TITLE:   GCN CIRCULAR
NUMBER:  8212
SUBJECT: SGR J0501+4516: radio pulsar searches with GBT and WSRT
DATE:    08/09/10 21:55:36 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@lheamail.gsfc.nasa.gov>

J. Hessels (Univ. of Amsterdam), N. Rea (Univ. of Amsterdam), S. Ransom
(NRAO), B. Stappers (Univ. of Manchester), & collaborators


On 2008 August 23 14:53 (UT) we observed the recently discovered Soft
Gamma-Ray Repeater SGR J0501+4516 (GCN 8112, 8113) with the Green Bank
Telescope (GBT) for about 1 hour, using the Pulsar Spigot at 2 GHz.

Folding the data at the X-ray rotational period of 5.769s (ATEL 1677)
revealed no radio pulsations over a wide range of trial dispersion measures
(DMs).  We place an upper limit of 40microJy on a putative radio pulsar at
this epoch, consistent with synthesis upper limits on the radio counterpart
from earlier that day (GCN 8125).  We have also searched a large range of
DMs for individual bright pulses and bursts. No obvious radio bursts were
found down to a time resolution of 3ms and a maximum DM of 1000 pc/cm^3.

Note that during our observation Swift-BAT observed a large burst (on 2008
August 23 14:56:26 UT; ATEL 1678) for which no obvious radio counterpart was
detected.

We are continuing to analyze these data to search for fainter signals.

Westerbork observations are planned starting on 2008 August 26 03:00 (UT) to
search for pulsations from the recently reported VLA radio counterpart (GCN
8130).
A GBT ToO monitoring program to search for radio pulsations has been
requested.

We would like to thank the GBT schedulers for their prompt attention to our
request for observations.