GCN Circular 1372

K. Hurley and T. Cline, on behalf of the Ulysses GRB team,

I. Mitrofanov, D. Anfimov, A. Kozyrev, M. Litvak, and A. Sanin, 
on behalf on HEND/Odyssey GRB team,

W. Boynton, C. Fellows, K. Harshman, C. Shinohara, and R. Starr, 
on behalf of the GRS/Odyssey GRB team, report:


The Mars Odyssey (MO) mission (mars.jpl.nasa.gov/odyssey/), launched in
April 2001, has now been incorporated into the Third Interplanetary
Network.  MO has two instruments with GRB detection capability, the
Gamma-Ray Spectrometer and the Russian High Energy Neutron Detector
(grs.lpl.arizona.edu/instruments/ and
www.iki.rssi.ru/hend/index.html).  HEND has now detected over 30
confirmed cosmic and SGR bursts.  In particular, four events whose
precise positions are known from measurements at other wavelengths have
served to verify the timing accuracy.  The dates of these bursts were
010625 (SGR1900), 010702 (SGR1900), 011121, and 020305.  The first two
occurred during the cruise phase, and the last two during the orbital
phase of the mission.  For each burst, the timing was verified to
different precisions, the accuracies  of the best cases being
approximately 90 ms. While it would be desireable to have further
confirmations, as well as ones with better precision (the spacecraft
timing is accurate to several 10s of milliseconds in principle, and
this can be verified for bursts with the appropriate time structure),
we have proceeded to the next phase of operations.

In this phase, we will issue GCN notices for cosmic and SGR bursts,
incorporating a conservative estimate of the systematic timing
uncertainty timing based on the four existing measurements.  Initially
this will result in somewhat larger error boxes than would normally be
produced by the network.  As counterparts are identified for these
bursts, and smaller uncertainties can be established, they will be used
in place of the previous ones.  


We will also reinstate a supplementary notification service which was
in effect for the period when NEAR was in the IPN, which allows
observers to be notified of bursts with short pager messages.  As soon
one or more spacecraft in the network detects an event which has a good
probability of being localized to a single error box, a notice will be
sent out with all the information available up to that point (e.g.
date, time, duration, intensity, any preliminary location information,
etc.).  Updates will be sent out up to the time a GCN notice is
issued.  Even if you registered for this service in the past, we
request that you re-register now by sending an e-mail to
khurley@sunspot.ssl.berkeley.edu, including your name, your e- mail
address, your pager address (which must be accessible via e-mail), and
the number of characters that can be transmitted to it.

For information on expected burst rates and localization delays, see
ssl.berkeley.edu/ipn3/statusreport.htm.