R. Cirami

ESPRESSO: the Echelle spectrograph for rocky exoplanets and stable spectroscopic observations

ESPRESSO, the Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations, will combine the efficiency of modern echelle spectrograph design with extreme radial-velocity precision. It will be installed on ESOs VLT in order to achieve a gain of two magnitudes with respect to its predecessor HARPS, and the instrumental radialvelocity precision will be improved to reach cm/s level. Thanks to its characteristics and the ability of combining incoherently the light of 4 large telescopes, ESPRESSO will offer new possibilities in various fields of astronomy. The main scientific objectives will be the search and characterization of rocky exoplanets in the habitable zone of quiet, nearby G to M-dwarfs, and the analysis of the variability of fundamental physical constants. We will present the ambitious scientific objectives, the capabilities of ESPRESSO, and the technical solutions of this challenging project.

The ALMA common software: a developer-friendly CORBA-based framework

The ALMA Common Software (ACS) is a set of application frameworks built on top of CORBA. It provides a common software infrastructure to all partners in the ALMA collaboration. The usage of ACS extends from high-level applications such as the Observation Preparation Tool [7] that will run on the desk of astronomers, down to the Control Software [6] domain. The purpose of ACS is twofold: from a system perspective, it provides the implementation of a coherent set of design patterns and services that will make the whole ALMA software [1] uniform and maintainable; from the perspective of an ALMA developer, it provides a friendly programming environment in which the complexity of the CORBA middleware and other libraries is hidden and coding is drastically reduced. The evolution of ACS is driven by a long term development plan, however on the 6-months release cycle the plan is adjusted based on incoming requests from ALMA subsystem development teams. ACS was presented at SPIE 2002[2]. In the two years since then, the core services provided by ACS have been extended, while the coverage of the application framework has been increased to satisfy the needs of high-level and data flow applications. ACS is available under the LGPL public license. The patterns implemented and the services provided can be of use also outside the astronomical community; several projects have already shown their interest in ACS. This paper presents the status of ACS and the progress over the last two years. Emphasis is placed on showing how requests from ACS users have driven the selection of new features.

Application development using the ALMA common software

The ALMA Common Software (ACS) provides the software infrastructure used by ALMA and by several other telescope projects, thanks also to the choice of adopting the LGPL public license. ACS is a set of application frameworks providing the basic services needed for object oriented distributed computing. Among these are transparent remote object invocation, object deployment and location based on a container/component model, distributed error, alarm handling, logging and events. ACS is based on CORBA and built on top of free CORBA implementations. Free software is extensively used wherever possible. The general architecture of ACS was presented at SPIE 2002. ACS has been under development for 6 years and it is midway through its development life. Many applications have been written using ACS; the ALMA test facility, APEX and other telescopes are running systems based on ACS. This is therefore a good time to look back and see what have been until now the strong and the weak points of ACS in terms of architecture and implementation. In this perspective, it is very important to analyze the applications based on ACS, the feedback received by the users and the impact that this feedback has had on the development of ACS itself, by favoring the development of some features with respect to others. The purpose of this paper is to describe the results of this analysis and discuss what we would like to do in order to extend and improve ACS in the coming years, in particular to make application development easier and more efficient.

Adoption of new software and hardware solutions at the VLT: the ESPRESSO control architecture case

ESPRESSO is a fiber-fed cross-dispersed echelle spectrograph which can be operated with one or up to 4 UT (Unit Telescope) of ESOs Very Large Telescope (VLT). It will be located in the Combined-Coudé Laboratory (CCL) of the VLT and it will be the first permanent instrument using a 16-m equivalent telescope. The ESPRESSO control software and electronics are in charge of the control of all instrument subsystems: the four Coudé Trains (one for each UT), the front-end and the fiber-fed spectrograph itself contained within a vacuum vessel. The spectrograph is installed inside a series of thermal enclosures following an onion-shell principle with increasing temperature stability from outside to inside. The proposed electronics architecture will use the OPC Unified Architecture (OPC UA) as a standard layer to communicate with PLCs (Programmable Logical Controller), replacing the old Instrument Local Control Units (LCUs) for ESO instruments based on VME technology. The instrument control software will be based on the VLT Control Software package and will use the IC0 Field Bus extension for the control of the instrument hardware. In this paper we present the ESPRESSO software architectural design proposed at the Preliminary Design Review as well as the control electronics architecture.

BATMAN: a DMD-based multi-object spectrograph on Galileo telescope

Next-generation infrared astronomical instrumentation for ground-based and space telescopes could be based on MOEMS programmable slit masks for multi-object spectroscopy (MOS). This astronomical technique is used extensively to investigate the formation and evolution of galaxies. We are developing a 2048x1080 Digital-Micromirror-Device-based (DMD) MOS instrument to be mounted on the Galileo telescope and called BATMAN. A two-arm instrument has been designed for providing in parallel imaging and spectroscopic capabilities. The field of view (FOV) is 6.8 arcmin x 3.6 arcmin with a plate scale of 0.2 arcsec per micromirror. The wavelength range is in the visible and the spectral resolution is R=560 for 1 arcsec object (typical slit size). The two arms will have 2k x 4k CCD detectors. ROBIN, a BATMAN demonstrator, has been designed, realized and integrated. It permits to determine the instrument integration procedure, including optics and mechanics integration, alignment procedure and optical quality. First images and spectra have been obtained and measured: typical spot diameters are within 1.5 detector pixels, and spectra generated by one micro-mirror slits are displayed with this optical quality over the whole visible wavelength range. Observation strategies are studied and demonstrated for the scientific optimization strategy over the whole FOV. BATMAN on the sky is of prime importance for characterizing the actual performance of this new family of MOS instruments, as well as investigating the operational procedures on astronomical objects. This instrument will be placed on the Telescopio Nazionale Galileo mid-2015.

