Stefano Zampieri

SPARTA for the VLT: status and plans

SPARTATM, the ESO Standard Platform for Adaptive optics Real Time Applications, is the real time computing platform serving 3 major 2nd generation instruments at the VLT (SPHERE, GALACSI and GRAAL) with plans to serve more, smaller, instruments in the near future. SPARTA offers a very modular and fine-grained architecture which is generic enough to serve a variety of AO systems. SPARTA includes the definitions of all the interfaces between those modules and provides libraries and tools to implement and test the various modules as well as a map to technologies capable of delivering the required performance, most of them innovative with respect to ESO standards in use. For the above mentioned instruments, SPARTA provides also a complete implementation of the AO application, with features customized for each of the 3 instruments. In this paper we present the architecture of SPARTA, its technologies, functions, performance and test tools as well as the plans to increase the reach of the platform to smaller system with what we call SPARTA Light.

From Chile to Europe in minutes: handling the data stream from ESO's Paranal Observatory

The ESO telescopes in Chile are operated in a geographically distributed scheme, in which some of the essential steps in the end-to-end observing chain take place in Europe. Most notably, the health status of the instruments as derived from the data themselves is monitored in Europe and the results fed back to the observatory within the hour. The flexibility of this scheme strongly depends on the speed with which the data stream produced by the telescopes can be sent to Europe for analysis and storage. The main challenge to achieve a fast intercontinental data transfer is the data volume itself, which currently reaches an average 25 GB/night (compressed) for the four VLT Unit Telescopes. Since late 2008, this stream has been entirely transferred through the internet via a 4.56 Mbit/s bandwidth assured via a Quality of Service policy, which sufficed to transfer an average night of data within a few hours. A very recent enlargement of this capacity to 9.12 Mbit/s will soon allow the addition of the calibration data for VISTA, the new infrared survey telescope on Paranal, to the data stream transferred through the internet. Ultimately, the average data volume produced on Paranal once the visible VLT Survey Telescope (VST) and the full complement of second-generation VLT instruments becomes available is expected to exceed 200 GB/night. Transferring it over the internet will require a new fiber-based infrastructure currently under construction, as well as the use of additional high bandwidth channels. This infrastructure, provided by the European Union co-funded project EVALSO, should provide a data transfer capacity exceeding 1 Gbit/s that will allow the transfer to Europe of the entire Paranal data stream, as well as that of the nearby Observatory of Cerro Armazones and of the future European Extremely Large Telescope, with a delay of minutes at most since the data were taken.

VLT Interferometer Data Flow System: from observation preparation to data processing

In this article we present the Data Flow System (DFS) for the Very Large Telescope Interferometer (VLTI). The Data Flow System is the VLT end-to-end software system for handling astronomical observations from the initial observation proposal phase through the acquisition, processing and control of the astronomical data. The Data Flow system is now in the process of installation and adaptation for the VLT Interferometer. The DFS was first installed for VLTI first fringes utilising the siderostats together with the VINCI instrument and is constantly being upgraded in phase with the VLTI commissioning. When completed the VLT Interferometer will make it possible to coherently combine up to three beams coming from the four VLT 8.2m telescopes as well as from a set of initially three 1.8m Auxiliary Telescopes, using a Delay Line tunnel and four interferometry instruments. Observations of objects with some scientific interest are already being carried out in the framework of the VLTI commissioning using siderostats and the VLT Unit Telescopes, making it possible to test tools under realistic conditions. These tools comprise observation preparation, pipeline processing and further analysis systems. Work is in progress for the commissioning of other VLTI science instruments such as MIDI and AMBER. These are planned for the second half of 2002 and first half of 2003 respectively. The DFS will be especially useful for service observing. This is expected to be an important mode of observation for the VLTI, which is required to cope with numerous observation constraints and the need for observations spread over extended periods of time.

Data flow system for the very large telescope interferometer

The Data Flow System is the VLT end-to-end system for handling astronomical observations from the initial observation proposal phase through the acquisition, processing and control of the astronomical data. The VLT Data Flow System has been in place since the opening of the first VLT Unit Telescope in 1998. When completed the VLT Interferometer will make it possible to coherently combine up to three beams coming from the four VLT 8.2m telescopes as well as from a set of initially three 1.8m Auxiliary Telescopes, using a Delay Line tunnel and four interferometry instruments. The Data Flow system is now in the process of installation and adaptation for the VLT Interferometer. Observation preparation for a multi-telescope system, handling large data volume of several tens of gigabytes per night are among the new challenges offered by this system. This introduction paper presents the VLTI Data Flow system installed during the initial phase of VLTI commissioning. Observation preparation, data archival, and data pipeline processing are addressed.

