Subaru Night-Sky Spectrograph (SuNSS) - Fiber cable construction

In this paper, we present details about the construction of the fiber cable of Subaru Night-Sky Spectrograph (SuNSS). This instrument addresses two of the major concerns on the PFS project, namely understanding the temporal and spatial behavior of the night sky emission, particularly in the red and infrared channels, and finding a way of accurate night sky subtraction for the fiber spectrographs. SuNSS is installed on the spider arm of Subaru telescope, and can deliver the lights to PFS spectrograph via the fiber cable called FOCCoS-B (Cable B). This means that SuNSS enables us to take sky spectra as long as the dome shutter is open even when PFI is not installed on the telescope. The SuNSS fiber cable consists of two sets of 127 optical fibers in a length of about 1330 mm; uniform-sky fiber set and imaging-sky fiber set. The input side is terminated with 127-fiber hexagonal-array ferrules. The output side is a Tower Connector system with MTPs ferrules, to attached with Cable B and provide light for the fiber slit on Spectrograph following the same coded map as PFS. As PFI does, the fibers to confirm connection are accommodated. Measured FRD was comparable to that of PFI.