The Phase A study for the high-resolution spectrograph for the Extremely Large Telescope (ELT-HIRES) has been concluded in late 2017. We present the main outcome for a polarimetric light feed from the intermediate focus (IF) and a Nasmyth focus of the telescope. We conclude that the use of the IF is mandatory for high-precision spectropolarimetry. Among the description of the product tree, we present phase-A level opto-mechanical designs of the subunits, describe the observational and calibration modes, the PSF error budget, and the preliminary FEM structural and earthquake analysis.<p> </p> An update on the development of a ray tracing polarimetric simulator to estimate the instrumental polarization including both the telescope mirrors and the optical elements of the polarimeter is reported. Trade-off strategies and ongoing solutions in view of the Phase B are outlined too.
We introduce the opto-mechanical architecture of a high precision, full Stokes vector, dual-channel polarimeter for the
European Extremely Large Telescope’s High Resolution spectrograph (E-ELT HIRES). It is foreseen to feed two
spectrograph modules simultaneously through the standard Front End subunit located on the Nasmyth platform via two
fiber bundles; one optimized for the optical (BVRI), the other optimized for the infrared (zYJH) bands. The polarimeter
is located below M4 in the f/4.4 intermediate focus, representing the only rotationally symmetric focus available, and is
retractable. We illustrate the strategy of repositioning and aligning the instrument, provided that it has to withstand wind
and earthquake loads and that the PSF is varying in width and position due to the active compensation by the co-phasing
corrections. Preliminary results of its expected polarimetric sensitivity and accuracy are also analyzed for several
configurations of M1 segments and suggest a stunning performance in the intermediate focus with cross talks of the
order of 10<sup>-7</sup> but 10<sup>-2</sup> if it were located in the Nasmyth focus.
XIPE, the X-ray Imaging Polarimetry Explorer, is a mission dedicated to X-ray Astronomy. At the time of
writing XIPE is in a competitive phase A as fourth medium size mission of ESA (M4). It promises to reopen the
polarimetry window in high energy Astrophysics after more than 4 decades thanks to a detector that efficiently
exploits the photoelectric effect and to X-ray optics with large effective area. XIPE uniqueness is time-spectrally-spatially-
resolved X-ray polarimetry as a breakthrough in high energy astrophysics and fundamental physics.
Indeed the payload consists of three Gas Pixel Detectors at the focus of three X-ray optics with a total effective
area larger than one XMM mirror but with a low weight. The payload is compatible with the fairing of the Vega
launcher. XIPE is designed as an observatory for X-ray astronomers with 75 % of the time dedicated to a Guest
Observer competitive program and it is organized as a consortium across Europe with main contributions from
Italy, Germany, Spain, United Kingdom, Poland, Sweden.
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.
During 2013, a new visible camera has been finally installed and tested at the 60cm, robotic REM
telescope in the la Silla Observatory. REM is an Italian, fast-reacting telescope initially designed and built for the
immediate response to GRB automatic alerts, but since the first light in 2003 its usage has been covering a wider
range of astronomical interests. While the IR camera REMIR was reaching the expected limiting magnitudes, the
original ROSS visible camera suffered, since the beginning, of a rather poor performance. We set therefore to
implement a newer optical camera, leading to the design, tests and integration of ROS2, a dichroic-based four
channels imaging camera. The four Sloan-like pass bands are imaged, at the same time, in four quadrants of the
CCD, an Andor multilevel Peltier detector. The tests during the science commissioning show an impressive
improvement in the limiting magnitudes, reaching two magnitudes fainter than ROSS. Here we show the concept,
the tests and the user level product we are now offering at REM.
