That is a good signature from Agartha Market's primary public key. Don't take my word for it though. Log into Agartha through a source you trust. Perhaps on the Agartha subdread (not positive they have one). Darkdotfail works too. Once logged into Agartha, visit the Info/Help page in the menu bar. At the bottom of that page you'll find the exact list of links found in that paste along with the market's public key. You can then check the sig yourself.