[IGSREPORT-327] EMR Jan93 Orbit Test Report

[Jan]

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IGS Electronic Report     12-JUN-1993 12:04:45       Message Number 327
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From: Jan Kouba 
Subj: EMR Jan93 Orbit Test Report
---------------------------------


    Subject: EMR Reanalysis of the GPS week 680-681
                                                   (Jan. 17 to Jan. 30, 1993)

      Our analysis utilizes the JPL GIPSY/OASIS II (UNIX) software system 
and data from all (up to 7) Canadian stations augmented by up to 12, globally 
distributed, core stations (see Table 1 for the list of stations).  

      This effort is a part of a joint project  called 
"Active Control System" in Canada and involves the Geodetic Survey Division 
(GSD), SMRSS, the Geophysics Division and Pacific Geoscience Centre of the
Geological Survey of Canada, all three institutions are part of the  
Department of Energy, Mines & Resources (EMR).

      Table 1 : Station Summary (also indicated are day no. for which a 
particular station is not included in the daily solution, either due to
being down or data being late). 
                               
   STATION            IGS code       MISSING DAY NO. 1993
Albert Head, CAN       ALBH            
Algonquin, CAN         ALGO*        
Fairbanks              FAIR*                 
Goldstone              GOLD*           
Hartebeesthoek         HART*        
Holberg,CAN            HOLB
Kokee Park             KOKB*            
Madrid                 MADR*           018
McMurdo                MCMU            017 to 023 ; 26 to 30 
Pamatai                PAMA          
Penticton, CAN         DRAO            024, 029, 030
Santiago               SANT*             
St. Johns, CAN         STJO
Canbera                TIDB*                         
Tromsoe                TROM*           
Wettzell               WETT*           
Yarragadee             YAR1*           017 to 020 
Yellowknife, CAN       YELL*               
* indicates fixed stations, remaining are solved for (50m apriori sig.)

SOLUTION CHARACTERISTICS

Reference frame and orientation:
      Nominally ITRF91, at epoch 1993.06 is realized by fixing the 12 
stations at the IGS (SSC(IERS) 93 C 02) coordinates (see IGS message #236)
Orientation is realized through the above coordinates and, by fixing the DUT1
value on Jan 17, 93 obtained from the final values of the IERS Bull.B

Constants and models: 
- no change, see the IGS mess. #101 for details.

Estimation strategies:
- no change, see the IGS mess. #101 for details - , except for the estimation
  of DUT1, stochastic orbit modeling, new weighting of L3,P3,
  see IGS mess. #130.

      ALGO was used as time reference.                           
      Aposteriori variance factors typically are between 0.5 and 1.0 (noise 
about 3mm and 200mm for phase and smoothed pseudorange observations, resp.). 

PRODUCTS GENERATED:
The following products were generated and uploaded into AIUB astronomy/igscomp
   EMR06800-6.EPH        GPS ephem. for week # 680 in sp3 format & in ITRF91
   EMR06810-6.EPH        GPS ephem. for week # 681 in sp3 format & in ITRF91
   EMR06800-6.EPHJ2000   GPS ephem. for week # 680 in sp3 format & in J2000 
   EMR06810-6.EPHJ2000   GPS ephem. for week # 681 in sp3 format & in J2000 
   EMR06817.ERP        pole x,y and DUT1 solutions for weeks # 680, 681
   EMR06817.SUM        name of this text file

REMARKS on EMR's products:
1. ALGO hydrogen maser used as a time reference. In the sp3 EPH file sat.
   epochs with no reference (e.g. ALGO not observing a satellite)
   have a value of 99999. microseconds. 
   ALGO clock error & drift were about -600 ns (49004) and -50 ns/day 
   w.r.t. GPS time.  
2. Modelling problems with PRN11 on Jan17/93. Errors up to 9m! (About 20% and
   50% of the usual amount of data was observed and used for this satellite
   on Jan 17 and 18, respectively)
3.  Due to data problems Penticton was excluded from processing on Jan 24, 29
    30 and MCMU on Jan 26-30, respectively. 
4.  The J2000 ephemeris  is based on the final IERS Bull.B EOP series;
    The ITRF91 ephemeris (*.eph) is based on the EOP sol. in the emr06817.erp
    file above.
5.  DUT1 estimation initialized only once (on Jan 17) and solved for on all
    subsequent days.