Subject: [IGSREPORT-36] JPL analysis report
From: David C Jefferson
Date: 7 DEC 1992 11:23:24

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IGS Electronic Report      7-DEC-1992 11:23:24       Message Number 36
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From:    David C Jefferson
Subject: JPL analysis report
         -------------------

Submitted by

J F Zumberge, G Blewitt, M B Heflin, D C Jefferson, F H Webb

all at the Jet Propulsion Laboratory, California Institute of Technology, 
Pasadena, CA  91109.

The following files have been posted on BODHI (for access to BODHI contact
[email-masked]):

______________________________________________________________________________
filename               contents
______________________________________________________________________________
jpl06717.sum           This text file.
jpl06717.erp           Earth rotation parameters for GPS week 671.
jpl06717.sp1           GPS ephemerides for GPS week 671, sp1 format.
jpl06717.sp3            "       "       "   "   "    " , sp3   "   .
______________________________________________________________________________

Modifications have been made to the JPL analysis strategy in the values
for the nominal station dry tropospheric delays, station antenna
heights, nominal station coordinates, and gravity field.  The analysis
of 92 November 18 and subsequent days reflect these changes.

The changes in station coordinates and antenna heights were made so that
they are consistent with the September 1992 release of ITRF91 (see IGS
Mail 90) at epoch 1992 November 1.  (The previous JPL analyses used
epoch 1992 August 1.)

Two days (Nov 10 and Nov 17) have been processed with both the old and
new strategies.  Based on these, we find that the strategy change
affects the ephemerides at the 4- to 13-cm level for the 3-D RSS over
24-hours.  The following table summarizes the differences in polar
motion and LODR:

                      Xpole (")          Ypole (")             LODR (s/day)

Nov 10 old strategy    .14450             .46698                  .00245
       new             .14488             .46693                  .00245

       new-old         .00038            -.00005                  .00000

Nov 17 old             .15973             .45673                  .00253
       new             .16002             .45665                  .00251

       new-old         .00029            -.00008                 -.00002

Again, our submitted results reflect the new strategy beginning with the
Nov 18 analysis.  The remainder of our narrative summarizes the strategy
changes.

NOMINAL DRY TROPOSPHERIC DELAY.

In the new strategy, the assumed dry tropospheric delay is based on the
station elevation instead of a fixed 2.0000 m.  The nominal dry delays
now range from 1.9199 m (HART) to 2.3056 (RCM2), and are based on

             D(H) = D(0) * exp {-H/h}

where D is the dry delay, H is the station elevation, D(0) =~ 2.300 m ,
and h =~ 8621 m.

ANTENNA HEIGHTS

For maintaining compatibility with previous work using GIPSY at JPL, we
use antenna offsets as measured from the monument to the bottom of the
antenna.  For the Rogue choke-ring/antenna assembly, the physical bottom
of the antenna is the top of the choke ring.  We realize that this is
different from the location of the ARP (antenna reference point) to
which antenna heights are referred by the IGS.  This difference is equal
to the thickness of the choke ring (7.0 cm).  Our antenna heights are
thus equal to the IGS values plus 7.0 cm in the local vertical.

The following antenna heights (including choke ring thickness, per the
above discussion) have been changed in the JPL analyses (* indicates a
fiducial station):

STATION     PREVIOUS VALUE (m)     CURRENT VALUE (m)
 ALBH              0.129                 0.188
 HERS              0.000                 0.270
 MASP              0.000                 0.192
 ONSA              1.066                 1.065
*SANT              0.163                 0.164
 STJO              0.000                 0.232
 TAIW              0.000                 1.836
 WETT              1.668                 0.000

STATION COORDINATES

Some of the nominal station coordinates at epoch 1992.5 in the previous
JPL FLINN analysis were found to be inconsistent with ITRF91.  The
nominal locations for the following stations have been changed by the
following amounts:

STATION              X (m)                Y (m)                Z (m)
*HART                0.054                0.000                0.000
 MCMU                0.003               -0.007                0.036
 PAMA               -7.024               -4.346               -2.463
*SANT                0.047               -0.023                0.000
 STJO                0.022               -0.003                0.017
 USUD                0.099               -0.235               -0.167

STATION VELOCITIES

Velocities for the following stations, formerly assumed zero, have been updated.

