TO:  GCN Customers
DT:  21 Jul 07
RE:  Outage of Swift-to-GCN Operations

This morning (10:01:08 and 10:33:48 UT) there were two Swift-BAT
triggers (285653 and 285654) which at first glance appear
to be real GRBs.  However, there was a problem in the connection
between the front-end part of GCN (swift_tdrss_receiver) and
the main GCN program (gcn_main) which prevented the Swift
GCN Notices from being distributed to the regular customer list.

This problem has been elimited.  Normally, the parts of the GCN
system that monitor this (and other) connections was not able
to clear the problem and re-establish the connection. This loss
of connection occurs at the 2 or 3 times a year level, and the
automated reconnection monitor works within 4 minutes after
the start of the loss of connection.  However, this time it did not
succeed.  And to further compound the problem, the automated 
notification (to me) of this connection problem did not work.
Hense the outage was allowed to continue without human intervention.

Peliminary investegations show that the connection was in a partial
state.  The connection state was sufficient so as to not trip
the connection monitor, but was not fully connected to allow
the passage of data from the front-end program to the main program.
This new scenario will be futher investigated and a solution will
be found to prevent this new type of loss-of-service problem.

This problem affected only the Swift-related Notices.  All the other
GCN Notice types were and continue to function normally.  Nor did
it affect the Circulars.

I apologize for the loss of these two bursts.

The Swift team is waiting for the downlink of the full data sets
and will have the usual "refined analysis" circulars on these
two triggers.

Again, I apologize.  GRBs are a rare commodity, and to loose two 
of them is serious and intolerable loss to the scientific community.

Sincerely,
Scott Barthelmy

Scott Barthelmy                      NASA-GSFC, Code 661, Greenbelt, MD   20771
PHONE:  301-286-3106                 (work)
CELL:   301-346-3733
FAX:    301-286-1684                 (1st choice,  -1682 2nd choice)
EMAIL:  scott@lheamail.gsfc.nasa.gov
PAGER:  3013463733@cingularme.com    (send short email to this address)
WEB:    http://gcn.gsfc.nasa.gov/gcn