[IGSMAIL-7323] igs08_1903.atx: Update including GLONASS-M satellite R853

[Ralf Schmid]

Dear IGS colleagues!

The absolute IGS antenna correction file (igs08_wwww.atx) has been 
updated. The new release is called 'igs08_1903.atx'. It contains the 
following changes:

1) According to the Information Analytical Centre (IAC), GLONASS-M 
satellite R853 (2016-032A) launched on 29 May 2016 replaced GLONASS-M 
satellite R723 in almanac slot 11 (Please note that R753 is a GLONASS 
satellite launched in 1991!). Therefore, the following satellite has 
been added:

R11 (R853)

The following PRELIMINARY phase center offset (PCO) values were assigned:

PCO_X = -54.5 cm
PCO_Y =   0.0 cm
PCO_Z = 245.0 cm

According to the Center for Orbit Determination in Europe (CODE), R853 
is already active since 24 June 2016 (DOY 176).

NAGU message 035-160627:
> 035-160627
> REF: 033-160624
> SUBJ: 11/00 (753) PUT INTO OPERATION 27.06/1200 MT
> 1.CONDITION: 11/00 (753) PUT INTO OPERATION 27.06/1200 MT (UTC+0300)
https://www.glonass-iac.ru/en/CUSGLONASS/index.php

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

R11 (R723): 23 June 2016

NAGU message 032-160624:
> 032-160624
> NOTICE ADVISORY TO GLONASS USERS (NAGU) 032-160624
> SUBJ: TRANSFER TO THE RESERVE 11/00 (723) 24.06/0934-24.06/0934 MT
> 1.CONDITION: 11/00 (723) TRANSFERRED TO THE RESERVE
>  SINCE 24.06/0934 UNTIL 24.06/0934 MT (UTC+0300)
https://www.glonass-iac.ru/en/CUSGLONASS/index.php


The updated antenna correction model is available at
ftp://ftp.igs.org/pub/station/general/igs08_1903.atx
or
ftp://ftp.igs.org/pub/station/general/igs08.atx

Many thanks to Stefan Schaer for his help!

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