Proc. SPIE. 10707, Software and Cyberinfrastructure for Astronomy V
KEYWORDS: Telescopes, Cameras, Calibration, Data acquisition, Data archive systems, Monte Carlo methods, Gamma radiation, Prototyping, Atmospheric Cherenkov telescopes, Device simulation, Data analysis
The Cherenkov Telescope Array (CTA) is a worldwide project aimed at building the next-generation groundbased gamma-ray observatory. CTA will be composed of two arrays of telescopes of different sizes, one each in the Northern and Southern hemispheres, to achieve full-sky coverage and a ten-fold improvement in sensitivity with respect to the present-generation facilities. Within the CTA project, the Italian National Institute for Astrophysics (INAF) is developing an end-to-end prototype of one of the CTA Small-Size Telescope’s designs with a dual-mirror (SST-2M) Schwarzschild-Couder optics design. The prototype, named ASTRI SST-2M, is located at the INAF “M.C. Fracastoro” observing station in Serra La Nave (Mt. Etna, Sicily) and has started its verification and performance validation phase in fall 2017. A mini-array of (at least) nine ASTRI telescopes has been proposed to be deployed at the CTA southern site, during the pre-production phase, by means of a collaborative effort carried out by institutes from Italy, Brazil, and South Africa. The CTA ASTRI team has developed a complete end-to-end software package for the reduction, up to the final scientific products, of raw data acquired with ASTRI telescopes with the aim of actively contributing to the global ongoing activities for the official data handling system of the CTA observatory. The group is also undertaking a massive production of Monte Carlo simulation data using the same software chain adopted by the CTA Consortium. Both activities are also carried out in the framework of the European H2020-ASTERICS (Astronomy ESFRI and Research Infrastructure Cluster) project. In this work, we present the main components of the ASTRI data reduction software package and report the status of its development. Preliminary results on the validation of both data reduction and telescope simulation chains achieved with real data taken by the prototype and simulations are also discussed.
Today the scientific community is facing an increasing complexity of the scientific projects, from both a technological and a management point of view. The reason for this is in the advance of science itself, where new experiments with unprecedented levels of accuracy, precision and coverage (time and spatial) are realised. Astronomy is one of the fields of the physical sciences where a strong interaction between the scientists, the instrument and software developers is necessary to achieve the goals of any Big Science Project. The Cherenkov Telescope Array (CTA) will be the largest ground-based very high-energy gamma-ray observatory of the next decades. To achieve the full potential of the CTA Observatory, the system must be put into place to enable users to operate the telescopes productively. The software will cover all stages of the CTA system, from the preparation of the observing proposals to the final data reduction, and must also fit into the overall system. Scientists, engineers, operators and others will use the system to operate the Observatory, hence they should be involved in the design process from the beginning. We have organised a workgroup and a workflow for the definition of the CTA Top Level Use Cases in the context of the Requirement Management activities of the CTA Observatory. Scientists, instrument and software developers are collaborating and sharing information to provide a common and general understanding of the Observatory from a functional point of view. Scientists that will use the CTA Observatory will provide mainly Science Driven Use Cases, whereas software engineers will subsequently provide more detailed Use Cases, comments and feedbacks. The main purposes are to define observing modes and strategies, and to provide a framework for the flow down of the Use Cases and requirements to check missing requirements and the already developed Use-Case models at CTA sub-system level. Use Cases will also provide the basis for the definition of the Acceptance Test Plan for the validation of the overall CTA system. In this contribution we present the organisation and the workflow of the Top Level Use Cases workgroup.
The ASTRI mini-array, composed of nine small-size dual mirror (SST-2M) telescopes, has been proposed to be installed at the southern site of the Cherenkov Telescope Array (CTA), as a set of preproduction units of the CTA observatory. The ASTRI mini-array is a collaborative and international eﬀort carried out by Italy, Brazil and South Africa and led by the Italian National Institute of Astrophysics, INAF. We present the main features of the current implementation of the Mini-Array Software System (MASS) now in use for the activities of the ASTRI SST-2M telescope prototype located at the INAF observing station on Mt. Etna, Italy and the characteristics that make it a prototype for the CTA control software system. CTA Data Management (CTADATA) and CTA Array Control and Data Acquisition (CTA-ACTL) requirements and guidelines as well as the ASTRI use cases were considered in the MASS design, most of its features are derived from the Atacama Large Millimeter/sub-millimeter Array Control software. The MASS will provide a set of tools to manage all onsite operations of the ASTRI mini-array in order to perform the observations speciﬁed in the short term schedule (including monitoring and controlling all the hardware components of each telescope and calibration device), to analyze the acquired data online and to store/retrieve all the data products to/from the onsite repository.
