Empirical Modelling of Thermal Wobbling of Attitude

In Version 1.X processed data, there is a time-dependent attitude wobble of 30-60 arcsec, which is synchronized with the orbital period of the Suzaku satellite (96 min). This is thought to be due to thermal distortion affecting the relative orientations of the scientific instruments and the star trackers. This thermal wobbling significantly broadens the image core and leads to errors in derived source positions.

An empirical correction method has been developed, and coded in the form of a new tool, aeattcor. In Version 2.X processed data, this tool has been run on the attitude file before it is applied to the event data. That is, users of Version 2.X processed data need not take any additional action, while Version 1.X data users can apply this correction by updating the attitude file using aeattcor and applying it to the event files. This method has been verified to sharpen the source images and reduce the source position errors from 60" to 20". More details of the empirical correction can be found in Suzaku Memo 2007-04.