Karel's p177 (or 104P177) is a period-177 oscillator discovered by Karel Suhajda in June 2007. In terms of its minimum population of 104 cells, it is the smallest known period 177 oscillator. It can serve as a 90° or 180° degree reflector in many ways, and with the correct phasing, a glider can pass through it unharmed. On March 21, 2009 Jason Summers found a 24-glider synthesis of this oscillator.
- 104P177.1 at Heinrich Koenig's Game of Life Object Catalogs