The increasing number of Very High Energy (VHE) sources discovered by the current generation of Cherenkov telescopes made particularly relevant the creation of a dedicated source catalogs as well as the cross-correlation of VHE and lower energy bands data in a multi-wavelength framework. The “TeGeV Catalog” hosted at the ASI Science Data Center (ASDC) is a catalog of VHE sources detected by ground-based Cherenkov detectors. The TeGeVcat collects all the relevant information publicly available about the observed GeV/TeV sources. The catalog contains also information about public light curves while the available spectral data are included in the ASDC SED Builder tool directly accessible from the TeGeV catalogue web page. In this contribution we will report a comprehensive description of the catalog and the related tools.
In the framework of the international Cherenkov Telescope Array (CTA) gamma-ray observatory, the Italian National Institute for Astrophysics (INAF) is developing a dual-mirror, small-sized, end-to-end prototype (ASTRI SST-2M), inaugurated on September 2014 at Mt. Etna (Italy), and a mini-array composed of nine ASTRI telescopes, proposed to be installed at the southern CTA site. The ASTRI mini-array is a collaborative effort led by INAF and carried out by institutes from Italy, Brazil, and South-Africa. The project is also including the full data handling chain from raw data up to final scientific products. To this end, a dedicated software for the online/ on-site/off-site data reconstruction and scientific analysis is under development for both the ASTRI SST-2M prototype and mini-array. The software is designed following a modular approach in which each single component and the entire pipeline are developed in compliance with the CTA requirements. Data reduction is conceived to be run on parallel computing architectures, as multi-core CPUs and graphic accelerators (GPUs), and new hardware architectures based on low-power consumption processors (e.g. ARM). The software components are coded in C++/Python/CUDA and wrapped by efficient pipelines written in Python. The final scientific products are then achieved by means of either science tools currently being used in the CTA Consortium (e.g. ctools) or specifically developed ones. In this contribution, we present the framework and the main software components of the ASTRI SST-2M prototype and mini-array data reconstruction and scientific analysis software package, and report the status of its development.
In the framework of the international Cherenkov Telescope Array (CTA) gamma-ray observatory, a mini-array of nine small-sized, dual-mirror (SST-2M) telescopes developed by the ASTRI Collaboration has been proposed to be installed at the future CTA southern site. In such a location, the capability of each telescope to process its own data before sending them to a central acquisition system provides a key advantage. We implemented the complete analysis chain required by a single telescope on a NVIDIA® Jetson™ TK1 development board, exceeding the nominal required real-time processing speed by more than a factor two, while staying within a very small power budget.
The ASTRI project of the Italian National Institute for Astrophysics (INAF) is developing, in the framework of the Cherenkov Telescope Array (CTA), an end-to-end prototype system based on a dual-mirror small-sized Cherenkov telescope. Data preservation and accessibility are guaranteed by means of the ASTRI Archive System (AAS) that is responsible for both the on-site and off-site archiving of all data produced by the different sub- systems of the so-called ASTRI SST-2M prototype. Science, calibration, and Monte Carlo data together with the dedicated Instrument Response Functions (IRFs) (and corresponding metadata) will be properly stored and organized in different branches of the archive. A dedicated technical data archive (TECH archive) will store the engineering and auxiliary data and will be organized under a parallel database system. Through the use of a physical system archive and a few logical user archives that reflect the different archive use-cases, the AAS has been designed to be independent from any specific data model and storage technology. A dedicated framework to access, browse and download the telescope data has been identified within the proposal handling utility that stores and arranges the information of the observational proposals. The development of the whole archive system follows the requirements of the CTA data archive and is currently carried out by the INAF-OAR & ASI-Science Data Center (ASDC) team. The AAS is fully adaptable and ready for the ASTRI mini-array that, formed of at least nine ASTRI SST-2M telescopes, is proposed to be installed at the CTA southern site.
