There has been some confusion as to the orientation of the f/25 guider, the NIRC detector and the chopper. See f/25, Guider, NIRC and Chopper Orientations is the current best estimate. Note that this is consistent with See f/25 IR Frame (KI) (looking toward the sky) .
It should also be noted that the f/25 rotator zero point was determined to be in error by 1.2 deg at a recent LWS run. The new zero point was used for a subsequent NIRC run, as a result of which the "2.12" of See f/25, Guider, NIRC and Chopper Orientations was observed to change to "0.9". Given that the "0.52" was measured using NIRC and the guider, a rotator zero point change should not have affected it. However, NIRC offsetting was very unreliable and the old rotator zero point has been restored for NIRC pending further investigation.