TITLE:   GCN CIRCULAR
NUMBER:  21084
SUBJECT: LIGO/Virgo G284239: H.E.S.S. very-high energy gamma-ray follow-up
DATE:    17/05/10 13:23:20 GMT
FROM:    Fabian Schussler at HESS Observatory  <fabian.schussler@cea.fr>

M. de Naurois on behalf of the H.E.S.S. collaboration

The H.E.S.S. array of imaging atmospheric Cherenkov telescopes was used to carry out follow-up observations of 4 regions within the LIB map of the GW trigger G284239.
Observations started May 4, at 02:01 UT and resulted in a sensitivity (above ~100 GeV) of about 20% of the flux from the Crab nebula at 5 sigma throughout the covered region. A preliminary analysis did not reveal significant gamma-ray emission in any of the observed fields (within a field-of-view of ~2deg radius around the coordinates given below). Further analyses of the data are on-going.

The following region-of-interests (ROIs) were observed:

ROI 1:
Target RA	18h01m14s
Target Dec	-17°44'24''
Duration: 22 min

ROI 2:
Target RA	18h27m50s
Target Dec	-28°42'36''
Duration: 28 min 

ROI 3: 
Target RA	18h14m29s
Target Dec	-19°36'0''
Duration: 28 min 

ROI 4: 
Target RA	18h34m7s
Target Dec	-30°48'36''
Duration: 19 min

H.E.S.S. is an array of five imaging atmospheric Cherenkov telescopes for the detection of very-high-energy gamma-ray sources and is located in the Khomas Highlands in Namibia. It was constructed and is operated by researchers from Armenia, Australia, Austria, the Czech Republic, France, Germany, Ireland, Netherlands, Japan, Poland, South Africa, Sweden, UK, and the host country, Namibia.