We present an overview of the development of the end-to-end simulations programs developed for COLIBRI (Catching OpticaL and Infrared BRIght), a 1.3m robotic follow-up telescope of the forthcoming SVOM (Space Variable Object Monitor) mission dedicated to the detection and study of gamma-ray bursts (GRBs). The overview contains a description of the Exposure Time Calculator, Image Simulator and photometric redshift code developed in order to assess the performance of COLIBRI. They are open source Python packages and were developed to be easily adaptable to any optical/ Near-Infrared imaging telescopes. We present the scientific performances of COLIBRI, which allows detecting about 95% of the current GRB dataset. Based on a sample of 500 simulated GRBs, a new Bayesian photometric redshift code predicts a relative photometric redshift accuracy of about 5% from redshift 3 to 7.
COLIBRI is one of the two robotic ground follow-up telescopes for the SVOM (Space Variable Object Monitor) mission dedicated to the study of gamma-ray bursts, allowing determination of precise celestial coordinates of the detected bursts. COLIBRI telescope is a two-mirror Ritchey-Chrétien telescope whose concave primary and convex secondary mirrors have diameters of 1325mm and 485mm respectively. The mirrors are currently manufactured at LAM (Laboratoire d’Astrophysique de Marseille). In this article, the advancement of the work is presented. We also give a global overview and status of the COLIBRI project.
We present in this article some of the techniques applied at the Instituto de Astronomía of the Universidad Nacional Autónoma de México (IA-UNAM) to the mechanical structural design for astronomical instruments. With this purpose we use two recent projects developed by the Instrumentation Department. The goal of this work is to give guidelines about support structures design for achieving a faster and accurate astronomical instruments design. The main guidelines that lead all the design stages for instrument subsystems are the high-level requirements and the overall specifications. From these, each subsystem needs to get its own requirements, specifications, modes of operation, relative position, tip/tilt angles, and general tolerances. Normally these values are stated in the error budget of the instrument. Nevertheless, the error budget is dynamic, it is changing constantly. Depending on the manufacturing accuracy achieved, the error budget is again distributed. That is why having guidelines for structural design helps to know some of the limits of tolerances in manufacture and assembly. The error budget becomes then a quantified way for the interaction between groups; it is the key for teamwork.
CEA and Sofradir have been involved for 7 years in studies related to a large format detector development for science and astronomy applications. These studies are linked with ESA's Near Infrared Large Format Sensor Array roadmap which aims to develop a 2Kx2K large format low flux low noise device. The ALFA (Astronomical Large Focal plane Array) detector is currently at design, manufacturing and validation phase at CEA and Sofradir. This paper will present the very last achievements of the ALFA development with a specific focus on the readout integrated circuit design itself. Features and specification of the 2048x2048 15μm pitch with Source Follower Detector (SFD) input stage will be described. Apart from ESA development, European Commission is also contributing to the large detector development thanks to ASTEROID (AStronomical TEchnology EuROpean Infrared detector Development) program founded by REA (Research European Agency). ASTEROID main objectives are to develop very large raw materials (CdZnTe substrate, HgCdTe epilayer…) compatible with the manufacturing of very large detectors in volume keeping the same level of performance. Organization and status of this program will be presented where high synergy with 2K² ALFA detector are included.
SOXS (Son Of X-Shooter) will be a unique spectroscopic facility for the ESO-NTT 3.5-m telescope in La Silla (Chile), able to cover the optical/NIR band (350-1750 nm). The design foresees a high-efficiency spectrograph with a resolutionslit product of ~4,500, capable of simultaneously observing the complete spectral range 350 - 1750 nm with a good sensitivity, with light imaging capabilities in the visible band. This paper outlines the status of the project.
