We would like to inform you about the situation after the fourth report (November 23, 2023 Hawaii local time) as follows.
１. Status of countermeasures against "abnormal reading of load sensors at the fix points of primary mirror"
In order to replace the load sensors at the fixed points, we formulated a plan regarding specific work contents and procedures, installed scaffolding, arranged and prepared tools, established the replacement procedure, and estimated the hazards and risks. Then we just started the replacement of the three sensors one by one. The replacement work and post-replacement inspection and evaluation are expected to take several weeks each.
If the reading of the force sensors is restored to the nominal values after the replacement, the repair works would be supposed to be completed. In this case, we will check the telescope performances where we evaluate the telescope pointing accuracy, and the shape of the primary mirror surface. Once we confirm the required performances, it means the completion of the countermeasures.
On the other hand, if the reading is not restored to nominal values even after replacing the force sensors, there may be a problem other than the force sensors. In this case, further investigation will be conducted to identify the location of the problem.
２. Status of response to "damage on the primary mirror"
There are no changes from what we previously confirmed, and as reported before, we plan to repair the damage on the primary mirror after replacing the force sensors.
We sincerely apologize for the long period of telescope shutdown that causes the loss of your observing opportunities. We will continue to update information on our website about once a month.
(Relevant Links)
Regarding the Suspension of Subaru Telescope Night Observation (4th Report)
Regarding the Suspention of Subaru Telescope Night Observation (3rd Report)
Suspension of Night Observations (2nd Report)
Suspension of Night Observations (1st Report)
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