The Large Observatory For x-ray Timing (LOFT) was studied within ESA M3 Cosmic Vision framework and participated in the final downselection for a launch slot in 2022-2024. Thanks to the unprecedented combination of effective area and spectral resolution of its main instrument, LOFT will study the behaviour of matter under extreme conditions, such as the strong gravitational field in the innermost regions of accretion flows close to black holes and neutron stars, and the supranuclear densities in the interior of neutron stars. The science payload is based on a Large Area Detector (LAD, 10 m<sup>2 </sup> effective area, 2-30 keV, 240 eV spectral resolution, 1° collimated field of view) and a Wide Field Monitor (WFM, 2-50 keV, 4 steradian field of view, 1 arcmin source location accuracy, 300 eV spectral resolution). The WFM is equipped with an on-board system for bright events (e.g. GRB) localization. The trigger time and position of these events are broadcast to the ground within 30 s from discovery. In this paper we present the status of the mission at the end of its Phase A study.
LOFT, the Large Observatory For X-ray Timing, was one of the ESA M3 mission candidates that completed their
assessment phase at the end of 2013. LOFT is equipped with two instruments, the Large Area Detector (LAD) and the Wide Field Monitor (WFM). The LAD performs pointed observations of several targets per orbit (~90 minutes),
providing roughly ~80 GB of proprietary data per day (the proprietary period will be 12 months). The WFM
continuously monitors about 1/3 of the sky at a time and provides data for about ~100 sources a day, resulting in a total of ~20 GB of additional telemetry. The LOFT Burst alert System additionally identifies on-board bright impulsive events (e.g., Gamma-ray Bursts, GRBs) and broadcasts the corresponding position and trigger time to the ground using a dedicated system of ~15 VHF receivers. All WFM data are planned to be made public immediately. In this contribution we summarize the planned organization of the LOFT ground segment (GS), as established in the mission Yellow Book1. We describe the expected GS contributions from ESA and the LOFT consortium. A review is provided of the planned LOFT data products and the details of the data flow, archiving and distribution. Despite LOFT was not selected for launch within the M3 call, its long assessment phase ( >2 years) led to a very solid mission design and an efficient planning of its ground operations.
The Cherenkov Telescope Array (CTA) observatory will be one of the biggest ground-based very-high-energy (VHE) γ-
ray observatory. CTA will achieve a factor of 10 improvement in sensitivity from some tens of GeV to beyond 100 TeV
with respect to existing telescopes.
The CTA observatory will be capable of issuing alerts on variable and transient sources to maximize the scientific return.
To capture these phenomena during their evolution and for effective communication to the astrophysical community,
speed is crucial. This requires a system with a reliable automated trigger that can issue alerts immediately upon detection
of γ-ray flares. This will be accomplished by means of a Real-Time Analysis (RTA) pipeline, a key system of the CTA
observatory. The latency and sensitivity requirements of the alarm system impose a challenge because of the anticipated
large data rate, between 0.5 and 8 GB/s. As a consequence, substantial efforts toward the optimization of highthroughput
computing service are envisioned.
For these reasons our working group has started the development of a prototype of the Real-Time Analysis pipeline. The
main goals of this prototype are to test: (i) a set of frameworks and design patterns useful for the inter-process
communication between software processes running on memory; (ii) the sustainability of the foreseen CTA data rate in
terms of data throughput with different hardware (e.g. accelerators) and software configurations, (iii) the reuse of nonreal-
time algorithms or how much we need to simplify algorithms to be compliant with CTA requirements, (iv) interface
issues between the different CTA systems. In this work we focus on goals (i) and (ii).
ASTRI is the flagship project of INAF (Italian National Institute for Astrophysics) mainly devoted to the
development of Cherenkov small-size dual-mirror telescopes (SST-2M) in the framework of the international
Cherenkov Telescope Array (CTA) Project. ASTRI SST-2M is an end-to-end prototype including scientific and
technical operations as well as the related data analysis and archiving activities. We present here the ASTRI data
handling and archiving system: it is responsible for both the on-site and off-site data processing and archiving.
All the scientific, calibration, and engineering ASTRI data will be stored and organized in dedicated archives
aimed to provide access to both the monitoring and data analysis systems.
