Production and installation of first GEM station in CMS

In 2017 and during the whole 2018 LHC has reached the record beam luminosity $2 \cdot 10^{34}$ cm$^{-2}$ s$^{-1}$, around a factor of two beyond the LHC design. In December 2018 the Large Hadron Collider (LHC) entered the LS2 phase (Long Shutdown 2), which will last until the beginning of 2021, in which the maintenance program of LHC and the other smaller accelerators is scheduled. To cope with this and also looking at the following LHC phase in which the luminosity will be increased to $5 \cdot 10^{34}$ cm$^{-2}$ s$^{-1}$ the LHC experiments must be upgraded as well. In this context the muon subsystem of the CMS experiment began installing the first GEM based detectors station (GE1/1) in July 2019, almost 5 meters from the point of interaction. GE1/1 will consist of 144 triple Gas Electron Multiplier (GEM) detectors, which will work together with the Cathode Strip Chamber (CSC) station ME1/1, improving tracking and triggering of muons produced in the pseudorapidity in range $1.6 < \vert\eta\vert < 2.15.$ The installation in CMS is now underway at a good pace. The first 72 chambers have been installed together with their services (gas, cooling, low voltage and high voltage etc.) while the completion of the station is foreseen in spring 2020. This contribution will summarize the detector design along with the steps a detector must pass before being approved for the installation in CMS. The status of the operations will be presented, together with the tools developed to monitor the detector parameters during installation. Finally the plans for the installation and commissioning of the entire project will be outlined.