STATION           dX/dt (m/y)          dY/dt (m/y)          dZ/dt (m/y)
 ALBH               -0.018               -0.001              -0.010
 MCMU                0.010               -0.010               0.003
 STJO               -0.018               -0.002               0.009

The velocity of SANT (a fiducial station), formerly assumed (incorrectly) to be
(-0.005,-0.008,+0.003) [(dX/dt,dY/dt,dZ/dt), m/y)], is now assumed to be
(-0.001,-0.005,+0.008).

GRAVITY FIELD

We begin using the new Joint Gravity Model 1 (JGM-1) gravity field
(truncated to 8x8) from NASA/Goddard Space Flight Center and the Center
for Space Research at the University of Texas at Austin, according to
whom "JGM-1 is a complete reiteration of the GEM-T3 model using improved
models and constants."  Steve Nerem on Internet at [email-masked],
Phone (301) 286-3220, may be queried for futher information.

GENERAL

A-S testing occurred during "21 Nov 0100 UT to 23 Nov 0100 UT" according
to the file pub/gps/gpstd.txt obtained from tycho.usno.navy.mil. Results for
Saturday, Nov 21 are not included in this submission.

WARNING: No warnings for GPS week 671.

JPL LODR TABLE                               GPS week 671 (1992 Nov 15 - Nov 20)
  MJD       LODR     +/-
          (ms/day)
 48941.5    2.22     0.06
 48942.5    2.49     0.06
 48943.5    2.53     0.06
 48944.5    2.53     0.06
 48945.5    2.57     0.06
 48946.5    2.66     0.05
END LODR TABLE

NOTE: In the following table, UT1R-UTC are the assumed nominal values from
IERS Bulletin-B predicts; estimated LODR values are given in the previous
table. See IGS Mail Message 97 for details.

JPL UTPM TABLE                               GPS week 671 (1992 Nov 15 - Nov 20)
  MJD       X        Y       UT1R-UTC XSIG    YSIG   UTSIG  RMS  XYC  XUC  YUC STA SAT PASS    
           ''        ''        sec     ''     ''      sec
 48941.5   .15471   .45916   .17841  .00015  .00016  .00000  .0 -.07  .00  .00  28 19  0
 48942.5   .15758   .45807   .17607  .00015  .00016  .00000  .0 -.05  .00  .00  28 19  0
 48943.5   .15973   .45673   .17374  .00015  .00017  .00000  .0 -.02  .00  .00  27 19  0
 48944.5   .16176   .45558   .17142  .00016  .00017  .00000  .0 -.02  .00  .00  27 19  0
 48945.5   .16353   .45418   .16909  .00016  .00018  .00000  .0 -.05  .00  .00  27 19  0
 48946.5   .16655   .45287   .16677  .00015  .00016  .00000  .0 -.09  .00  .00  27 19  0
END UTPM TABLE

The following table indicates the "3-dimensional orbit repeatability", as 
defined in IGS Mail Message 37, for GPS week 671:
["3d rss" = sqrt(xrms**2 + yrms**2 + zrms**2)]

JPL ORBIT REPEATABILITY TABLE                GPS week 671 (1992 Nov 15 - Nov 20)
      92 11 15   92 11 16   92 11 17   92 11 18   92 11 19   92 11 20
prn   3d rss (m)
  2       1.19       1.36       0.92       0.38       0.37       0.2 
  3       0.42       0.26       0.27       0.41       0.47       0.5 
 11       0.51       0.43       0.22       0.14       0.28       0.5 
 12       0.55       0.34       0.26       0.23       0.26       0.4 
 13       0.48       0.40       0.56       0.28       0.16       0.2 
 14       0.74       0.38       0.60       0.20       0.30       0.5 
 15       0.61       0.38       0.78       0.67       0.40       0.8 
 16       0.42       0.36       0.61       0.52       0.61       0.6 
 17       1.05       0.28       0.12       0.42       0.33       0.1 
 18       0.42       0.48       0.37       0.36       0.32       0.2 
 19       0.58       0.56       0.47       0.35       0.35       0.2 
 20       0.27       0.33       0.17       0.20       0.21       0.3 
 21       0.67       0.49       0.28       0.30       0.41       0.4 
 23       0.28       0.48       0.39       0.64       0.15       0.1 
 24       0.35       0.47       0.25       0.17       0.33       0.6 
 25       0.27       0.41       0.16       0.18       0.27       0.2 
 26       0.34       0.20       0.49       0.41       0.35       0.2 
 27       0.56       0.22       0.44       0.16       0.43       0.4 
 28       1.35       1.51       0.27       0.62       0.34       0.3 
END ORBIT REPEATABILITY TABLE