ASTRI (Astrofisica con Specchi a Tecnologia Replicante Italiana) is a Flagship Project financed by the Italian Ministry of Education, University and Research, and led by INAF, the Italian National Institute of Astrophysics. The main goals of the ASTRI project are the realization of an end-to-end prototype of a Small Size Telescope (SST) for the Cherenkov Telescope Array (CTA) in a dual- mirror configuration (SST-2M) and, subsequently, of a mini-array comprising seven SST-2M telescopes. The mini-array will be placed at the final CTA Southern Site, which will be part of the CTA seed array, around which the whole CTA observatory will be developed. The Mini-Array Software System (MASS) will provide a comprehensive set of tools to prepare an observing proposal, to perform the observations specified therein (monitoring and controlling all the hardware components of each telescope), to analyze the acquired data online and to store/retrieve all the data products to/from the archive. Here we present the main features of the MASS and its first version, to be tested on the ASTRI SST-2M prototype that will be installed at the INAF observing station located at Serra La Nave on Mount Etna in Sicily.
The use of large-area, fine-pitch Silicon detectors has demonstrated the feasibility of wide field imaging experiments
requesting very low resources in terms of weight, volume, power and costs. The flying SuperAGILE instrument
is the first such experiment, adopting large-area Silicon microstrip detectors coupled to one-dimensional
coded masks. With less than 10 kg, 12 watt and 0.04 m<sup>3</sup> it provides 6-arcmin angular resolution over >1 sr field
of view. Due to odd operational conditions, SuperAGILE works in the unfavourable energy range 18-60 keV. In
this paper we show that the use of innovative large-area Silicon Drift Detectors allows to design experiments with
arcmin-imaging performance over steradian-wide fields of view, in the energy range 2-50 keV, with spectroscopic
resolution in the range of 300-570 eV (FWHM) at room temperature. We will show the concept, design and
readiness of such an experiment, supported by laboratory tests on large-area prototypes. We will quantify the
expected performance in potential applications on X-ray astronomy missions for the observation and long-term
monitoring of Galactic and extragalactic transient and persistent sources, as well as localization and fine study
of the prompt emission of Gamma-Ray Bursts in soft X-rays.
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 <i>ad-hoc</i> 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.
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. The REMIR camera is composed by a set of
sub systems: the array controller, the cooling system, the temperature and the pressure monitors, the filter wheel
controller, the dither wedge controller. During 2005, a complete re-writing of the REMIR software control system started
in order to optimize the system performances: the new configuration will adopt a client server architecture, where a
supervisor system accepts via socket the data acquisition queries from AQUA (the acquisition data suite), manages the
several components of the camera and the communication with the telescope control system. Here we describe in
particular the philosophy adopted to realize the general control system, the sub systems and the communication
The REM Observatory, recently installed and commissioned at la Silla Observatory Chile, is the first moderate aperture robotic telescope able to cover simultaneously the visible-NIR (0.45-2.3 microns) wavelength range. His very fast pointing and his full robotization makes it an ideal observing facility for fast transients. The high throughput Infrared Camera and the Visible imaging spectrograph simultaneously fed by a dichroic allows to collect high S/N data in an unprecedented large spectral range on a telescope of this size. The REM observatory is an example of a versatile and agile facility necessary complement to large telescopes in fileds in which rapid response and/or target pre-screening are necessary. We give in this paper an overview of the Observatory and its performances with emphasis to the innovative technical solution adopted to reach such performances.
The Rapid Eye Mount (REM) telescope is an ambitious project devoted to the prompt observations, in the optical and Near Infrared (NIR), of Gamma-Ray Bursts (GRBs) whose high energy emission is mainly detected by the Swift satellite. The system is able to immediately react to a GRB alert and perform observations, data reduction and analyses, distributing GRB counterparts in a timescale of tens of seconds. Apart from GRB observations, REM can also drive autonomous observations of a variety of targets as X-ray transients, flare stars, etc. We describe here how REM can manage all these tasks robotically, taking into account environmental and scientific parameters as seeing, visibility, target priority, etc.
During the early Summer 2003, the REM telescope has been installed at La Silla, together with the near infrared camera REM-IR and the optical spectrograph. ROSS. The REM project is a fully automated instrument to follow-up Gamma Ray Burst, triggered mainly by satellites, such as HETE II, INTEGRAL, AGILE and SWIFT. REM-IR will perform high efficiency imaging of the prompt infrared afterglow of GRB and, together with the optical spectrograph ROSS, will cover simultaneously a wide wavelength range, allowing a better understanding of the intriguing scientific case of GRB.
In this paper we present the result of the commissioning phase of the near infrared camera REM-IR, lasted for an extended period of time and currently under the final fine tuning.