DDOTI will be a wide-field robotic imager consisting of six 28-cm telescopes with prime focus CCDs mounted on a common equatorial mount. Each telescope will have a field of view of 12 deg2, will have 2 arcsec pixels, and will reach a 10σ limiting magnitude in 60 seconds of r ≈ 18:7 in dark time and r ≈ 18:0 in bright time. The set of six will provide an instantaneous field of view of about 72 deg2. DDOTI uses commercial components almost entirely. The first DDOTI will be installed at the Observatorio Astronómico Nacional in Sierra San Pedro Martír, Baja California, México in early 2017. The main science goals of DDOTI are the localization of the optical transients associated with GRBs detected by the GBM instrument on the Fermi satellite and with gravitational-wave transients. DDOTI will also be used for studies of AGN and YSO variability and to determine the occurrence of hot Jupiters. The principal advantage of DDOTI compared to other similar projects is cost: a single DDOTI installation costs only about US$500,000. This makes it possible to contemplate a global network of DDOTI installations. Such geographic diversity would give earlier access and a higher localization rate. We are actively exploring this option.
We present the Microchannel X-ray Telescope, a new light and compact focussing telescope that will be ying on the Sino-French SVOM mission dedicated to Gamma-Ray Burst science. The MXT design is based on the coupling of square pore micro-channel plates with a low noise pnCCD. MXT will provide an effective area of about 50 cm2, and its point spread function is expected to be better than 3.7 arc min (FWHM) on axis. The estimated sensitivity is adequate to detect all the afterglows of the SVOM GRBs, and to localize them to better then 60 arc sec after five minutes of observation.
The SVOM (Space-based multi-band astronomical Variable Objects Monitor) French-Chinese mission is dedicated to the detection, localization and study of Gamma Ray Bursts (GRBs) and other high-energy transient phenomena. We first present the major principles of the SVOM system including the alert system providing near-real-time GRB localizations to large ground-based telescopes. Then the paper describes the definition of the SVOM payload and more particularly the French payload composed of the ECLAIRs instrument, dedicated to GRB detection and positioning, and the MXT instrument, dedicated to GRB followup observation in soft X-ray band.
The main objective of the Wide Field Monitor (WFM) on the LOFT mission is to provide unambiguous detection of the high-energy sources in a large field of view, in order to support science operations of the LOFT primary instrument, the LAD. The monitor will also provide by itself a large number of results on the timing and spectral behavior of hundreds of galactic compact objects, Active Galactic Nuclei and Gamma-Ray Bursts. The WFM is based on the coded aperture concept where a position sensitive detector records the shadow of a mask projected by the celestial sources. The proposed WFM detector plane, based on Double Sided micro-Strip Silicon Detectors (DSSD), will allow proper 2-dimensional recording of the projected shadows. Indeed the positioning of the photon interaction in the detector with equivalent fine resolution in both directions insures the best imaging capability compatible with the allocated budgets for this telescope on LOFT. We will describe here the overall configuration of this 2D-WFM and the design and characteristics of the DSSD detector plane including its imaging and spectral performances. We will also present a number of simulated results discussing the advantages that this configuration offers to LOFT. A DSSD-based WFM will in particular reduce significantly the source confusion experienced by the WFM in crowded regions of the sky like the Galactic Center and will in general increase the observatory science capability of the mission.
We present the SVOM mission that the Chinese National Space Agency and the French Space Agency have decided to jointly implement. SVOM has been designed to detect, characterise and quickly localise gamma-ray bursts (GRBs) and other types of high-energy transients. For this task the spacecraft will carry two widefield high-energy instruments: ECLAIRs, a hard X-ray imager, and the Gamma-Ray Monitor, a broadband spectrometer. Upon localising a transient, SVOM will quickly slew towards the source and start deep followup observations with two narrow-field telescopes: the Micro-channel X-ray Telescope in X-rays and the Visible Telescope in the visible. The nearly anti-solar pointing of SVOM combined with the fast transmission of GRB positions to the ground in less than 1 minute, will facilitate the observations of SVOM transients by the largest ground based telescopes.
