The operations at the Paranal Observatory have hit their 25th year milestone for the Unit Telescope 1 that saw first light in 1998. We will review different technical and organizational aspects of the technical operations over the last years. First, we present an update on the reliability and availability of the observatory systems and in particular the scientific instruments over the last decade. Corrective maintenance metrics will be presented to show the trends and compare with previous similar studies. Second, we present a review of our current maintenance processes after an analysis started recently for planning the future integrated operations with the Extremely Large telescope (ELT). The exercise revealed how the resources are used as well as the gaps and potential for improvements, in particular in the context of our methodology of Maintenance in Conditions of Operation (MCO), which we implemented in 2014. Finally, we will give an update on obsolescence management by describing some of the solutions we have implemented, and our strategy and forecast for the future decades given the aging of the Observatory and the need to keep the Very Large Telescope (VLT) competitive in the era of ELT.
The advancement of technologies in Interferometry and Adaptive Optics (AO) at the Very Large Telescope (VLT) at Paranal Observatory calls for an updated approach to maintenance strategies. This new approach draws on the observatory's rich operational experience. The Integrated Operations Program (IOP), aiming at integrating operations of VLT and ELT, supports this strategic change, encouraging the ongoing enhancement of maintenance practices. This paper outlines the learnings from recent maintenance work following the installation of Interferometry systems and the Adaptive Optics Facility (AOF). It describes the new maintenance framework being put into practice through the IOP for the Extremely Large Telescope (ELT) and its instruments, breaking it down into categories of Improvement, Preventive, Corrective, and Operational Maintenance types. It also covers root cause analyses for a contamination event. The main goal of this document is to highlight the most significant maintenance challenges faced by the Instrumentation Group at Paranal Observatory, focusing on the period when AOF was set up and the latest interferometry instruments were introduced. Maintenance processes are examined through several observational periods, starting with period 103, which corresponds to the year 2019. The paper also introduces the Technical Time Request system, a tool used for planning the time needed for maintenance activities within the overall schedule of the observatory, which includes all tasks, both technical and observational.
SPHERE is the VLT exo-planet imager and is based on XAO and coronagraphy. Malfunctioning DM actuators can have a severe impact on the instrument contrast. 18 dead and 8 sluggish actuators were identified during commissioning, but the actuator's behavior needs to be monitored during the whole instrument lifetime. Daily, the temporal responses of SPHERE's 1377 actuators are measured at 1380Hz. The method to automatically identify the status of the actuators is based on machine learning. We used the SciKit toolbox (INRIA, France) and implemented a Support Vector Machine algorithm. The model was trained on data acquired on 167 daily measurements of dead actuators, 73 daily measurements of sluggish actuators and 334 daily measurements of good actuators. The model was then validated on 73 daily measurements of dead actuators, 26 daily measurements of sluggish actuators and 147 daily measurements of good actuators.
The method accurately identified malfunctioning actuators with an extremely low number of false positives (1). The method is easy to implement, fast (30ms) and easily scalable to systems with more degrees of liberty such as MOEMS DMs and the future ELT DMs.
In early 2020 the upgraded1 CRIRES2 instrument, was installed at the VLT, however the onset of the global pandemic prevented the completion of some aspects of the installation while characterisation and commissioning had to be conducted with a remote connection from Europe. This resulted in a somewhat experimental, ad-hoc, approach to characterisation that required tight co-ordination between Paranal scientists and the instrument team in Europe. Moreover, with the observatory operating at minimal staffing, we had to find workarounds for some unfinished parts of the installation and adapt our characterisation, calibration and operations strategies accordingly. In particular, we discuss the adaptation made to the metrology strategy that illustrates well the pragmatic and ultimately successful approach adopted for getting CRIRES+ ready for operations.
CRIRES+ extended the capabilities of CRIRES, the CRyogenic InfraRed Echelle Spectrograph. It transformed this VLT instrument into a cross-dispersed spectrograph to increase the wavelength range that is covered simultaneously by a factor of ten. In addition, a new detector focal plane array of three Hawaii 2RG detectors with a 5.3 μm cut-off wavelength replaced the existing detectors. Amongst many other improvements a new spectropolarimetric unit was added and the calibration system has been enhanced. The instrument was installed at the VLT on Unit Telescope 3 beginning of 2020 and successfully commissioned and verified for science operations during 2021, partly remote from Europe due to the pandemic. The instrument was subsequently offered to the community from October 2021 onwards. This article describes the performance and capabilities of this development and presents on sky results.
