sheffield weather mast temperatures recorded since 1998

SELECT ?m ?rv ?hv ?t WHERE {
    ?m <uri://opensheffield.org/properties#sensor> <uri://opensheffield.org/datagrid/sensors/Weather_Mast/Weather_Mast.ic> ;
       <uri://opensheffield.org/properties#rawValue> ?rv ;
       <http://purl.oclc.org/NET/ssnx/ssn#hasValue> ?hv ;
       <http://purl.oclc.org/NET/ssnx/ssn#endTime> ?t .
  FILTER (STR(?t) > "2011-09-24T00:00Z")
}
ORDER BY ASC(?t)