gistfile1.rb

require 'TZInfo'

today = Time.now
(0..23).each do |hour|
  (0..45).each do |minute|
    utc_time_to_check = Time.utc(today.year, today.month, today.day, hour, minute, 0)
    TZInfo::Timezone.all_identifiers.each do |zone_name|
      local_tz = TZInfo::Timezone.get(zone_name)
      local_time = local_tz.utc_to_local(utc_time_to_check).to_datetime
      if local_time.minute == 0 && local_time.hour == 8
        puts utc_time_to_check.strftime("%H:%M") + ' UTC => ' + local_time.strftime("%H:%M") + ' in ' + zone_name
      end
    end
  end
end