The ESO’s adaptive optics facility (AOF) is ending its commissioning at Paranal (Chile). It feeds two second-generation instruments of the VLT-UT4 telescope, HAWK-I and MUSE, with turbulence corrected wavefronts through the GALACSI and GRAAL modules. The main features of the AOF are its deformable secondary mirror with 1170 actuators and a laser asterism of 4 artificial stars that probe the atmosphere via four high-resolution Shack-Hartmann wavefront sensors (WFS), each with 40x40 subapertures. The system provides ground layer adaptive optics (GLAO) and laser tomography adaptive optics (LTAO) capabilities. In order to support the commissioning phases of the project, and later optimize and diagnose the operation of the system, a turbulence profiler has been developed and installed in SPARTA, the AOF real time controller (RTC). The profiler estimates two key turbulence parameters: the Cn2(h) and the outer scale (L0(h)) profiles and no limit on the number of the estimated layers exists, but for eight layers, the method takes about 2 minutes to yield a full characterization of the atmosphere. The maximum line of sight distance that the profiler can probed the atmosphere depends on the star separation defined for each operation mode: 3km for GRAAL; 14 km for GALACSI wide field and over 35km for GALACS narrow field mode. The remaining turbulence above these maxima (unseen turbulence from the undetected layers) are essential in the GRAAL mode and it is reliably estimated thanks to a novel method to determine the noise in the WFSs, which is mandatory for estimating this upper segment of the turbulence. The technique is also useful to alert about operational problems such as dome seeing and mis-registrations. The method is currently installed in the SPARTA RTC, providing continuous online estimations for the GALACSI (narrow and wide field modes), and for GRAAL mode. Results for several nights comprising hundreds of profiles show very good agreement with other independent measurements.
After 20 years of operations, the Paranal Observatory has accumulated some experience with maintenance of systems, and has lately adopted the methodology called ‘Maintien en Condition Operationnelle’ (MCO). We will describe and review the practical implementation of this strategy, the tools used, the benefits and challenges as well as practical examples and how it is overall managed. The approach is also a benchmarking exercise for operation of the ESO-ELT in the future.
Paranal Observatory has a set of astroclimate monitoring instruments; such as DIMM, MASS-DIMM and SLODAR which are delivering information about the sky quality in terms of; seeing, coherence time, high altitude wind speed (200mb) and Cn2 profiles to support the observations. SPHERE instrument is an Extreme Adaptive Optics that uses a Shack-Hartmann wavefront sensor running at close loop frequency of 1.3KHz. The instrument saves close loop snapshot every minute and from the data saved the system retrieves the r0 and the cross wind speed. The wind speed is calculated using a cross-corrrelation based on the peak identification. The knowledge of t his parameter is essential to understand the performances of the AO system, and to optimize its control laws every minutes. The data from the astroclimatic system monitor will help to correlate the turbulence events with the transverse wind speed retrieved from SPHERE close loop data. The goal of this work is also to compare the different atmospheric monitors with the effective turbulence estimation from the focal plane itself (Differential Tip-Tilt Sensor).
The High Acuity Wide field K-band Imager (HAWK-I) instrument is a cryogenic wide field imager operating in the wavelength range 0.9 to 2.5 microns. It has been in operations since 2007 on the UT4 at the Very Large Telescope Observatory in seeing-limited mode. In 2017-2018, GRound Layer Adaptive optics Assisted by Lasers module (GRAAL) will be in operation and the system GRAAL+HAWK-I will be commissioned. It will allow: deeper exposures for nearly point-source objects, or shorter exposure times for reaching the same magnitude, and/or deeper detection limiting magnitude. With GRAAL, HAWK-I will operate more than 80% of the time with an equivalent K-band seeing of 0.55" (instead of 0.7" without GRAAL). GRAAL is already installed and the operations without adaptive optics were commissioned in 2015. We discuss here the latest updates on performance from HAWK-I without Adaptive Optics (AO) and the preparation for the commissioning of the system GRAAL+HAWK-I.
GRAAL is the adaptive optics module feeding the wide-field IR imager HAWK-I at the VLT observatory. As part of the adaptive optics facility, GRAAL is equipped with 4 Laser-guide star wave-front sensors and provides a large field-of-view, ground layer correction system to HAWK-I. After a successful testing in Europe, the module has been re-assembled in Chile and installed at the Nasmyth-A platform of Yepun, the fourth Unit telescope of the observatory. We report on the installation of GRAAL on the mountain and on its first testing in stand-alone and on-sky.
For two years starting in February 2014, the AO modules GRAAL for HAWK-I and GALACSI for MUSE of the Adaptive Optics Facility project have undergone System Testing at ESO's Headquarters. They offer four different modes: NGS SCAO, LGS GLAO in the IR, LGS GLAO and LTAO in the visible. A detailed characterization of those modes was made possible by the existence of ASSIST, a test bench emulating an adaptive VLT including the Deformable Secondary Mirror, a star simulator and turbulence generator and a VLT focal plane re-imager. This phase aimed at validating all the possible components and loops of the AO modules before installation at the actual VLT that comprises the added complexity of real LGSs, a harsher non-reproducible environment and the adaptive telescope control.
In this paper we present some of the major results obtained and challenges encountered during the phase of System Tests, like the preparation of the Acquisition sequence, the testing of the Jitter loop, the performance optimization in GLAO and the offload of low-order modes from the DSM to the telescope (restricted to the M2 hexapod). The System Tests concluded with the successful acceptance, shipping, installation and first commissioning of GRAAL in 2015 as well as the acceptance and shipping of GALACSI, ready for installation and commissioning early 2017.
