[IGSMAIL-6533] igs08_1673.atx: Update including Block IIR-M satellite G049

[David Maggert]

Dear IGS colleagues!

The absolute IGS antenna correction file (igs08_wwww.atx) has been 
updated. The new release is called 'igs08_1673.atx'. It contains the 
following changes:

1) According to 'NANU 2012003' the following satellite has been added:

G24 (G049)

NOTICE ADVISORY TO NAVSTAR USERS (NANU) 2012003 NANU TYPE: GENERAL
*** GENERAL MESSAGE TO ALL GPS USERS *** On approximately 01 FEB 2012 
SVN49 will resume transmitting L-band utilizing PRN24. At L-band 
activation, SVN49/PRN24 will be unusable until further notice. 
Additionally, no broadcast almanacs will include SVN49/PRN24. Future 
NANUs will inform users of any changes to the above-stated status.
http://cgls.uscg.mil/pipermail/nanu/2012-January/001385.html

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

G24 (G024): 30 September 2011

NOTICE ADVISORY TO NAVSTAR USERS (NANU) 2011083
...
GPS SATELLITE SVN24 (PRN24) WILL BE UNUSABLE ON JDAY 273 (30 SEP 2011) 
BEGINNING 1437 ZULU UNTIL FURTHER NOTICE.
http://cgls.uscg.mil/pipermail/nanu/2011-September/001356.html

SVN24/PRN24, a Block IIA satellite launched in 1991 and the second
oldest active GPS satellite, reportedly experienced a reaction wheel
failure on 30 September 2011. It has stopped broadcasting L-band
signals.
https://listserv.unb.ca/cgi-bin/wa?A2=ind1110&L=CANSPACE&T=0&F=&S=&P=926

The updated antenna correction model is available at
ftp://igs.org/pub/station/general/igs08_1673.atx
or
ftp://igs.org/pub/station/general/igs08.atx

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