Hook: Wall Large (Purple Rectangle)The Banner: Jedi Temple decoration fits into a large purple rectangle wall hook.
How to Get a Banner: Jedi Temple Decoration
Cartel Pack Decorations
The Banner: Jedi Temple decoration can be dropped from Deep Core Explorer’s Packs, which were released on the Cartel Market and bought with Cartel Coins. Cartel Packs, including the Deep Core Explorer’s Pack, include a random selection of items from the Deep Core Explorer’s collection of items. You aren't guaranteed to get a Banner: Jedi Temple decoration from a Deep Core Explorer’s Pack, but it is one of the few ways to get a Banner: Jedi Temple deco apart from buying it on the GTN from another player.
If you're looking to get a Banner: Jedi Temple, the easiest way to get it is to head to the Galactic Trade Network (GTN) in SWTOR and buy it with credits from another player. If it's very rare and not available on the Cartel Market, you could try buying from the GTN and hope you get it.