A simple graphic consisting of 73 rows of 23 “bits” per row. This number of rows and columns was chosen because each is a prime number. Prime numbers could be easily guessed by any recipients, and that would help them to decode the graphic. The message was sent by simple shifting of the signal between two frequencies in the 2,380 MHz band. It took three minutes to send the message.
The message itself gives the kind of information that any culture would want to learn about us: where we are located (at least within our solar system), what we look like (a crude stick figure), a simple drawing of the telescope used to send the message, and something about our biological construction (DNA and some of the building blocks of our biochemistry.) This message was sent as a “demonstration” to commemorate the upgrading of the 1,000 foot diameter Arecibo telescope with a new, more accurate reflector surface.