| Date: | 2003-08-22 08:53:00 | |
| Sender: | Van S. Husson, ILRS Central Bureau <Husson, Van <Van.Husson@honeywell-tsi.com>> | |
| Subject: | [SLR-Mail] No. 1118: 7357 Beijing Updated Coordinates | |
| Author: | Van S. Husson, ILRS Central Bureau | |
| Content: | ******************************************************************************** SLR Electronic Mail 2003-08-22 08:53:00 UTC Message No. 1118 ******************************************************************************** Author: Van S. Husson, ILRS Central Bureau Subject: 7357 Beijing Updated Coordinates Dear Colleagues, Ron Noomen was kind enough to provide some updated coordinates/velocities for the new Beijing system (7357) in the ITRF2000 reference system (i.e. Epoch 1997). The two coordinate sets below were each based on one week of LAGEOS data. DATE X SIGMA Y SIGMA Z SIGMA YYMMDD (M) (M) (M) (M) (M) (M) ------- ------------ ------ ----------- ------ ----------- ----- 30806 -2148781.444 0.006 4426678.197 0.007 4044571.632 0.007 30813 -2148781.413 0.005 4426678.164 0.005 4044571.665 0.006 ------------ ----------- ----------- avg -2148781.428 4426678.181 4044571.649 The NUVEL-1A velocities are: xdot(m/yr) ydot(m/yr) zdot(m/yr) ---------- ---------- ---------- -0.02427 -0.00286 -0.00977 The average position and velocities above should be an excellent a priori position and good to better than 10cm. The ITRF2000 velocities for Beijing are suspect and are NOT recommended. Here are the Velocities for the Chinese systems near Beijing in XDOT, YDOT, ZDOT and NEU (all units are in meters/year). Source Site City XDOT YDOT ZDOT North East UP -------- ---- ------- ------- ------- ------- ------- ------ ------- ITRF2000 7249 Beijing -0.0444 0.0141 -0.0013 -0.0214 0.0338 0.0239 NUVEL1A 7249 Beijing -0.0243 -0.0029 -0.0098 -0.0127 0.0231 -0.0001 ITRF2000 7236 Wuhan -0.0325 -0.0077 -0.0119 -0.0135 0.0328 -0.0005 ITRF2000 7837 Shanghai-0.0307 -0.0112 -0.0134 -0.0147 0.0321 -0.0015 ITRF2000 7237 Changchu-0.0218 -0.0083 -0.0092 -0.0107 0.0226 -0.0021 The NUVEL 1A rates for Beijing appear to be more realistic in light of the ITRF2000 velocities for its nearest neighbors. Note the large ITRF2000 up component of 24mm/year. Below is a June 2003 local tie provided by the Chinese between 7357, 7249 and BJFS: BJFS-7357 (XYZ in meters) are 37.627 -37.017 84.348 7249-7357 (XYZ in meters) are 21.111 81.299 -61.855 Based on the local tie, Ron´s average coordinates for 7357, here is an updated position for 7249 at epoch 1997: X Y Z ------------ ----------- ----------- -2148760.318 4426759.480 4044509.794 I hope these coordinates provide better fits to the SLR data. From: ”Husson, Van” ******************************************************************************** |