Which star or galaxy is the oldest you have found using your equipment? How old was it?

Question: Which star or galaxy is the oldest you have found using your equipment? How old was it?
- Keywords:
  galaxy,
  space,
  star
Asked by anon-279411 to Tom on 5 Feb 2021.
- Tom Louth answered on 5 Feb 2021:
  
  We are still designing the instrument so haven’t used it to look at anything in the sky yet. Also the telescope it will be used with (the ELT) is still being built! The plan is actually that scientists from all over the world will be able to use the instrument to do whatever science they want. Sorry that doesn’t really answer your question.

Question: Which star or galaxy is the oldest you have found using your equipment? How old was it?