Fast ground based simultaneous optical-near infrared observation of gamma-ray bursts (GRBs) is a mandatory priority to understand the physical mechanisms at work in these objects. The REM (Rapid Eye Mount) telescope, recently installed at La Silla (ESO, Chile), is an example of a new generation of small robotic telescopes having the capability to allow simultaneous optical and near infrared photometry and low resolution spectroscopy. The REM Optical Slitless Spectrograph (ROSS) is the optical instrument mounted on REM. ROSS has been attached, in one of the two Nasmyth foci, orthogonally to the optical axis and receives the optical light deflected by a beam splitter (dichroic), which leaves the infrared beam to continue along the optical axis where the infrared camera (REM-IR) is installed. Low resolution optical spectroscopy is obtained using an Amici prism mounted on the same filter wheel where are also mounted the broad-band V, R, I photometric filters. The detector head is a commercial camera hosting a Marconi 1024×1024 CCD chip.
AQuA (Automatic QUick Analysis) is a software designed to manage data
reduction and prompt detection of near infra-red (NIR) afterglows
of GRB triggered by the dedicated instruments onboard satellites and observed with the robotic telescope REM. NIR observations of GRBs early afterglow are of crucial importance for GRBs science, revealing even optical obscured or high redshift events. The core of the pipeline is an algorithm for automatic transient detection, based on a decision tree that is continuously upgraded through a Bayesian estimator (DecOAR). It assigns to every transient candidate different reliability coefficients and delivers an alert when a transient is found above the reliability threshold.
We present the near infrared camera REM-IR that will operate aboard the REM telescope, intended as a fully automated instrument to follow-up Gamma Ray Burst, triggered mainly by satellites, such as HETE II, INTEGRAL, AGILE and SWIFT. REM-IR will perform high efficiency imaging of the prompt infrared afterglow of GRB and, together with the optical spectrograph ROSS, will cover simultaneously a wide wavelength range, allowing a better understanding of the intriguing scientific case of GRB. Due to the scientific and technological requirements of the REM project, some innovative solutions has been adopted in REM-IR.
Observations of the prompt afterglow of Gamma Ray Burst events are unanimously considered of paramount importance for GRB science and cosmology. Such observations at NIR wavelengths are even more promising allowing one to monitor high-z Ly-α absorbed bursts as well as events occurring in dusty star-forming regions. In these pages we present REM (Rapid Eye Mount), a fully robotized fast slewing telescope equipped with a high throughput NIR (Z, J, H, K) camera dedicated to detecting the prompt IR afterglow. REM can discover objects at extremely high redshift and trigger large telescopes to observe them. The REM telescope will simultaneously feed ROSS (REM Optical Slitless spectrograph) via a dichroic. ROSS will intensively monitor the prompt optical continuum of GRB afterglows. The synergy between the REM-IR camera and the Ross spectrograph makes REM a powerful observing tool for any kind of fast transient phenomena. Beside its ambitious scientific goals, REM is also technically challenging since it represent the first attempt to locate a NIR camera on a small telescope providing, with ROSS, unprecedented simultaneous wavelength coverage on a telescope of this size.
AQUA (Automated QUick Analysis) is the fast reduction pipeline of the Near Infra-Red (NIR) images obtained by the REM telescope. REM (Rapid Eye Mount) is a robotic NIR/Optical 60cm telescope for fast detection of early afterglow of Gamma Ray Bursts (GRB). NIR observations of GRBs early afterglow are of crucial importance for GRBs science, revealing even optical obscured or high redshift events. On the technical side, they pose a series of problems: luminous background, bright sources (as the counterparts should be observed few seconds after the satellite trigger) and fast detection force high rate images acquisition. Even if the observational strategy will change during the same event observation depending on the counterpart characteristics, we will start with 1 second exposures at the fastest possible rate. The main guideline in the AQUA pipeline development is to allow such a data rate along all the night with nearly real-time results delivery. AQUA will start from the raw images and will deliver an alert with coordinates, photometry and colors to larger telescopes to allow prompt spectroscopic and polarimetric observations. Very fast processing for the raw 512×512 32bit images and variable sources detection with both sources catalogs and images comparison have been implemented to obtain a processing speed of at least 1 image/sec. AQUA is based on ANSI-C code optimized to run on a dual Athlon Linux PC with careful MMX and SSE instructions utilization.