Unnamed tagalong 23P4H2V0

Unnamed tagalong 23P4H2V0
x = 10, y = 15, rule = B3/S23 9bo$7b3o$5b2o$5bo2b2o$5bo3bo$6b2o$7b2o$5b2o$5bo2b2o$5b3o2$bo2bo$o$o3bo $4o! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ AUTOSTART ]] #C [[ ZOOM 16 TRACKLOOP 4 -1/2 0 THUMBSIZE 2 GPS 2 HEIGHT 400 ]]
View static image
Pattern type	Tagalong Spaceship
Number of cells	32
Bounding box	12 × 16
Direction	Orthogonal
Period	4 (mod: 4)
Speed	c/2 | 2c/4
Heat	28.5
Kinetic symmetry	n
Discovered by	Hartmut Holzwart
Year of discovery	2020
Rules Outer-totalistic rules B3/S23 – B38/S2378 # of rules 23 = 8 Isotropic rules B3-cr/S23-cy – B2n34ejrt5ce6cn7e8/S234ce5-cjny6-kn78
Glider synthesis Fewest gliders 31† Catagolue-generated RLE synthesis †Can be constructed with 15 gliders using the reverse caber tosser universal constructor.
Pattern files Plaintext 23p4h2v0tagalongonlwss.cells RLE 23p4h2v0tagalongonlwss.rle
Identifiers apgcode xq4_17ojhc6ojszy79ghu

This small, unnamed tagalong was discovered on the 8th of December 2020 by Hartmut Holzwart. It can be attached to any XWSS. The version to the right is this tagalong attached to a lightweight spaceship, resulting in a spaceship with a minimum population of 32. It can also be attached to a heavyweight spaceship in the same manner, as well as to a middleweight spaceship in two different ways, or to itself. One standard spaceship can support two of these tagalongs.

The 32-cell version supported by a lightweight spaceship was the smallest known spaceship with no known glider synthesis until Entity Valkyrie found a recipe for it on February 1, 2025. The "MWSS top" variant was among the smallest remaining spaceships with no known synthesis, until one was found on June 28, 2025, and was the last of the four variants to have a known synthesis

Image	Cells	Supporting spaceship apgcode	Synth. cost
	32	LWSS xq4_17ojhc6ojszy79ghu	31
	34	MWSS back xq4_ra24sz8ajlszy1aghgis	32
	34	MWSS top xq4_g808wsjo6chjo71zf8841	32
	36	HWSS xq4_ra24sz8ajlszy1aghhgis	31

Gallery

x = 24, y = 37, rule = B3/S23 o$4o$3b2o$2o2b2o$obobo$2b2o$bo2bo$o2b2o$bo3bo$b4o$3b2o$7bo$7b3o$10b2o $7b2o2bo$7bo3bo$9b2o$8b2o$10b2o$7b2o2bo$9b3o2$12bobo$12bob3o$17bo$12b ob2ob2o$12bobob2o$14bobo$12bo$15bobo$15bob2o$12b2o2b2o2$20b2o$19b4o$19b 2ob2o$21b2o! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ HEIGHT 350 ZOOM 8 ]]

23P4H1V0 chained to itself (click above to open LifeViewer) RLE: here Plaintext: here