Challenges and peculiarities of ESPRESSO Data Flow Cycle: from target choice to scientific results

Since the beginning of the ESPRESSO (Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations) project, it has been recognized that the expected challenging scientific results can be achieved only if an integrated view of the end-to-end operations is properly tackled. Hunting for rocky exoplanets and/or studying the possible variations of physical constants requires not only a dedicated, state-of-the-art spectrograph in terms of hardware and optics, but also a tailored observation strategy, data reduction pipeline and data analysis tools (ESPRESSO will be the first ESO instrument for which a customized Data Analysis Software will be provided to the community by the Consortium). In this paper we present the planned data flow system (DFS) for ESPRESSO as emerged after the Preliminary Design Review held in November 2011. Main requirements in terms of observation strategy/preparation and data reduction/analysis are analyzed and the corresponding foreseen (conceptual) design, able to fulfill them, discussed. Eventually, peculiarities and challenges needed to adapt ESPRESSO DFS in the pre-existing ESO/VLT DFS framework are outlined.

EVALSO: enabling virtual access to Latin American southern observatories

In the field of observational astrophysics, the remoteness of the facilities and the ever increasing data volumes and detectors poses new technological challenges. As an example, the VISTA and VST wide field telescopes, which are being constructed at the ESOs Cerro Paranal Observatory and will be ready in the next few years, have cameras which will produce after just one year of operation a volume of data that will exceed all the data collected by the VLT since the start of operations in 1999. This sets serious limitations if such large quantities of data must be transferred and accessed in a short time by the participating European Institutions. The EVALSO project, approved by the European Community, addresses these targets in two major ways. It will create a physical infrastructure to efficiently connect these facilities to Europe. This infrastructure will be complementary to the international infrastructure already created in the last years with the EC support (RedCLARA, ALICE, GEANT). Besides this, it will provide the astronomers with Virtual Presence (VP), i.e. the tools to perform and control an astronomical observation from the users site. The main role of INAF - Astronomical Observatory of Trieste (OAT) within the project will be the definition of the architecture, the development of VP system and the integration of a prototype to be used as a demonstrator. This paper will focus on the description of the Virtual Presence system.

Conceptual design of the control software for the European Solar Telescope

Aim of this paper is to present an overview of the conceptual design of the Control Software for the European Solar Telescope (EST), as emerged after the successful Conceptual Design Review held in June 2011 which formally concluded the EST Preliminary Design Study. After a general description of ECS (EST Control Software) architecture end-to-end, from operation concepts and observation preparations to the control of the planned focal plane instruments, the paper focuses on the arrangement devised to date of ECS to cope with the foreseen scientific requirements. EST major subsystems together with the functions to be controlled are eventually detailed and discussed.

Control software and electronics architecture design in the framework of the E-ELT instrumentation

During the last years the European Southern Observatory (ESO), in collaboration with other European astronomical institutes, has started several feasibility studies for the E-ELT (European-Extremely Large Telescope) instrumentation and post-focal adaptive optics. The goal is to create a flexible suite of instruments to deal with the wide variety of scientific questions astronomers would like to see solved in the coming decades. In this framework INAF-Astronomical Observatory of Trieste (INAF-AOTs) is currently responsible of carrying out the analysis and the preliminary study of the architecture of the electronics and control software of three instruments: CODEX (control software and electronics) and OPTIMOS-EVE/OPTIMOS-DIORAMAS (control software). To cope with the increased complexity and new requirements for stability, precision, real-time latency and communications among sub-systems imposed by these instruments, new solutions have been investigated by our group. In this paper we present the proposed software and electronics architecture based on a distributed common framework centered on the Component/Container model that uses OPC Unified Architecture as a standard layer to communicate with COTS components of three different vendors. We describe three working prototypes that have been set-up in our laboratory and discuss their performances, integration complexity and ease of deployment.

Bulk data transfer distributer: a high performance multicast model in ALMA ACS

A high performance multicast model for the bulk data transfer mechanism in the ALMA (Atacama Large Millimeter Array) Common Software (ACS) is presented. The ALMA astronomical interferometer will consist of at least 50 12-m antennas operating at millimeter wavelength. The whole software infrastructure for ALMA is based on ACS, which is a set of application frameworks built on top of CORBA. To cope with the very strong requirements for the amount of data that needs to be transported by the software communication channels of the ALMA subsystems (a typical output data rate expected from the Correlator is of the order of 64 MB per second) and with the potential CORBA bottleneck due to parameter marshalling/de-marshalling, usage of IIOP protocol, etc., a transfer mechanism based on the ACE/TAO CORBA Audio/Video (A/V) Streaming Service has been developed. The ACS Bulk Data Transfer architecture bypasses the CORBA protocol with an out-of-bound connection for the data streams (transmitting data directly in TCP or UDP format), using at the same time CORBA for handshaking and leveraging the benefits of ACS middleware. Such a mechanism has proven to be capable of high performances, of the order of 800 Mbits per second on a 1Gbit Ethernet network. Besides a point-to-point communication model, the ACS Bulk Data Transfer provides a multicast model. Since the TCP protocol does not support multicasting and all the data must be correctly delivered to all ALMA subsystems, a distributer mechanism has been developed. This paper focuses on the ACS Bulk Data Distributer, which mimics a multicast behaviour managing data dispatching to all receivers willing to get data from the same sender.