Selv wrote:

>what is the origin of "Lokabrenna" being the Icelandic word for
>Sirius? it's mentioned in Grimm's _Teutonic Mythology_, but he makes no
>indication of an Old Norse origin, but just as the modern name. I was
>wondering if you knew how far that went back?

I saw the same discussion and looked the word up as you're suggesting:)
I don't have the etymological dictionary at hand but I think it said the word
was from the 18th century - and then didn't give any sources...

It might be from one of the "dirty" Eddas.

Remember that even if a word occurs only in a late ms it can still be
very old. The whole of Sonatorrek ONLY occurs in a 17th (or was it
18th?) century manuscript and is still accepted as authentic.

Regards,
Haukur