Installation of the PFS fiber cable was completed!

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We achieved one milestone in early June 2023. The installation of all the fiber cables has been completed finally!

Among the PFS instruments, the fiber cable system, which consists of about 2400 optical fibers, delivers the light from the prime focus of the Subaru telescope to the Spectrograph Modules. The fiber cables are assembled into four units, each of which is used for one Spectrograph Module.

The fiber cable system was developed by Laboratório Nacional de Astrofísica and Kavli IPMU in collaboration with Durham University. All four units were delivered to Subaru Telescope by June 2022. After it, we have been arranging installation of the fiber cables. The third cable was installed in February 2023, and the forth in June 2023.

As we did for the previous three cables, we installed the fiber cable in two stages. On the first day, the fiber was routed from the prime focus of the telescope to the bottom of the telescope (see the blue star in the above figure). On the second day, the rest of the fiber cable was pulled up to the fourth floor, where the Spectrograph Modules are installed. If the fiber got twisted and/or stressed, the image quality of out-coming light to the spectrograph degraded. To avoid this, the fiber cable was installed carefully checking its orientation (see this article for details).

About 10 people from Subaru DayCrews and the PFS team worked on the installation. The team’s cooperation at various positions was crucial for routing such a long (>50 m) cable.

Day 1: installing the fiber cable on the telescope
Day 2: pulling up the fiber cable

Monitoring the fiber image after installation suggested that the fiber cable had some stress. Therefore, routing was adjusted in late June. We are monitoring the fiber to see if the adjustment has worked.

P.S. It snowed a little when we installed the fiber cable at the end of May..