[IGSMAIL-6771] igs08_1739.atx: SVN49 switched from PRN27 to PRN30

[Ralf Schmid]

Dear IGS colleagues!

The absolute IGS antenna correction file (igs08_wwww.atx) has been 
updated. The new release is called 'igs08_1739.atx'. It contains the 
following changes:

1) According to NANU 2013029 BLOCK IIR-M satellite SVN49 continued 
"transmitting L-band utilizing PRN30 on approximately 08 May 2013". 
Therefore, the following satellite has been added to igs08.atx:

G30 (G049)

In fact, IGS stations started tracking SVN49/PRN30 on 9 May 2013 (DOY 
129) according to the IGS tracking statistics provided by CODE 
(ftp://ftp.unibe.ch/aiub/igsdata/odata_gnss_day.txt). As SVN49 was still 
active as PRN27 the same day, the start date of SVN49/PRN30 in igs08.atx 
is 10 May 2013.

Source:
> NOTICE ADVISORY TO NAVSTAR USERS (NANU) 2013029 NANU TYPE: GENERAL
> *** GENERAL MESSAGE TO ALL GPS USERS *** On approximately 08 May 2013 SVN49 will continue transmitting L-band utilizing PRN30. SVN49/PRN30 will remain unusable until further notice. Additionally, no broadcast almanacs will include SVN49/PRN30 until further notice.
http://cgls.uscg.mil/pipermail/nanu/2013-May/001500.html

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

G27 (G049): 9 May 2013
G30 (G035): 6 May 2013

Although officially removed from the GPS constellation on 1 May 2013, 
SVN35/PRN30 didn't stop signal transmission before 6 May 2013 according 
to the IGS tracking statistics provided by CODE 
(ftp://ftp.unibe.ch/aiub/igsdata/odata_gnss_day.txt). PRN27 will be 
utilized by GPS IIF-4 to be launched on 15 May 2013.

Sources:
> NANU 2013027
...
> GPS SATELLITE SVN35 (PRN30) WAS UNUSABLE AS OF JDAY 087 (28 MAR 2013)
>     AND REMOVED FROM THE GPS CONSTELLATION ON JDAY 121 (01 MAY 2013).
http://cgls.uscg.mil/pipermail/nanu/2013-May/001498.html

> Upcoming GPS Block IIF-4 Launch
...
> The IIF-4 satellite, also known as SVN66, will operate as PRN27.
> SVN66/PRN27 will eventually occupy the C-2 slot, replacing
> SVN33/PRN03, a Block IIA satellite launched in 1996. Reportedly,
> SVN66/PRN27 will go through an extended period of testing following
> launch, and is not expected to be set healthy until August. SVN33 will
> become a reserve or backup satellite.
https://listserv.unb.ca/cgi-bin/wa?A2=CANSPACE;8ff1bac1.1305

3) Spikes (< 0.4 mm) have been removed from the GLONASS phase center 
variations of two further antenna types:

LEIAT504GG      LEIS
TRM55971.00     TZGD

For further information please refer to [IGSMAIL-6753]:
http://igscb.jpl.nasa.gov/pipermail/igsmail/2013/007943.html


The updated antenna correction model is available at
ftp://igs.org/pub/station/general/igs08_1739.atx
or
ftp://igs.org/pub/station/general/igs08.atx

Thanks to Richard Langley for his help as regards SVN49 and to Stefan 
Schaer for detecting further spikes in igs08.atx GLONASS calibrations.

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