KEYWORDS: Observatories, Calibration, Iterated function systems, Optical spheres, Sensors, Optical filtering, Stars, Polarimetry, Control systems, K band
The Paranal Very Large Telescopes (VLT) Observatory is a complex multifunctional observatory where many different systems are generating telemetry parameters.As systems becoming more and more complex, also the amount of telemetry data is increasing. This telemetry data is usually saved in various data repositories.In order to obtain a full system overview, it is necessary to link all that data in a meaningful and easy to interpret way. A step forward from simple telemetry data visualisation has been done by developing a new tool that can combine different data sources and has a powerful graphing capability.This new tool, called SystMon, is developed in iPython an interactive-web browser environment under the philosophy of notebooks which combine the code and the final product. The application can be shared among other colleagues and having the code side by side gives the accessibility to inspect and review the process improving and adding new capabilities to the application. SystMon allows to manipulate, generate andvisualise data in different types of graphs and also to create directly statistical reports. SystMon helps the user tomodel, visualiseand interpret telemetry data in a web-based platform for monitoring the health of systems, understanding short- and long-term behaviour and to anticipate corrective interventions.
Two algorithms were recently studied for C2n profiling from wide-field Adaptive Optics (AO) measurements on GeMS (Gemini Multi-Conjugate AO system). They both rely on the Slope Detection and Ranging (SLODAR) approach, using spatial covariances of the measurements issued from various wavefront sensors. The first algorithm estimates the C2n profile by applying the truncated least-squares inverse of a matrix modeling the response of slopes covariances to various turbulent layer heights. In the second method, the profile is estimated by deconvolution of these spatial cross-covariances of slopes. We compare these methods in the new configuration of ESO Adaptive Optics Facility (AOF), a high-order multiple laser system under integration. For this, we use measurements simulated by the AO cluster of ESO. The impact of the measurement noise and of the outer scale of the atmospheric turbulence is analyzed. The important influence of the outer scale on the results leads to the development of a new step for outer scale fitting included in each algorithm. This increases the reliability and robustness of the turbulence strength and profile estimations.
The high multiplex advantage of VIMOS, the VLT visible imager and multi-object/integral-field spectrometer, makes it
a powerful instrument for large-scale spectroscopic surveys of faint sources. Following community input and
recommendations by ESO's Science and Technology Committee, in 2009 it was decided to upgrade the instrument. This
included installing an active flexure compensation system and replacing the detectors with CCDs that have a far better
red sensitivity and less fringing. Significant changes have also been made to the hardware, maintenance and operational
procedures of the instrument with the aim of improving availability and productivity. Improvements have also been
made to the data reduction pipeline. The upgrade will end in 2012 and the results of the program will be presented here.
Gordon Gillet, José Luis Alvarez, Juan Beltrán, Pierre Bourget, Roberto Castillo, Álvaro Diaz, Nicolás Haddad, Alfredo Leiva, Pedro Mardones, Jared O'Neal, Mauricio Ribes, Miguel Riquelme, Pascal Robert, Chester Rojas, Javier Valenzuela
This presentation provides interesting miscellaneous information regarding the instrumentation activities at Paranal
Observatory. It introduces the suite of 23 instruments and auxiliary systems that are under the responsibility of the
Paranal Instrumentation group, information on the type of instruments, their usage and downtime statistics. The data is
based on comprehensive data recorded in the Paranal Night Log System and the Paranal Problem Reporting System
whose principles are explained as well. The work organization of the 15 team members around the high number of
instruments is laid out, which includes:
- Maintaining older instruments with obsolete components
- Receiving new instruments and supporting their integration and commissioning
- Contributing to future instruments in their developing phase.
The assignments of the Instrumentation staff to the actual instruments as well as auxiliary equipment (Laser Guide Star
Facility, Mask Manufacturing Unit, Cloud Observation Tool) are explained with respect to responsibility and scheduling
issues. The essential activities regarding hardware & software are presented, as well as the technical and organizational
developments within the group towards its present and future challenges.
REMIR is the NIR camera of the automatic REM (Rapid Eye Mount) Telescope located at ESO-La Silla Observatory (Chile) and dedicated to monitor the afterglow of Gamma Ray Burst events. During the last two years, the REMIR camera went through a series of cryogenics problems, due to the bad functioning of the Leybold cryocooler Polar SC7. Since we were unable to reach with Leybold for a diagnosis and a solution for such failures, we were forced to change drastically the cryogenics of REMIR, going from cryocooler to LN2: we adopted an ad-hoc modified Continuous Flow Cryostat, a cryogenics system developed by ESO and extensively used in ESO instrumentation, which main characteristic is that the LN2 vessel is separated from the cryostat, allowing a greater LN2 tank, then really improving the hold time. In this paper we report the details and results of this operation.
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