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From: stefan.schaer@swisstopo.ch
To: igsmail@igscb.jpl.nasa.gov, eurefmail@oma.be
Subject: [IGSMAIL-5199]: NRT data flow problem caused by DC outage
Date: Thu, 1 Sep 2005 08:58:39 +0200 
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IGS Electronic Mail      31 Aug 23:58:44 PDT 2005      Message Number 5199
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Author: Stefan Schaer


Dear IGS/IGLOS/EUREF colleagues,

We would like to point to a problem that (once more) became obvious
thanks to the recent DC outage at BKG:

http://igscb.jpl.nasa.gov/mail/igsmail/2005/msg00119.html

This DC outage revealed a dramatic impact on the IGS/IGLOS/EUREF NRT
data flow. At CODE, we suffered particularly from the reduced IGLOS data
flow, which makes ultra-rapid (as well as rapid) GPS/GLONASS-combined
POD (unnecessarily) more difficult, if not impossible.

We think a list of affected stations might help to prevent similar data
flow blackouts in the future.

The following list includes all stations for which hourly files were
made available at BKG on day 242 (for the hours prior to the outage):

http://www.aiub.unibe.ch/download/igsdata/bkg_outage_nrtdata.txt

Stations that remained "unaffected" by the BKG DC outage are indicated
with "OK". Stations for which NO hourly observation data could be
found at any DC (during the DC outage) are indicated with "data flow
INTERRUPTED". A compiled list of these "BKG-dependent" stations may be
found at:

http://www.aiub.unibe.ch/download/igsdata/bkg_outage_nrtdata_interrupted.txt

In total, 35 of 147 hourly stations were directly affected by this
several hours lasting DC breakdown (more specifically: 29 of 85 IGS
stations, 16 of 30 IGLOS stations, and 21 of 119 EUREF stations found at
the BKG DC). All these 35 stations seem to consider just one DC
(obviously BKG) for hourly (and daily?) file upload. It is worth
mentioning that 5 of the affected stations even have the status of an
"IGb00" fiducial site (used for datum definition):

hofn
joze
lhas
trab
wtzr

To avoid misunderstanding, here we address a station-related, not a
DC-related problem. According to "IGS/EUREF Site Guidelines", GNSS
observation stations must consider a secondary DC for backup.

Best regards,

Stefan Schaer