Achieving smooth and efficient slew movements on telescope mounts is crucial for minimizing structural stress, reaching maximum velocities, and ensuring efficient operation. Traditional slew trajectory generation methods often fall short in optimizing trajectories for time, resulting in unnecessarily long slew times that reduce telescope efficiency and potentially affect observation opportunities. Additionally, traditional methods often fail to converge smoothly to tracking velocities, leading to abrupt changes in motion that can compromise settling time. This paper presents a novel time-optimal jerk-limited trajectory generator algorithm for slew movements and its current implementation at the SOAR telescope as part of the Mount Control Upgrade Project. This algorithm effectively addresses these limitations by simultaneously optimizing for user-defined constraints on position, velocity, acceleration, and jerk while achieving minimum time. The algorithm produces a jerk-constrained trajectory that converges to a constant velocity reference specified by position, velocity, and time (PVT) commands, ensuring smooth and efficient convergence to tracking velocities while minimizing structural stress and settling time. The proposed algorithm is simple to implement and can be used to generate smooth slew trajectories in telescopes and actuators in general.
This paper presents an approach to investigate the correlation between the long-term variability of photometric zero-point curves and the quality of the primary mirror coatings in 4-m class telescopes, specifically focusing on Blanco (Cerro Tololo, Chile) and SOAR (Cerro Pachón, Chile), both NOIRLab facilities. Using imaging data acquired with DECam (Blanco) and Goodman High-Throughout Spectrograph (SOAR), we are constructing an extensive dataset comprising observational data taken at similar instrumental conditions, sampling a substantially long period of the telescopes' operations. The analysis involves a comprehensive comparison of the photometric zero-point light curves against the reflectivity curve of the primary mirror of each telescope, taken after each cleaning cycle. This study aims to aid in optimizing maintenance efforts, including scheduling cleaning procedures and re-aluminizing tasks, thereby enhancing the operational efficiency and longevity of the telescopes.
The SOAR telescope was designed to have a bare Aluminum coating. This coating is performed in the Gemini-South sputtering facility. Two coatings have been done on the SOAR mirror (2004 and 2009). On both occasions, the reflectivity obtained for the UV-blue were lower than the reflectivity of the nominal bare Aluminum. Various tests have been done during 2018 and 2019, in order to reach a higher reflectivity in the UV, including changes in the coating recipe. We report here the progress to date, the performance that we have reached and the problems we have faced in this 8-meter coating facility.
KEYWORDS: Telescopes, Control systems, Sensors, Amplifiers, Field programmable gate arrays, Computer programming, Data acquisition, Observatories, Control systems design
The Southern Astrophysical Research (SOAR) Telescope is a 4.1 meter aperture telescope situated in Cerro Pachon, IV Region, Chile. The telescope works from the atmospheric cut-off in the blue (320 nm) to the near infrared and has been designed to deliver the highest possible angular resolution at optical wavelengths. The telescope has an altazimuth mount which is controlled by the Mount Control Unit (MCU) system.
The SOAR Mount Control Unit Upgrade Project seeks to replace the current MCU in the SOAR telescope. The new control unit will be based on the National Instruments cRIO-9039 controller, which will allow to improve the telemetry, improve fault detection and use new digital control techniques.
This will allow a more compact and robust MCU. This paper introduces the project, shows the control architecture and the current status of the new MCU implementation.
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