16 November 1974
Waxing Crescent, 9% lit
A message aimed at 25,000 stars
Arecibo beamed 1,679 bits at the globular cluster M13, and if anyone answers it will be some time after the year 50,000.
The number 1,679 is the product of two primes, 23 and 73, so the only sensible way to lay it out is a grid — a hint that the picture is a picture. It was really a ceremony for the telescope's new surface rather than a serious attempt at contact, and M13 will have moved by the time the signal arrives.
- Date
- 16 November 1974
- Moon computed for
- 17:00 local time, UTC−4
- Phase
- Waxing Crescent
- Illuminated
- 9%
Source: Staff at the National Astronomy and Ionosphere Center, Icarus 26, 462 (1975)