These objects have fundamentally different spectral shapes in the mid-infrared. Because of this, different problems in the calibration process will affect different object types in varying degrees. The brightness of a source and the speed at which it was observed also influence which calibration issues dominate and which are relatively unimportant. For example, bright stellar sources are affected by memory effects in Band 2, but weak stellar sources are generally well- behaved. Intrinsically red sources, on the other hand, such as planetary nebulae or star forming regions, can be influenced by memory effects in Band 4 as well as Band 2.
Extended sources are more susceptible to pointing issues than point sources.
We will discuss these and other issues related to the type of object observed. Home Library Last modified 17 January, 2001.