[IGSREPORT-628] EMR Analysis Report (week 724)

[Jan]

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IGS Electronic Report     30-NOV-1993 22:11:24       Message Number 628
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From: Jan Kouba 
Subj: EMR Analysis Report (week 724) 
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					          (Nov 21 - Nov 27,93)

      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 pilot project  called 
"Active Control System" 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*           
McMurdo                MCMU*            325 to 331  
Pamatai                PAMA             325, 326, 330, 331
Penticton, CAN         DRAO              
Santiago               SANT*          
St. Johns, CAN         STJO            
Canbera                TIDB*           
Tromsoe                TROM*            
Wettzell               WETT*            325 to 327 
Yarragadee             YAR1*            
Yellowknife, CAN       YELL*          
* indicates constrained stations, remaining are solved for (50m apriori sig.)

SOLUTION CHARACTERISTICS

Reference frame and orientation:
      Nominally ITRF91, at epoch 1992.5 is realized by constraining up to 12 
of the above stations at the IGS coordinates (see IGS message #90). 
Orientation is realized through the above coordinates and, once a week, 
the fixed DUT1 values from the current NEOS/IERS (Bull. A).

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 are generated and uploaded into CDDIS @ NASA/GSFC
   EMR07240-6.EPH       GPS ephem. files for days 0-6, week #724 in sp3 format 
   EMR07247.ERP        	pole x,y and DUT1 solutions for week #724
   EMR07247.SUM        	name of this text summary 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 -1110 ns (49312) & -18 ns/day w.r.t.
   GPS time. 
2. Starting with the week #720 we are assigning nominal sigma codes of 8(256mm)
   for all the orbits passing our quality analysis. For errors larger than 1.5m
   we are assigning sigmas of abs(error)/4, expressed by the binary
   exponent in the sp3 header. 
3. PRN4 was introduced in the daily orbit processing as of Nov. 21 (day325). 
4. Only 50% or less data for PRN13 (GPS9) for all days during this week. 
5. A correction was made in our sp3 "generator" to apply a clock sign consistent   with the broadcast clocks.  All emr's sp3 files created since and including
   wk #721 have "correct" clock sign. This change of sign also affected the no
   clock code (99999.) so that weeks 721-723 have the code of -99999. micr. sec.
   The week 724 has been corrected, it has correct sign for both the clock
   solutions and the no clock codes. We apologize for our mistake and any in-
   convenience we might have caused.