Reason for change (UPDATE)
Following an analysis of the unbinned photons above 3 GeV, it appears to actually be a fixed offset
see this link
As a follow up to the C&A meeting where I presented the results of pass6/pass7 boresight comparison, it appears that the alignment has changed by 60 arcseconds since the alignment was first determined during L&EO. In particular, the alignment seemed to change over the period from December to February the most significantly. I propose that one set of boresight alignment calibrations should be split up as follows:
September-December (242149417-252517417)
January (252517417-255109417)
February (255109417
Since there are already alignment constants in the reprocessing, it would be easier just to reference the relative changes:
(242149417-252517417): delta-Rx=+11 delta-Ry=+54 delta-Rz=+4
(252517417-255109417): delta-Rx=-33 delta-Ry=+79 delta-Rz=+31
(255109417 : delta-Rx=-31 delta-Ry=+25 delta-Rz=+11
Here is the plot from the C&A meeting:
Test Procedure
The pointlike boresight alignment analysis will be run locally to verify the constants have been applied correctly.
Rollback procedure
CCB Jira
SSC-207@JIRA