How does FUSE find the stars and galaxies it is supposed to point at?
A timeline of observations is scheduled on the ground and uplinked to the satellite. However, actually pointing the telescope in the right direction and locking onto the objects of interest is something we have taught FUSE to do for itself! It takes coordination between the computer on the “spacecraft” and the computer in the telescope itself, as well as information provided by the Fine Error Sensor (FES) guide camera. Coarse pointing, to about 2 degrees accuracy, can be done by the spacecraft itself using its gyroscopes and devices called magnetometers. But 2 degrees is still 4 times the size of the full moon, a pretty big area on the sky! The FES camera takes pictures, and by identifying the stars we see, we can find EXACTLY where we are pointed! Once we know where we are, we can tell FUSE to move to a new position and find another set of expected stars, including the object we want it to observe in ultraviolet light. And so it goes. Now the clever reader will notice that, although t