GALACSI integration and functional tests

GALACSI is the Adaptive Optics (AO) modules of the ESO Adaptive Optics Facility (AOF) that will correct the wavefront delivered to the MUSE Integral Field Spectrograph. It will sense with four 40×40 subapertures Shack-Hartmann wavefront sensors the AOF 4 Laser Guide Stars (LGS), acting on the 1170 voice-coils actuators of the Deformable Secondary Mirror (DSM). GALACSI has two operating modes: in Wide Field Mode (WFM), with the four LGS at 64” off axis, the collected energy in a 0.2”×0.2” pixel will be enhanced by a factor 2 at 750 nm over a Field of View (FoV) of 1’×1’ using the Ground Layer AO (GLAO) technique. The other mode, the Narrow Field Mode (NFM), provides an enhanced wavefront correction (Strehl Ratio (SR) of 5% (goal 10%) at 650 nm) but in a smaller FoV (7.5”×7.5”), using Laser Tomography AO (LTAO), with the 4 LGS located closer, at 10” off axis. Before being shipped to Paranal, GALACSI will be first integrated and fully tested in stand-alone, and then moved to a dedicated AOF facility to be tested with the DSM in Europe. At present the module is fully assembled, its main functionalities have been implemented and verified, and AO system tests with the DSM are starting. We present here the main system features and the results of the internal functional tests of GALACSI.

EVALSO, a high-bandwidth communication infrastructure to efficiently connect the ESO Paranal and the Cerro Armazones Observatories to Europe: demonstration activities and start of operations

EVALSO (Enabling Virtual Access to Latin-American Southern Observatories) is an international consortium of nine astronomical organizations, and research network operators, part-funded under the European Commission FP7, to create and exploit high-speed bandwidth connections to the observatories of Cerro Paranal and Cerro Armazones in Chile. The communication infrastructure was delivered in November 2010 and this paper reports on the initial results of the project and the demonstrations of its capabilities, including the possibilities that the new infrastructure opens up in the geographically distributed operation of the observatories.

The ESO science archive: supporting and enhancing science from the La Silla Paranal Observatory

The archive of the La Silla Paranal Observatory is a powerful science resource for the ESO astronomical community. It stores both the raw data generated by all ESO instruments and selected processed (science-ready) data. We present the new capabilities and user services that have recently been developed in order to enhance data discovery and usage in the face of the increasing volume and complexity of the archive holdings. Future plans to extend the new services to processed data from the Atacama Large Millimeter/submillimeter Array (ALMA) are also discussed.

Enhanced Data Discovery Services for the ESO Science Archive

The Messenger 172 – June 2018 the characteristics and limitations of each collection of processed data. This is particularly important, as it enables users to decide whether the data are suitable for their specific science goals. The systematic archive publication of such processed data dates back to 25 July 2011, with the first products produced by the Public Surveys conducted with the Visible and Infrared Survey Telescope for Astronomy (VISTA) infrared camera VIRCAM (Arnaboldi & Retzlaff, 2011). Processed data that were generated at ESO have been available since September 2013. An up-to-date overview of the released data is available online for contributed and pipeline processed data 2, 3.

ESO Phase 3 automatic data validation: groovy-based tool to assure the compliance of the reduced data with the Science Data Product Standard

The ESO Phase 3 infrastructure provides a channel to submit reduced data products for publication to the astronomical community and long-term data preservation in the ESO Science Archive Facility. To be integrated into Phase 3, data must comply to the ESO Science Data Product Standard regarding format (one unique standard data format is associated to each type of product, like image, spectrum, IFU cube, etc.) and required metadata. ESO has developed a Groovy based tool that carries out an automatic validation of the submitted reduced products that is triggered when data are uploaded and then submitted. Here we present how the tool is structured and which checks are implemented.

Adapting the VLT data flow system for handling high-data rates

The Data Flow System (DFS) for the ESO VLT provides a global approach to handle the flow of science related data in the VLT environment. It is a distributed system composed of a collection of components for preparation and scheduling of observations, archiving of data, pipeline data reduction and quality control. Although the first version of the system became operational in 1999 together with the first UT, additional developments were necessary to address new operational requirements originating from new and complex instruments which generate large amounts of data. This paper presents the hardware and software changes made to meet those challenges within the back-end infrastructure, including on-line and off-line archive facilities, parallel/distributed pipeline processing and improved association technologies.