We describe a large-angle survey for fast, optical transients: gamma ray bursts (GRBs), supernovae (SNe), lensed and transiting planets, AGNs and serendipitously found objects. The principal science goals are to obtain light curves for all transients and to obtain redshifts of GRBs and orphan afterglows. The array is called Xian. In conjunction with the gamma-ray satellites, ECLAIRs/SVOM and GLAST, the data will be used to study sources from z=0.1 to >6. The telescope array has 400 Schmidt telescopes, each with ~20 sq. degree focal planes and apertures of ~0.5 meters. The passively cooled, multiple CCD arrays have a total of 16000x16000 pixels, up to 13 readout channels per 1K x 4K CCD and work in TDI mode. The system provides continuous coverage of the circumpolar sky, from the Antarctic plateau, every few seconds. Images averaged over longer time intervals allow searches for the host galaxies of the detected transients, as well as for fainter, longer timescale transients. Complete, data at high time resolution are only stored for selected objects. The telescopes are fixed and use a single filter: there are few (or no) moving parts. Expected detection rates are 0.3 GRBs afterglows per day, >100 orphan afterglows per day and >0.1 blue flashes per day from Type II or Type Ib/c supernovae. On-site computers compare successive images and trigger follow-up observations of selected objects with a co-sited, well-instrumented telescope (optical, IR; spectroscopy, photometry, polarimetry), for rapid follow-up of transients. Precursor arrays with 20-100 square degrees are planned for the purpose of developing trigger software, testing observing strategies and deriving good cost estimates for a full set of telescope units.
A well-adapted spectrograph concept has been developed for the SNAP (SuperNova/Acceleration Probe) experiment. The goal is to ensure proper identification of Type Iz supernovae and to standardize the magnitude of each candidate by determining explosion parameters. The spectrograph is also a key element for the calibration of the science mission. An instrument based on an integral field method with the powerful concept of imager slicing has been designed and is presented in this paper. The spectrograph concept is optimized to have high efficiency and low spectral resolution (R~100), constant through the wavelength range (0.35-1.7μm), adapted to the scientific goals of the mission.
Mission requirements, the baseline design, and optical systems budgets for the SuperNova/Acceleration Probe (SNAP) telescope are presented. SNAP is a proposed space-based experiment designed to study dark energy and alternate explanations of the acceleration of the universe’s expansion by performing a series of complementary systematics-controlled astrophysical measurements. The goals of the mission are a Type Ia supernova Hubble diagram and a wide-field weak gravitational lensing survey. A 2m widefield three-mirror telescope feeds a focal plane consisting of 36 CCDs and 36 HgCdTe detectors and a high-efficiency, low resolution integral field spectrograph. Details of the maturing optical system, with emphasis on structural stability during terrestrial testing as well as expected environments during operations at L2 are discussed. The overall stray light mitigation system, including illuminated surfaces and visible objects are also presented.
We present the baseline telescope design for the telescope for the SuperNova/Acceleration Probe (SNAP) space mission. SNAP’s purpose is to determine expansion history of the Universe by measuring the redshifts, magnitudes, and spectral classifications of thousands of supernovae with unprecedented accuracy. Discovering and measuring these supernovae demand both a wide optical field and a high sensitivity throughout the visible and near IR wavebands. We have adopted the annular-field three-mirror anastigmat (TMA) telescope configuration, whose classical aberrations (including chromatic) are zero. We show a preliminary optmechanical design that includes important features for stray light control and on-orbit adjustment and alignment of the optics. We briefly discuss stray light and tolerance issues, and present a preliminary wavefront error budget for the SNAP Telescope. We conclude by describing some of the design tasks being carried out during the current SNAP research and development phase.
The proposed SuperNova/Acceleration Probe (SNAP) mission will have a two-meter class telescope delivering diffraction-limited images to an instrumented 0.7 square degree field in the visible and near-infrared wavelength regime. The requirements for the instrument suite and the present configuration of the focal plane concept are presented. A two year R&D phase, largely supported by the Department of Energy, is just beginning. We describe the development activities that are taking place to advance our preparedness for mission proposal in the areas of detectors and electronics.
A well-adapted spectrograph concept has been developed for the SNAP (SuperNova/Acceleration Probe) experiment. The goal is to ensure proper identification of Type Ia supernovae and to standardize the magnitude of each candidate by determining explosion parameters. An instrument based on an integral field method with the powerful concept of imager slicing has been designed and is presented in this paper. The spectrograph concept is optimized to have very high efficiency and low spectral resolution (R~100), constant through the wavelength range (0.35-1.7μm), adapted to the scientific goals of the mission.