[IGSMAIL-6789] igs08_1748.atx: Update including GLONASS-M satellite R747

[Robert Khachikyan]

Dear IGS colleagues!

The absolute IGS antenna correction file (igs08_wwww.atx) has been 
updated. The new release is called 'igs08_1748.atx'. It contains the 
following changes:

1) A single GLONASS-M satellite launched on 26 April 2013 was added with 
a preliminary z-offset value of 245 cm:

R747 (R02)

2) A decommission date for the following satellite has been added:

R728 (R02): 30 June 2013

Sources:

NAGU 054-130701:
> NOTICE ADVISORY TO GLONASS USERS (NAGU) 054-130701
> SUBJ: 02/-4 (728) UNUSABLE 01.07/0622 MT - UNFINISHED
> 1.CONDITION: 02/-4 (728) UNUSABLE SINCE 01.07/0622
>  MT (UTC+0300) UNTIL FURTHER NOTICE DUE TO MAINTENANCE

NAGU 056-130704:
> NOTICE ADVISORY TO GLONASS USERS (NAGU) 056-130704
> REF: 055-130702
> SUBJ: 02/-4 (747) PUT INTO OPERATION 04.07/1430 MT
> 1.CONDITION: 02/-4 (747) PUT INTO OPERATION 04.07/1430 MT (UTC+0300)
http://glonass-iac.ru/en/CUSGLONASS/index.php

Richard Langley via Canspace:
> GLONASS 747, a reserve satellite launched on 26 April 2013 and 
> fortuitously residing near orbital slot 2, took over the role of R02 
> at about 12:10 UTC on 1 July according to MGEX tracking data.
https://listserv.unb.ca/cgi-bin/wa?A2=CANSPACE;bdd2850a.1307


3) One additional robot calibration provided by NovAtel Inc. and 
performed by Geo++ GmbH:

NOV703GGG.R2    NONE


The updated antenna correction model is available at
ftp://igs.org/pub/station/general/igs08_1748.atx
or
ftp://igs.org/pub/station/general/igs08.atx

Those who still didn't switch to the GPS satellite antenna PCV extension 
can use the following model:
ftp://igs.org/pub/station/general/igs08_1748_woPCVextension.atx
(Parallel files will only be provided until about end of July!)

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