code: def find_observatories(self, match=None):
          
          url = "%s/gwf.json" % _url_prefix
          response = self._requestresponse("GET", url)
          sitelist = sorted(set(decode(response.read())))
          if match:
              regmatch = re.compile(match)
              sitelist = [site for site in sitelist if regmatch.search(site)]
          return sitelist
docs: Query the LDR host for observatories. Use match to
          restrict returned observatories to those matching the
          regular expression.
  
          Example:
  
          >>> connection.find_observatories()
          ['AGHLT', 'G', 'GHLTV', 'GHLV', 'GHT', 'H', 'HL', 'HLT',
           'L', 'T', 'V', 'Z']
          >>> connection.find_observatories("H")
          ['H', 'HL', 'HLT']
  
          @type  match: L{str}
          @param match:
              name to match return observatories against
  
          @returns: L{list} of observatory prefixes