Dear AC colleagues, we would like to announce that we just completed the compilation of a consistent set of mean antenna phase center offsets and elevation-dependent phase center corrections for the antenna types existing in the global IGS network. The set of phase center calibration values has been named IGS_01. All the information concerning this set will soon be available at the IGS Central Bureau Information System. The files may be downloaded already now from the anonymous ftp account in Berne: ftp ubecx.unibe.ch (130.92.6.40) userid: anonymous passwd: "e-mail address" cd aiub cd antennas ... ... A description of the combination procedure and the results is given in the file IGS_01.TXT. There you will also find a list of all the other files available in this context (plots, tables ...). In agreement with the analysis center coordinator, Jan Kouba, we recommend to start testing and using these calibration values as soon as possible. To assess the impact of these phase center corrections on a global IGS network a 1-day solution was computed at CODE, where these new phase center corrections were applied, and compared to a solution with NO elevation- dependent phase center corrections at all (at CODE we already use an old set of correction values for the Trimble antennas in the routine processing): HELMERT TRANSFORMATION BETWEEN A SOLUTION USING THE NEW PHASE CENTER CALIBRATIONS AND A SOLUTION WITHOUT ANY ELEVATION-DEPENDENT CORRECTIONS ----------------------------------------------------------------------- TRANSFORMATION IN EQUATORIAL SYSTEM (X, Y, Z): RESIDUALS IN LOCAL SYSTEM (NORTH, EAST, UP) F: FIXED SITES M: MARKED SITES (NOT USED TO COMPUTE THE TRANSFORMATION PARAMETERS AND THE RMS VLAUES) -------------------------------------------------------------- | NUM | NAME | RESIDUALS IN MILLIMETERS | | | | | NORTH EAST UP | | -------------------------------------------------------------- | | | | | | 111 | NYAL 10317M001 | 0.4 0.0 2.7 | | | 117 | JOZE 12204M001 | -5.7 6.0 -121.0 | M | | 121 | BRUS 13101M004 | -0.5 -0.4 4.0 | | | 122 | MASP 31303M001C | -1.2 -1.1 -9.3 | | | 123 | BOR1 12205M002 | -0.2 0.4 7.8 | | | 151 | GRAZ 11001M002 | -0.5 0.3 3.8 | | | 152 | HERS 13212M007 | -0.5 -0.8 4.5 | | | 153 | KOSG 13504M003 | -0.1 -0.3 -2.5 | F | | 154 | MADR 13407S012 | -0.5 -0.4 -2.4 | F | | 155 | MATE 12734M008 | -1.0 0.6 4.9 | | | 156 | TROM 10302M003 | 0.3 -0.2 -2.5 | F | | 157 | WETT 14201M009 | -0.2 -0.2 -2.5 | F | | 158 | ZIMM 14001M004 | -5.6 5.9 -111.9 | M | | 159 | ONSA 10402M004 | 0.2 -0.1 6.4 | | | 160 | METS 10503S011 | 0.3 0.6 7.3 | | | 161 | WTZR 14201M010 | -0.5 0.1 5.1 | | | 171 | POTS 14106M003 | -0.2 0.1 6.2 | | | 172 | LAMA 12209M001 | -0.3 0.5 7.7 | | | 173 | MDVO 12309M001 | -6.4 6.8 -112.1 | M | | 174 | THUL | -0.2 -0.6 -3.3 | | | 179 | GOPE 11502M002 | -7.0 5.5 -122.7 | M | | 187 | REYK 10202M001 | 0.2 0.0 -1.1 | | | 194 | UPAD 12750M002 | -5.4 5.5 -123.4 | M | | 202 | TAIW 23601M001 | 0.0 -1.2 1.7 | | | 205 | KIT3 12334M001 | -0.7 2.1 -6.8 | | | 206 | SHAO 21605M002 | 0.0 -0.9 2.3 | | | 208 | IRKT 12313M001 | -0.6 0.1 -1.7 | | | 209 | POL2 12348M001 | -0.8 1.8 -4.4 | | | 251 | USUD 21729S007 | 0.0 0.3 5.5 | | | 254 | TSKB 21730S005 | 0.0 0.5 6.0 | | | 255 | TAEJ 23902M001 | -3.8 4.7 -97.2 | M | | 351 | HART 30302M002 | -1.8 -0.4 -2.0 | F | | 353 | MALI 33201M001 | -0.7 0.4 3.7 | | | 409 | STJO 40101M001B | -0.9 -0.4 -1.6 | | | 412 | KOUR 97301M210 | -1.0 -1.0 -1.3 | | | 413 | QUIN 40433M004 | -0.8 0.0 -1.0 | | | 418 | FORT 41602M001 | -1.0 -1.7 -0.3 | | | 421 | RCM5 40499S018B | -1.0 -0.4 -0.1 | | | 422 | GODE 40451M123 | -0.9 -0.4 -1.2 | | | 450 | ALBH 40129M003 | -0.7 0.1 -1.1 | | | 451 | ALGO 40104M002 | -0.8 -0.4 -1.3 | F | | 452 | FAIR 40408M001B | -0.8 -0.3 -1.3 | | | 453 | GOLD 40405S031 | -0.8 0.0 -1.2 | | | 454 | KOKB 40424M004 | -0.8 1.1 -0.6 | F | | 455 | DRAO 40105M002 | -0.7 -0.1 -1.2 | | | 458 | YELL 40127M003B | -1.0 0.0 -1.5 | F | | 464 | PIE1 40456M001 | -0.7 -0.1 -1.2 | | | 465 | NLIB 40465M001 | -0.9 -0.2 -1.3 | | | 467 | WES2 40440S020 | -0.9 -0.5 -1.6 | | | 469 | BRMU 42501S004 | -1.1 -0.5 -0.8 | | | 472 | MDO1 40442M012 | -0.7 -0.1 -1.4 | | | 473 | AREQ 42202M005B | -0.2 -0.3 -0.4 | | | 474 | EISL 41703M003 | -0.4 0.1 -2.0 | | | 475 | BOGT 41901M001 | -0.8 -0.4 -1.8 | | | 477 | LPGS | 0.3 -1.0 -0.7 | | | 479 | CRO1 43201M001 | -1.1 -0.7 -0.4 | | | 480 | ASC1 | -0.9 -2.3 -1.9 | | | 503 | MCM4 66001M003 | -0.8 1.8 -1.0 | | | 551 | TIDB 50103M108 | -0.8 2.1 -0.7 | F | | 552 | YAR1 50107M004 | -1.6 1.8 -1.5 | F | | 562 | GUAM 50501M002 | -0.2 -0.6 -1.9 | | | 563 | OHIG 66008M001 | 1.0 -0.8 -1.8 | | | 565 | PERT 50133M001 | -1.6 1.7 -1.2 | | | 566 | CHAT 50207M001 | -0.6 1.6 -0.5 | | | 567 | AUCK 50209M001 | -0.8 1.4 -0.5 | | | 568 | KWJ1 | -0.6 0.8 0.2 | | | 901 | PAMA 92201M003 | -0.5 0.6 -1.1 | | | 902 | KERG 91201M002 | -1.4 -0.8 -3.6 | | | | | | | -------------------------------------------------------------- | | RMS / COMPONENT | 0.8 0.9 3.4 | | -------------------------------------------------------------- NUMBER OF PARAMETERS : 7 NUMBER OF COORDINATES :186 RMS OF TRANSFORMATION : 2.1 MM PARAMETERS: TRANSLATION IN X : 0.7 +- 0.3 MM TRANSLATION IN Y : 1.1 +- 0.3 MM TRANSLATION IN Z : 0.9 +- 0.3 MM ROTATION AROUND X-AXIS: - 0 0 0.0000 +- 0.0000 " ROTATION AROUND Y-AXIS: 0 0 0.0000 +- 0.0000 " ROTATION AROUND Z-AXIS: 0 0 0.0000 +- 0.0000 " SCALE FACTOR : 0.0002 +- 0.0000 MM/KM ----------------------------------- The main differences may be seen for the sites equipped with Trimble antennas. The huge change in height is produced by the use of elevation-dependent phase center corrections, whereas the differences in the horizontal components are a direct result of the horizontal offsets that were applied with the new set. It is interesting to see that all the other sites are also changed by introducing the new calibration set, especially in height (up to 9 mm !). A significant scale factor could not be detected and no difference could be found in the 1-day orbits (the largest rotation is below 0.01 mas). It is clear that the introduction of the new antenna phase center corrections will lead to jump in the coordinate time series. The jump in the horizontal components to be expected can easily be computed by forming the ionosphere- free linear combination of the L1 and L2 offsets given in the calibration set. The change in height, however, depends on the elevation cut-off used by the individual analysis centers and cannot easily be predicted. There are still some issues to straighten out in the future. Especially the naming and identification of the Ashtech antenna types is not yet solved and some antenna dimension and drawings are still missing. But this set is to be considered a first important step. Please let us know if you have any problems with the set or the implementation thereof. Some feedback about the first experiences you gain with the set would be very appreciated. With best regards, Markus Rothacher , AIUB Gerry Mader, NGS