Disk covering problem $r(8)$

The smallest value $r(8)$ such that $8$ disks of radius $r(8)$ can be arranged to cover the unit disk.

Updates

• Upper bound: ${\approx}0.445041$
  Reference unknown
  [via Circles Covering Circles, Erich Friedman]
• 1996 Lower bound: ${\approx}0.445041$
  Gábor Fejes Tóth in 1996
  [via Circles Covering Circles, Erich Friedman]