| Date: | 2003-03-13 18:30:00 | |
| Sender: | Stefan Riepl (BKG) <stefan.riepl@bkg.bund.de> | |
| Subject: | [SLR-Mail] No. 1063: Re: No.1050 : New laser ranging prediction format | |
| Author: | Stefan Riepl | |
| Content: | ******************************************************************************** SLR Electronic Mail 2003-03-13 18:30:00 UTC Message No. 1063 ******************************************************************************** Author: Stefan Riepl (BKG) Subject: Re: No.1050 : New laser ranging prediction format Dear Randy, I´ve got some comments on the PCLRPF. 1. The correct URL where the format can be found is: http://ilrs.gsfc.nasa.gov/ilrs/working_groups/predictions_format_study_group/ clrpf/index.html ^^^^ 2. Are there any tests carried out by now concerning the normal point generation using these type of predictions ? As I remember from the last working group meeting, the point whether the smoothness of the interpolator output is sufficient for the high precision normal point generation was not quite clear. 3. Is there any special reason why the ephemeris should be in a body fixed system ? Why don´t we use a space fixed system ? 4. The normal point software from RGO, with which we are very happy, requires space fixed coordinates and velocities, which permit a parameter regression of time bias, radial error and their temporal derivatives. We found these parameter estimates very useful for quality check or noise rejection purposes. Are there any plans for the new software package to output a space fixed ephemeris as well ? 5. Regarding the very small time step required for planetary orbiter missions (MGS at Mars = 0.3min) I would propose to leave the coordinate system, in which the ephemeris is given, as a parameter. Doing this, the ephemeris for planetary orbiters could be given in the Mars space fixed coordinate system, which would increase the required step size to the same value as for earth satellites. If we choose e.g. the true of date system for the lunar ephemeris, the step length could be at least increased to 0.3 days. Best regards, Stefan Riepl From: stefan.riepl@bkg.bund.de ******************************************************************************** |