The Soviet Cosmonaut Training Centre had the code name Military Unit 26266 and was also known by the initials TsPK (Tsentr Podgotovki Kosmonavtov).
Notes on verification
Corroborated by official GCTC website, Russian and English Wikipedia, and secondary sourcing referencing Burgess & Hall's historical account. Multiple independent sources converge on both the military unit designation and TsPK acronym.
Sources
- How Yuri Gagarin Was Picked to Be First in Space (smithsonianmag.com)
- http://www.gctc.su/main.php?id=242 (gctc.su)
- https://military-history.fandom.com/wiki/Yuri_Gagarin_Cosmonaut_Training_Center (military-history.fandom.com)