Astrophysics (index)about

low frequency radio astronomy

(LF radio astronomy)
(astronomy using the lower end of the radio spectrum)

Low frequency radio astronomy (or LF radio astronomy) obviously refers to using the lower frequency portion of radio, but the terms are not used consistently regarding a threshold: I assume there are groups that use the term differently.

350MHz, or something in that region seems common: in other words, essentially everything lower-frequency than microwave, which includes much of what is termed radio astronomy. For example, Low-frequency Array senses up to 240MHz.

But the term has been used for the lower-frequency end of this range: I've seen 30MHz cited, which is not far above the low-frequency end of the radio atmospheric window, and much lower could require a space observatory.