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