From the looks of it, it seems to be a security light. Which could be an HID or HPS system. Although if it's a flood or security light, i think it'll put out a ton of heat, so if you use it, keep it a good distance from the plants.
look like a 250 or 400 hps ,,,,looks more like 250 ,,,,,good luck ,,,,,,,,,,,,,,,,,sorry i looked at it again that may be a big one 1000watts maybe what ever it is it will work