Ah. A picture of a Cleveland Guardian
Fallout?
Ahhhh...the TV test pattern!
I remember The TV Man using it for tuning our TV during his annual house call.
And, on some channels (we had five), it went on at midnight when they signed off for the night, right after they played High Flight:
An article on the High Flight sonnet:
https://blogs.loc.gov/catbird/2013/09/john-gillespie-magees-high-flight/