Who Chose the CMB Temperature?

• Looks suspiciously like e Kelvin (=2.718281828 K).
• Is it the triple point of water divided by 100 (=2.7315 K)?
• Could it be precisely 30/11 Kelvin (=2.727 K)?
• What about -ln(9 α) Kelvin (=2.723 K)?
• Or perhaps √(15/2) Kelvin (=2.739 K)?
• How about (2 α/π)⁴ m_ec²/k (=2.762 K)?
• Or maybe (2/5) (α_Gm_e / 2π m_p)^1/4 m_pc²/k (=2.719 K)?
• Or even (4/π) α^-3 α_G^1/2 m_pc²/k (=2.741 K)?
• Or even better 16 √2π α_G^1/4 m_ec²/k (=2.727 K)?
• Or closer still (45/2π⁴)^1/4 α_G^1/4 α^-3/4 (m_e/m_p)^3/8 m_ec²/k (=2.7254 K)?
• Or in terms of Planck units, what about e^-73T_Pl (=2.805 K), where T_Pl=√(ħc⁵/G)/k ?
  • [and e^-73 is close to e^-πeπ]
• Or turning to imperial units such as the League (=3 miles), how about hc/k (µL)^-1 (=2.98 K)?

Interested surfers with nothing better to do might like to think of reasons why the CMB is at -270.425° Celsius or -454.765° Fahrenheit.