A number of scientific observations take advantage of the use of robotic, fast pointing telescopes; in particular,
fast reacting small telescopes were especially useful for gamma ray burst follow-up which now require better
performances and greater telescope size. However, increasing telescope size could imply some limitations in
terms of operability and technological solutions. In order to select the best telescope configuration it is necessary
to take into account mechanical set up, pointing strategy, wind effects and the resulting effective costs. This
paper will investigate and compare the characteristics of traditional alt-az and alt-alt telescope configurations
considering also an innovative alt-alt set up to be developed as an alternative to the mainstream layout of present
medium class telescopes. In the alt-alt case the system exploits the heritage of larger telescope projects like LBT,
coupled with a more traditional fork mounted to match the alt-alt kinematics, so obtaining a more stable machine
and minimizing the blind spot limitation.
The X-ray sky in high time resolution holds the key to a number of observables related to fundamental physics,
inaccessible to other types of investigations, such as imaging, spectroscopy and polarimetry. Strong gravity effects, the
measurement of the mass of black holes and neutron stars, the equation of state of ultradense matter are among the
objectives of such observations. The prospects for future, non-focused X-ray timing experiments after the exciting age of
RXTE/PCA are very uncertain, mostly due to the technological limitations that need to be faced to realize experiments
with effective areas in the range of several square meters, meeting the scientific requirements. We are developing large-area
monolithic Silicon drift detectors offering high time and energy resolution at room temperature, with modest
resources and operation complexity (e.g., read-out) per unit area. Based on the properties of the detector and read-out
electronics we measured in laboratory, we built a concept for a realistic unprecedented large mission devoted to X-ray
timing in the energy range 2-30 keV. We show that effective areas in the range of 10-15 square meters are within reach,
by using a conventional spacecraft platform and launcher.
During the last years, a number of telescopes and instruments have been dedicated to the follow-up of GRBs: recent
studies of the prompt emission (see for instance GRB080319B) and of their afterglows, evidenced a series of phenomena
that do not fit very well within the standard fireball model. In those cases, optical observations were fundamental to
distinguish among different emission mechanisms and models. In particular, simultaneous observation in various optical
filters became essential to understand the physics, and we discovered the need to have a detailed high time resolution follow up. Finally, recent observations of the polarization in GRB 090102 clearly indicate the presence of an ordered
magnetic field favoring the electromagnetic outflows models. This is, however, only one case and, in order to detail
properly the model, we need a bit of statistics. But, after the Swift launch, the average observed intensity of GRB
afterglows showed to be lower than thought before. Robotic telescopes, as demonstrated by REM, ROTSE, TAROT, etc.
(but see also the GROND set up) is clearly the winning strategy. Indeed, as we will also briefly discuss later on, the
understanding of the prompt emission mechanism depends on the observations covering the first few hundreds seconds
since the beginning of the event with high temporal resolution. To tackle these problems and track down a realistic
model, we started the conceptual design and phase A study of a 4 meter class, fast-pointing telescope (40 <i>sec</i> on target),
equipped with multichannel imagers, from Visible to Near Infrared (Codevisir/Pathos). In the study we explored all the
different parts of the project, from the telescope to the instrumental suite to data managing and analysis, to the dome and
site issue. Contacts with industry have been fruitful in understanding the actual feasibility of building such a complex
machine and no show stoppers have been identified, even if some critical points should be better addressed in the Phase
B study. In this paper, we present the main results of the feasibility study we performed.
The study of Gamma-ray bursts (GRBs) is a key field to expand our understanding of several astrophysical and
cosmological phenomena. SVOM is a Chinese-French Mission which will permit to detect and rapidly locate
GRBs, in particular those at high redshift, and to study their multiwavelength emission. The SVOM satellite, to
be launched in 2013, will carry wide field instruments operating in the X-/γ-ray band and narrow field optical and
soft X-ray telescopes. Here we describe a small soft X-ray telescope (XIAO) proposed as an Italian contribution
to the SVOM mission. Thanks to a grazing incidence X-ray telescope with effective area of ~120 cm<sup>2</sup> and a
short focal length, coupled to a very compact, low noise, fast read out CCD camera, XIAO can substantially
contribute to the overall SVOM capabilities for both GRB and non-GRB science.
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 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.
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.
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.
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.
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.