keywords = ["2026-08-08 23:","2026-08-08 22:","2026-08-08 21:"]
File.open("extract81.txt", "w") do |out|
  File.foreach("satnogs.csv") do |line|
    if keywords.any? { |keyword| line.include?(keyword) }
      out.write(line)
    end
  end
end