The following p4 oscillator with a minimum population of 52 cells. Discovered by Josh Ball.

beacon.png

x = 20, y = 20, rule = s0/b2
6bo6bo$5bo8bo$8bo2bo$7bo4bo2$2bo6b2o6bo$3bo4bo2bo4bo$o6bo4bo6bo$bo4b2o
4b2o4bo3$bo4b2o4b2o4bo$o6bo4bo6bo$3bo4bo2bo4bo$2bo6b2o6bo2$7bo4bo$8bo
2bo$5bo8bo$6bo6bo!