Time-lapse videos showcasing the construction process of the prototype Schwarzschild-Couder Telescope.
The installation of the secondary mirror (M2) on the telescope took place from July to August 2018. M2 consists of 24 panels of two types (8 inner ring and 16 outer ring). Each mirror panel module is comprised of a custom-manufactured mirror panel and elements of the alignment system, such as edge sensors and actuators. The mirror panels of M2 are highly aspheric and have a sag of several centimeters. They were fabricated via a two-stage process. First, thin glass sheets were pre-shaped to the approximate required figure using the hot glass slumping technique at FLABEG FE GmbH in Germany. Pre-shaped glass sheets were delivered to Media Lario S.r.l. in Italy, where they were assembled into mirror panels via a cold glass slumping process similar to that used for the fabrication of the M1 panels. The coating of the secondary mirror panels was done by ZAOT S.r.l. in Italy and delivered to the U.S. The parts of the mirror panel alignment system were fabricated by Share Machine Inc. in the U.S. They were assembled into Stewart platforms (hexapods), integrated with the mirror panels, augmented with electronics, and calibrated at UCLA. Finally, the complete M2 mirror panel modules were delivered to Fred Lawrence Whipple Observatory (FLWO) and installed on the pSCT.
The installation of the camera took place from May to June 2018. The prototype camera of the pSCT contains 25 front-end electronics (FEE) modules with 64 photon-detecting sensors (pixels) in each. Sixteen FEE modules were assembled at participating U.S. institutions and nine were delivered by the INAF institutions in Italy. The camera photon sensors are silicon photomultipliers (SiPMs) designed and manufactured by Hamamatsu Photonics and Fondazione Bruno Kessler. The pSCT camera mechanical system was designed at and procured by the University of Chicago. The main pSCT camera integration activities took place at the University of Wisconsin, Madison. The current prototype SCT camera has a total of 1,600 imaging pixels with an angular size of 0.067°, which is more than the number of pixels in three VERITAS telescopes (each VERITAS telescopes is comprised of 499 pixels with an angular size of 0.18°). The fully instrumented 8° field of view SCT camera will contain 11,328 pixels (in 177 FEE modules of 64 pixels each).
The primary mirror (M1) was installed on the telescope from December 2017 to April 2018. It consists of 48 mirror panel modules (MPMs) of two types (16 inner ring, 32 outer ring). Each MPM includes a mirror panel and an associated alignment system consisting of a Stewart platform (hexapod) and edge sensors to allow it to be aligned with its neighbors. Each MPM is equipped with a controller and microcomputer which gathers information from the edge sensors and controls the motion of the MPM's actuators. The primary mirror panels were custom-fabricated by Media Lario S.r.l. in Italy using a cold glass slumping replication technique developed by the company in collaboration with Brera Astronomical Observatory. The coating of the M1 mirror panels was done by Bte Bedampfungstechnik GmbH in Germany, while the parts for the Stewart platforms were machined at Share Machine Inc. in the U.S. Finally, the MPMs were assembled and calibrated at UCLA prior to their delivery to Fred Lawrence Whipple Observatory (FLWO) and installation onto the telescope.
The optical support structure (OSS) of the pSCT was designed at Argonne National Laboratory and manufactured by Walters Metal Fabrication in the U.S. It was delivered to Fred Lawrence Whipple Observatory (FLWO) in early spring 2016. The OSS assembly and its installation on the pSCT tower was done by FLWO personnel from May to August 2016.
The telescope tower and positioning system of pSCT was designed by the team at DESY, Zeuthen in Germany. The components were fabricated in Europe, preassembled at DESY, Zeuthen, and shipped to Fred Lawrence Whipple Observatory (FLWO). The positioner tower and telescope motion system was installed at the pSCT foundation by DESY engineers and FLWO personnel from February to April 2016.
The pSCT is constructed on the foundation previously used for the VERITAS prototype telescope at the Fred Lawrence Whipple Observatory (FLWO). To accommodate the 80 ton weight of the pSCT, it was necessary to reinforce the original foundation. This work was conducted from June 2015 to January 2016. During the same period, all infrastructure elements such as conduits, the foundation for the camera chiller, and the electrical distribution shed, were also installed.
This video shows the work done by the group at the University of Wisconsin, Madison on the camera for the pSCT. The camera is five feet across and weighs several hundred pounds. It currently features an array of 1600 pixels based on silicon photomultiplier sensors and custom electronics to capture Cherenkov light flashes focused by the dual-mirror pSCT optics. The camera is sensitive to individual photons with nanosecond timing resolution. This video explains the integration and testing of the camera, including the first recording of a light flash by the integrated camera. Video Produced by Craig Wild (University of Wisconsin Communications).