Pointing reconstruction

During the flight, the gondola pendulates and does not rotate at constant speed, we therefore have to reconstruct off line the direction pointed by each bolometer for each sample. This is done using a stellar sensor telescope that is attached to the gondola and points in the same direction as the bolometers. The stellar sensor focal plane contains 48 photodiodes whose signal exhibits a peak whenever they cross a star. We therefore obtained an observed star catalog that is compared with a real one in order to give the pointing solution. Our pointing accuracy is estimated to be around one arcminute.