Jango doesn’t realize there’s a tracking device on his ship until he’s near the planet, and once he believes Obi Wan was asteroid chow, may have assumed that the Jedi had no time to report his position.
Right, but he technically doesn’t even need to know what his part in the plan is. Dooku could have told him ‘Jango, if the Jedi start snooping around, come find me on Geonosis.’ He says to the Geonosians that the Republic is ‘treacherous’ for raising an army, but he’s all smiles about it with Sidious.