4.6.2.3 Grating Activities

Grating verification activities cannot begin until Period 2 and each grating insert and retract mechanism must not be operated until the start of their respective grating verification. We do not anticipate the operational verification of the grating insert and retract mechanism to be more than a single insert and retract; this can be done as part of the grating verification. The HETG verification will be performed only with the ACIS-S; likewise, the LETG verification will only be performed with the HRC-S. Grating verification will consist of observing celestial targets and analyzing the data from the FPSI for the expected performance.