[IGSMAIL-226] SIO developments

[Y.]

IGS Electronic Mail       18-MAR-1993 09:10:26       Message Number 226
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From:	Y. Bock
Subj:   SIO developments
------------------------


  
Scripps Orbit and Permanent Array Center announces several developments to

(1) The IGS community
(2) UNAVCO investigators
(3) GAMIT users

Submitted by: Yehuda Bock, Peng Fang & Keith Stark
              Institute of Geophysics and Planetary Physics (IGPP)
              Scripps Institution of Oceanography (SIO)
              La Jolla, CA 92093-0225 USA
              Date: March 17, 1993
              e-mail: bock[pfang,stark]@pgga.ucsd.edu
              fax: (619) 534-5332
              geodesy lab tel: (619) 534-7692

Feedback from users is strongly encouraged and greatly appreciated.

_________________________________________________________________________________
(1) SIO products: Orbits (.eph) Polar motion (.erp) and Summary files (.sum)
have been recomputed for the 15 month period:
 GPS weeks 0606 - 0670 (August 18, 1991 to November 18, 1992).

These products use ITRF91 station coordinates computed at SIO and described in
IGS mail # 168, and are consistent with products computed from weeks 0676 to
the present time. Note that we have still have a five week gap between weeks
0671-0675 which will be archived upon completion.

To access SIO GARNER archive:
 ftp teddy at ucsd.edu (132.239.13.4)
 login: anonymous
 password: your name
 directories: igs_products (subdirectories according to GPS week)
Direct problems to: stark at pgga.ucsd.edu

Updated SIO products will also be put on CDDIS archive (at least
from the start of the IGS campaign).

Caution: Please scan the .sum files before using a particular orbital day.
Look for any satellites that have large overlap errors, or for remarks that
indicate that a particular satellite has a problem.

Caution: The products from weeks 0606 to 0610 suffer from a weak tracking
configuration, and therefore should be used with caution. The products
from weeks 0611 to 0616 are marginal for the same reasons. The products
from weeks 0617 onward are of good quality and progressively improve
as new tracking stations are added to the daily analysis.

Note for UNAVCO investigators: We will no longer maintain the directory
garner_orbits with the ngarn[yy].[day] file structure. This is replaced by the
IGS naming conventions for orbits. For example for GPS week 0685:
_________________________________________________________________________________
filename               contents
_________________________________________________________________________________
sio06857.sum        A weekly summary file.
sio06857.erp        Polar motion parameters for GPS week 0685.
sio0685[0-6].eph    Daily ephemerides for GPS week 0685, SP1 format.
                     [0=Sunday => 6=Saturday]
                    (these files are equivalent to ngarn93.052 => ngarn93.058)
_________________________________________________________________________________

UNIX scripts for converting between [GPS week, day of week] & [year, day of year]
                        and between [Calendar date] & [year, day of year]
can be found in igs_products/utilities [named gweek & jday, respectively]

Note for GAMIT users: GAMIT g-files used to generate the daily SIO orbits can be
found under gamit_orbits/[yy]data

_________________________________________________________________________________
(2) Station and antenna information can be found under:
  igs_products/sites_antennas

The following files are included:

 a) station.info : history of site occupations at IGS and PGGA sites,
    including receiver codes, antenna codes & heights (see hisub.ftn),
    firmware versions, comments, etc.

 b) IGS mail #168 describing SIO coordinates

 c) pgga_921205.itrf91 : SIO ITRF91 station coordinates (reference frame)

 d) hisub.ftn : Fortran subroutine that contains up-to-date list of antenna
    information, including antenna height conversions, phase center offsets, etc.

 e) additional files as needed and requested
_________________________________________________________________________________
(3) Effective GPS week 0688, Clean RINEX files will now be archived under:
 igs_products/pgga_solutions/[yy]data/[ddd]

These files have had data outliers removed and are cycle-slip free.
That is, any combination of doubly-differenced data within this group
of stations will be cycle-slip free. However, the undifferenced phase
data may have undetected slips.

The antenna height in the files are given according to the RINEX standard,
direct height pre-amp base.

The sampling interval of the clean RINEX files is 120 seconds.

To obtain clean RINEX data before GPS Week 0688 contact: stark at pgga.ucsd.edu

Note for GAMIT users: Clean GAMIT X-files can be found in the same directories
as the clean RINEX files.