Medusa

Period-28 glider gun
x = 81, y = 54, rule = B3/S23 40bo3b2o$39bobobo2bo$39bobob2obo$15b2ob2o17b2o2bobo2b2o13b2ob2o$14bobo bobob2o14bobobob2o11b2obobobobo$14bobo3bobo2bo11bo2b2o3bo9bo2bobo3bobo $12b2o2bo3bo3b2o11bobo3b2o10b2o3bo3bo2b2o$13bobo5bo16bob3o2b3o11bo5bob o$13bob7o17bo4bo2bo11b7obo$12b2o4bo21b3obobo15bo4b2o$11bo2b3obob4o10b 2o8bob2o9b4obob3o2bo$11b2o3bo3bo2bo11bo2b4o2bo12bo2bo3bo3b2o$17b3o6b2o 7bobo4bobo8b2o6b3o$17b3o6bo9bobobob2o10bo6b3o$18bo9bo9bobo11bo9bo$19bo 7b2o8bob7o6b2o7bo$14b2o2b2o4b2o9b3o7bo9b2o4b2o2b2o$14bo2bo6bob5o3bo3bo b2obo6b5obo6bo2bo$15b3o3b2obo4bobo3bobo3b7obobo4bob2o3b3o$12b3o5bobobo 2bo3bo2b2ob3o7bobo3bo2bobobo5b3o$12bo2b3o6bo3b4obo10b2o3b4o3bo6b3o2bo$ 14bo3b3ob2ob3o5bob3o7bobo5b3ob2ob3o3bo$15b2o6bobo4b3obo2bobob2o2bob4o 4bobo6b2o$17b5obobo2b2o4bo3b2ob2o3bo4b2o2bobob5o$17bo4b2obob3ob3o5b3o 5b3ob3obob2o4bo$20bo4b3o2bo19bo2b3o4bo$19bob4o6bo8bo8bo6b4obo$19bobo3b 3o4bo7bo7bo4b3o3bobo$20bo3bo2bob2obo6bobo6bob2obo2bo3bo$24b2o2bo3bob2o 9b2obo3bo2b2o$11b2o16b3obobo9bobob3o16b2o$11bo5bo13bobobob7obobobo13bo 5bo$4b2o2b2obobo2bobo9bobo2bo3bo2bo2bo3bo2bobo9bobo2bobob2o2b2o$4bo3bo bob5obo8b2o3bo2bobo5bobo2bo3b2o8bob5obobo3bo$b2obo5bo7b2o2b2o3b4o4b2o 7b2o4b4o3b2o2b2o7bo5bob2o$obob2o4b2ob3obo4b2ob2o3b3o2b11o2b3o3b2ob2o4b ob3ob2o4b2obobo$obo4bo5bo3b2ob4o3b3obo5b7o5bob3o3b4ob2o3bo5bo4bobo$bob 3o3bo5bo5bo2b2o4bo19bo4b2o2bo5bo5bo3b3obo$2bo2bob3ob2o4b2obo2bobob2obo b2o13b2obob2obobo2bob2o4b2ob3obo2bo$3b2o7bo5bob4obobo2bo2bo5b3o5bo2bo 2bobob4obo5bo7b2o$5b6obobo3bo7bo2bobo7bobo3bobo2b2o2bo7bo3bobob6o$5bo 2bo2bob2o4b3o8bo8b3o3b2o12b3o4b2obo2bo2bo$11bo9bo11b2o24bo9bo$10b2o21b o35b2o$30b2obo10bo$30bob2ob2o8bo$35bo7b3o$35bo$32b2ob2o$32bobo$34bo5b 2o$34b2o4bo10bo$41b3o8bo$43bo6b3o! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ AUTOSTART ]] #C [[ ZOOM 4 AUTOSTART GPS 7 LOOP 28 ]]
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Pattern type	Gun
Number of cells	831
Bounding box	81 × 54
Period	28
Barrels	1
Discovered by	Matthias Merzenich
Year of discovery	2020
Rules Outer-totalistic rules B3/S23 only # of rules 20 = 1 Isotropic rules B3/S23 – B37c/S23
Pattern files Plaintext period28glidergun.cells RLE period28glidergun.rle

Period-28 glider gun was the first true period 28 gun to be found. It was discovered by Matthias Merzenich on December 15, 2020. A more compact form was posted by Merzenich later that day. The reaction that produces the glider was found by Paul Callahan and Merzenich in May, 2013.