Nowadays, for most people UV filter = protection filter and vice-versa.
Interesting about the astro stuff but surely for that you would remove the filter anyway?
However, I am now branching out into basic wide field imaging of the sky i.e. DSLR + lens on a tripod using a lightweight Vixen Polarie tracking mount. For this purpose I want the light (photons) as they arrive and certainly not taking out the UV but with a clear protector filter on the front of the lens for when the dew comes down, as it inevitably does.
All modern cameras have built in UV filters over the front of the sensor anyway so it doesn't make much difference if you have a UV filter or clear protector, hence the terms are often used interchangeably.
I'd love to live somewhere this type of photography is possible, it's just too bright around me and every time I've travelled somewhere dark in the UK it's been cloudy
It's not very windy there though!I'm off to the Grand Canyon = sand!