This task determines the position and orientation of the SED slit relative to the PCRS.
The goal of this task is to estimate the location of the SED prime frame with repsect to the telescope boresight. However, we do not observe at the prime frame, we use the CSMM with a chop amplitude of at least 1 arc minute peak to peak or +/- 0.5 arc minutes from the central mirror position that defines the "on" beam.
The location of the MIPS instrument frames are found in the frame tables and are given as brown angles. In order to estimate the instrument pointing frame (IPF), a combinations of spacecraft moves and mirror motions places the star on several locations on the array. In addition, these observations are "sandwiched" between observations of stars with the two PCRS. The MIPS team calibrates data and centroids the star on the slit. These centroided values are passed to the IPF team who uses observations of stars with the PCRS to provide the final calibration and estimate brown angles need to locate the instrument frame.
Determining the location of the y centeroid - peak flux - was tricky. The star was only detected in the last position as we stepped across the slit.
The results from the IPF team recommended the following changes to the brown angles for the prime frame : delta_theta_Y (0.0269 arc minutes), delta_theta_Z (1.502 arc minutes), delta_angle (0.000044 degrees). The IPF team gave an accuracy of the locating the prime frame center as 26.4392 arc seconds. The requirement was 1.15 arc seconds. The large correction for the theta_z angle was a result of an incorrect orginal frame table. The results of this analysis were used to update frame table 10. The incorrect frame table was a result of the misunderstanding of the mirror commanding for SED mode. It was thought that the mirror positions were centered about the SED mode, but they are commanded so as not to run into the hard stop.
For a complete summary of frame table updates see:
Frame Table Updates
The values used for frame table 10 are given below.
