[IGS-Equipment-Files] igs08_1785.atx: Update including TRM55970.00

[Ralf Schmid]

Dear IGS colleagues!

The absolute IGS antenna correction file (igs08_wwww.atx) has been 
updated. The new release is called 'igs08_1785.atx'. It contains the 
following changes:

1) The robot-based calibration values for the "TRM57970.00     NONE" 
antenna were copied to the following antenna type:

TRM55970.00     NONE

The only difference between the two antenna types is the soldering material:
> | TRM55970.00          |  Zephyr GNSS II - lead-based solder                   |
...
> | TRM57970.00          |  Zephyr GNSS II - RoHS compliant solder               |
ftp://igs.org/igscb/station/general/rcvr_ant.tab

The similarity of the phase center behavior for these two antenna types 
was not verified by calibration. However, the difference between two 
comparable types (TRM55971.00 vs. TRM57971.00) is more or less below the 
accuracy level of the robot-based calibration approach.

TRM55970.00 antennas were recently installed at several SIRGAS stations 
(CUEC, MHEC, PREC).


2) A decommission date for the following satellite was added:

G06 (G036): 3 March 2014

According to NANU 2014019 
(http://celestrak.com/GPS/NANU/2014/nanu.2014019.txt), Block IIA 
satellite PRN06/SVN36 was already removed from the GPS constellation on 
21 February 2014. However, according to the IGS tracking statistics 
provided by CODE, it didn't stop signal transmission before 3 March 2014 
(DOY 62):
ftp://ftp.unibe.ch/aiub/igsdata/odata_gnss_day.txt


The updated antenna correction model is available at
ftp://igs.org/pub/station/general/igs08_1785.atx
or
ftp://igs.org/pub/station/general/igs08.atx

With best regards,
Ralf Schmid
on behalf of the IGS Antenna Working Group