Fixed older pieces to a huge observational instrument (5,9)

I believe the answer is:

radio telescope

I'm a little stuck... Click here to teach me more about this clue!

'huge observational instrument' is the definition.
'radio telescope' can be an answer for 'instrument' (radio telescope is a kind of instrument). I am unsure of the 'huge observational' bit.

'fixed older pieces to a' is the wordplay.
'fixed' indicates an anagram.
'older'+'pieces'+'to'+'a'='olderpiecestoa'
'olderpiecestoa' anagrammed gives 'RADIO TELESCOPE'.

Can you help me to learn more?

(Other definitions for radio telescope that I've seen before include "Astronomical instrument" , "scientific equipment" .)

I've seen this clue in The Telegraph.

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