receivers are going to use WAAS, then it won't be to hard to obtain an accurate position. My question is what datum is used in the calculations of ted molczan, mike mccants and others when they take observations and generate an orbit. Maybe its time we sat observers agree on a datum to use when reporting positions that also is used in orbit computations. Even though right now the orbits are quite good and we can find the object. Just a thought. I was wondering if anyone use a ccd camera not viedo camera for measuring positions. Kevin _________________________________________________________________ Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp ----------------------------------------------------------------- Unsubscribe from SeeSat-L by sending a message with 'unsubscribe' in the SUBJECT to SeeSat-L-request@lists.satellite.eu.org http://www2.satellite.eu.org/seesat/seesatindex.html
This archive was generated by hypermail 2b29 : Thu Aug 16 2001 - 22:28:06 PDT