[IGSMAIL-6711] igs08_1722.atx: Update including reactivated GLONASS satellites

[Robert Khachikyan]

Dear IGS colleagues!

The absolute IGS antenna correction file (igs08_wwww.atx) has been 
updated. The new release is called 'igs08_1722.atx'. It contains the 
following changes associated with almanac slot 8:

1) According to NAGU 093-121225, GLONASS-M satellite R712 was replaced 
by GLONASS-M satellite R743 at the end of December:
> NOTICE ADVISORY TO GLONASS USERS (NAGU) 093-121225
> SUBJ: 08/-6 (743) PUT INTO OPERATION 25.12/1052 MT
> 1.CONDITION: 08/-6 (743) PUT INTO OPERATION 25.12/1052 MT (UTC+0300)
http://www.glonass-ianc.rsa.ru/en/CUSGLONASS/index.php

Richard Langley reported that the switch actually took place on 21 
December:
> On 21 December, GLONASS 712 was deactivated and replaced in almanac
> slot 8 by GLONASS 743, most lately a spare or reserve satellite.
https://listserv.unb.ca/cgi-bin/wa?A2=CANSPACE;7541ae53.1212

Therefore, the following satellite has been added to igs08.atx:

R08 (R743)

2) According to the Information-Analytical Centre, R743 was then 
replaced by GLONASS-K1 satellite R801 on 5/6 January 2013:
> According to GLONASS System Control Centre SC Glonass-M #743 (orbital 
> slot 2) will be set unusable from 10:00 05.01.13 (MT) till 12:35 
> 15.02.13 (MT) for the works on moving SC to orbital slot 8
http://www.glonass-ianc.rsa.ru/en/content/news/?ELEMENT_ID=378
> According to GLONASS System Control Centre from 01:00 06.01.13 (MT) 
> till 12:35 15.02.13 (MT) experimental work will be conducted with SC 
> Glonass-K #701 (in flight tests phase). In the almanac Glonass-K #701 
> will be designated under system number 8
http://www.glonass-ianc.rsa.ru/en/content/news/?ELEMENT_ID=380

Further information was provided by Richard Langley:
https://listserv.unb.ca/cgi-bin/wa?A2=CANSPACE;13add99e.1301

Therefore, the following satellite has been added to igs08.atx:

R08 (R801)

3) Decommission dates for the following satellites have been added:

R08 (R712): 21 December 2012
R08 (R743): 5 January 2013
R26 (R801): 5 January 2013


The updated antenna correction model is available at
ftp://igs.org/pub/station/general/igs08_1722.atx
or
ftp://igs.org/pub/station/general/igs08.atx

With best wishes for the new year,
Ralf Schmid and Robert Khachikyan
on behalf of the IGS Antenna Working Group