The fifth Sloan Digital Sky Survey Local Volume Mapper (LVM) is a wide-field integral field unit survey that uses an array of four 160 mm fixed telescopes with siderostats to minimize the number of moving parts. An individual telescope observes the science or calibration field independently and is synchronized with the science exposure. We developed the LVM Acquisition and Guiding Package (LVMAGP)-optimized telescope control software program for LVM observations, which can simultaneously control four focusers, three K-mirrors, one fiber selector, four mounts (siderostats), and seven guide cameras. This software is built on a hierarchical architecture and the SDSS framework and provides three key sequences: autofocus, field acquisition, and autoguide. We designed and fabricated a proto-model siderostat to test the telescope pointing model and LVMAGP software. The mirrors of the proto-model were designed as an isogrid open-back type, which reduced the weight by 46% and enabled reaching thermal equilibrium quickly. In addition, deflection due to bolting torque, self-gravity, and thermal deformation was simulated, and the maximum scatter of the pointing model induced by the tilt of optomechanics was predicted to be 4′.4, which can be compensated for by the field acquisition sequence. We performed a real sky test of LVMAGP with the proto-model siderostat and obtained field acquisition and autoguide accuracies of 0″.38 and 1″.5, respectively. It met all requirements except for the autoguide specification, which will be resolved by more precise alignment among the hardware components at Las Campanas Observatory.
A mode matching telescope for an EPR squeezer was designed with confocal off-axis configuration. Coupling loss is calculated as 0.02%, and the fabrication is expected to be feasible based on sensitivity analysis and Monte-Carlo simulation.
Sloan Digital Sky Survey fifth-generation (SDSS-V) Local Volume Mapper (LVM) is a wide-field IFU survey that uses an array of four 160 mm telescopes. It provides IFU spectra over the optical range with R ∼ 4,000 to reveal the inner components of galaxies and the evolution of the universe. Each telescope observes the science field or the calibration field independently, but all of them should be simultaneously synchronized with the science exposure. To minimize the moving parts, the LVM adopted the siderostat design with a field derotator. We designed the optimized control software for our LVM observation, lvmagp, which controls four focusers, three K-mirror derotators, one fiber selector, four mounts (siderostats), and seven guide cameras. It was built on its owen user interface and messaging protocol called actor and clu based on asynchronous programming. The lvmagp provides three key sequences: autofocus sequence, field acquisition sequence, and autoguide sequence. Also, we designed and fabricated the proto-model siderostat for the software test. The real sky test was made with proto-model siderostat, and the lvmagp showed arcsecond-level field acquisition and autoguide accuracy.
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