As described in IGS Mail Message 37, the following table compares the JPL
precise ephemerides with those from the broadcast ephemeris:

JPL COMPARISON OF BROADCAST NAVIGATION MESSAGE WITH PRECISE EPHEMERIDES
      92 11 15   92 11 16   92 11 17   92 11 18   92 11 19   92 11 20
prn   3d rss (m)
  2       6.2        4.2        3.5        2.7        2.5        3.5 
  3      18.2       17.4       17.6       15.6       14.3       14.3 
 11       2.7        2.4        2.0        3.2        1.2        7.4 
 12      10.0        4.3        4.5       12.5       22.3       28.6 
 13       5.4        5.3        5.6        7.1        7.1        2.4 
 14       5.6        5.2        6.9        8.0        8.4        8.0 
 15       2.6        2.0        2.1        4.2        5.1        3.6 
 16      10.6        7.1        6.0        6.0        5.2        6.2 
 17       3.3        3.4        3.1        3.8        3.8        4.1 
 18       7.9        7.2        8.3        6.5        7.9        7.0 
 19       8.4        5.2        5.2        5.8        5.6        6.9 
 20       3.7        3.5        4.2        3.8        5.1        6.4 
 21       3.8        3.9        4.5        5.4        3.4        8.3 
 23      10.3       11.7        9.1       11.9       13.3       13.6 
 24       7.3        7.2        5.8        5.7        5.9        5.7 
 25      12.1        8.1        9.6        9.2       13.5       10.6 
 26      10.6       10.6        7.6        7.9        9.0       12.2 
 27      11.4       12.4       12.6       11.8       11.2       13.2 
 28       6.6        8.4       11.7       13.5       15.9       18.7 
END COMPARISON OF BROADCAST NAVIGATION MESSAGE WITH PRECISE EPHEMERIDES

The following table, as explained in IGS Mail Message 91, indicates which
tracking sites were used in this week's analysis:

JPL GROUND STATION INCLUSION TABLE           GPS week 671 (1992 Nov 15 - Nov 20)
      92 11 15   92 11 16   92 11 17   92 11 18   92 11 19   92 11 20

ALBH      X          X          X          X          X          X           
ALGO*     X          X          X          X          X          X           
DRAO      X          X          X          X          X          X           
FAIR*     X          X          X          X          X          X           
GOLD      X          X          X          X          X          X           
HART*     X          X          X          X          X          X           
JPLM      X          X          X          X          X          X           
KOKB*     X          X          X          X          X          X           
KOSG      X          X          X          X          X          X           
MADR*     X          X          X          X          X          X           
MASP      X          X          X          X          X          X           
MATE      X          X          X          X          X          X           
MCMU      X          X          X          X          X          X           
METS      X          X          X          X          X          X           
NYAL      X          X                                                       
ONSA      X          X          X          X          X          X           
PAMA      X          X          X          X          X          X           
RCM2      X          X          X          X          X          X           
SANT*     X          X          X          X          X          X           
STJO      X          X          X          X          X          X           
TAIW      X          X          X          X          X          X           
TIDB      X          X          X          X          X          X           
TROM*     X          X          X          X          X          X           
USUD      X          X          X          X          X          X           
WETT      X          X          X          X          X          X           
YAR1*     X          X          X          X          X          X           
YELL      X          X          X          X          X          X           
_______________________
*Indicates fiducial site.
END GROUND STATION INCLUSION TABLE