In Guizhou Province, China, the worlds largest radio telescope is almost complete, measuring 500 metres across.
I am aware that todays largest optical telescope require very accurate figuring and that the longer wavelengths of radio waves allow more leeway in the figure of the dish, but I don't know what degree of tolerance we can "get away with" and still obtain useful data.
My question is: I am sure there a wavelength dependent formula for the accuracy required of the surface and I wonder what it is? Bearing in mind that the:
dish is 500 metres in diameter and the aim of the the telescope will be to search for ancient signals of hydrogen, 21 cm, one of the building blocks of the early Universe - to try to understand how the cosmos evolved. It will also be hunting for new stars - in particular a rapidly rotating and extremely dense type of star called a pulsar - and it will even join the hunt for extraterrestrial life.
In the comments below, CuriousOne was good enough to provide the answer (am I kicking myself? Yes) so if I could refine this question to ask: how great an increase in resolving power does this new telescope potentially have over the 305 m Arecibo telescope? Or is comparing their performance more subtle than that?