| Date: | 1996-12-09 10:00:00 | |
| Sender: | T.A. Springer <[Mailed EDC <slrmail@dgfi.badw-muenchen.de>]> | |
| Subject: | [SLR-Mail] No. 34: SLR-GPS Quicklook Service | |
| Author: | T.A. Springer | |
| Content: | ******************************************************************************** SLR Electronic Mail 1996-12-09 10:00:00 UTC Message No. 34 ******************************************************************************** Author: T.A. Springer Subject: SLR-GPS Quicklook Service Dear Colleagues, Today CODE will start its SLR-GPS quicklook service based on the SLR observations taken from the two GPS satellites PRN 5 and PRN 6. The Center of Orbit Determination in Europe (CODE) is one of at present seven Analysis Centers within the IGS (International GPS Service). CODE is a joint venture of the following institutes: - the Swiss Federal Office of Topography (L+T), - the French ”Institute Geographique National” (IGN), - the German Institute for Applied Geodesy (IfAG), and - the Astronomical Institute of the University of Berne (AIUB). The CODE Analysis Center is located at the AIUB. At CODE, like at several other IGS analysis centers, we have started to look into the SLR observations of the GPS satellites since they provide an independent check of our orbit quality. This ”orbit check” has confirmed that the quality of the CODE orbits is at the 50 to 100 mm level. At the same time this shows that there are no significant differences between SLR and GPS. Therefore we are planing to including the SLR data into our routine IGS analysis. This will be of mutual benefit to both observation techniques since it will unify the reference frames of both techniques and show possible discrepancies between SLR and GPS. As a first step towards the combination of both observation techniques we have started to routinely monitor the SLR observations using our rapid orbits and our final orbits. Since our daily rapid orbits are available around 14:00 UTC, only 14 hours after the end of the observation day (!), they provide the possibility to give a very rapid feedback on the quality of the SLR observations. Therefore we have offered to the SLR community to set up this SLR-GPS quicklook service. We hope you will appreciate this service and that you keep tracking the GPS satellites. The SLR-GPS quicklook results will be distributed by e-mail every day provided that there was data for the last day. We have tried to make the reports look similar to the CSR quicklook reports since we assume everyone is used to those. Below I have included yesterday´s report as an example of how our reports will look like. Furthermore I have included the current e-mail distribution list. If you have any questions/remarks about our reports or if you want to be removed/added to the distribution list please send me an e-mail. Kind regards, Tim Springer CODE Analysis Center ------------------------------------------------------------------------------ Tim Springer Astronomical Institute, University of Berne Tel: +41 31 6318592 Sidlerstrasse 5, CH-3012 Bern, Switzerland Fax: +41 31 6313869 ftp: ubeclu.unibe.ch -or- 130.92.6.11 e-mail: springer@aiub.unibe.ch after login: cd aiub$ftp www: http://ubeclu.unibe.ch/aiub/ ------------------------------------------------------------------------------ Current SLR-GPS quicklook e-mail distribution list -------------------------------------------------- pjs@astro.as.utexas.edu ! Peter J. Shelus (McDonald Obs. Texas) kirchner@flubiw01.tu-graz.ac.at ! Georg Kirchner (Graz, Austria) ogara@lure.ifa.hawaii.edu ! Dan O´Gara (LURE, Hawaii) deckerw@thorin.atsc.allied.com ! Win M. Decker (ATSC, NASA Network) glotov@geozup.rsa.ru ! V.D. Glotov (Russiun Network) epavlis@helmert.gsfc.nasa.gov ! Erricos C. Pavlis (GSFC, USA) ats@ast.cam.ac.uk ! Andrew Sinclair (European Network) schreiber@wettzell.ifag.de ! Uli Schreiber (Wettzel, Germany) johnluck@auslig.gov.au ! John Luck (Orroral, Australia) lapushka@astr2.lu.lv ! Kasimir Lapushka (Riga) gurtner@aiub.unibe.ch ! Werner Gurtner (CODE/AIUB) springer@aiub.unibe.ch ! Tim Springer (CODE/AIUB) Example of SLR-GPS quicklook report (for December 4, 1996) ---------------------------------------------------------- Center for Orbit Determination in Europe/ Astronomical Institute, University of Berne (CODE/AIUB) GPS PRN 5 & PRN 6 Quicklook Residual Analysis Report Contact : T.A. Springer (springer@aiub.unibe.ch) Processing Strategy: -------------------- - Each day the SLR observations gathered over the last 6 days are evaluated using the CODE IGS Orbits. The last 4 days are analysed using the CODE ”Rapid” orbits. The 2 older days are analysed using the CODE ”Final” Orbits. The final orbits have an estimated precision of about 50 mm whereas the rapid orbit precision varies between 50 and 150 mm. - We use the SLR observations together with our orbits and the ITRF94 coordinates of the SLR sites to compute the difference between the observed SLR ranges and the computed ranges (OMC). - A summary of the resulting OMC residuals per station and satellite pass is generated. We have tried to make it look like the CSR Lageos-1 & Lageos-2 Quicklook Reports. - The summary contains: STATION ID: Station CDP number and first 4 characters of the station name SAT PRN : The GPS Pseudo Random Noise (PRN) number (5 or 6 for SLR) START PASS: Start time of the SLR observation pass DUR : Duration of the SLR observation pass #OBS GOOD : Number of accepted SLR observations. MEAN : Mean of the OMC residuals (in millimeters) RMS : RMS of the OMC residuals around the MEAN. (in millimeters) #OBS BAD : Number of rejected SLR observations. MEAN : Mean of the BAD OMC residuals (in meters) RMS : RMS of the BAD OMC residuals around the MEAN. (in meters) - Currently only observations of which the OMC residual is larger than 1 meter are rejected. - The ”MEAN” will absorb possible range biases, to a large extend also possible time biases and a part of the GPS Orbit error the. The ”RMS” (around the mean) gives a reasonable representation of the noise of the SLR observations. In cases where an satellite eclips event was tracked the rms will be larger than the noise of the observations. Furthermore for long passes the satellite orbit error will start to show up in the rms. STATION ID SAT START PASSAGE DUR #OBS MEAN RMS #OBS MEAN RMS PRN yy/mm/dd hh:mm (min) GOOD (mm) (mm) BAD (m) (m) ------------------------------------------------------------------------------ 7839 GRAZ 5 96/11/29 17:13 116 7 -22 16 7110 MONP 5 96/12/01 07:09 28 7 -209 4 7110 MONP 5 96/12/02 06:53 211 9 -144 5 1 372 0 7110 MONP 5 96/12/04 06:27 54 8 -110 18 7110 MONP 6 96/12/01 09:54 222 7 -50 108 1 346 0 7110 MONP 6 96/12/02 13:35 3 0 0 0 3 231 212 7080 FDAV 5 96/12/01 07:22 9 3 -248 7 7080 FDAV 5 96/12/02 07:00 8 3 -174 18 7080 FDAV 6 96/12/01 11:02 18 5 -190 9 7080 FDAV 6 96/12/02 11:22 9 4 -57 10 7210 MAUI 5 96/12/02 05:45 23 3 -33 4 7210 MAUI 5 96/12/04 04:28 3 3 47 9 7210 MAUI 6 96/12/03 05:59 355 20 -1 74 7210 MAUI 6 96/12/04 11:12 74 17 -3 26 7918 GREE 6 96/12/02 10:11 111 7 -85 67 10 93 240 ------------------------------------------------------------------------------ [Mailed From: EDC ******************************************************************************** |