[kens]

No, it needed to lock onto the right star, the one that matched the coordinates. Otherwise, it would be pointing in a random direction. The navigator would check against three different stars to detect an error.

The system could also use planets or even the sun for navigation. A special filter was used with the sun to avoid burning out the photomultiplier tube.

[js2]

Ah, so it could be used in the daytime. I read the whole article assuming it was only useful at night. (When else would you be flying a bomber and need high accuracy?)

[teamonkey]

The SR-71’s star tracker was so sensitive it could track stars during the day.

https://theaviationgeekclub.com/the-sr-71-blackbird-astro-na...

[spiritplumber]

being halfway to space probably helped