Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userProvenance as a requirement for large-scale complex astronomical instruments
149
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We developed several pieces of software to enable the tracking of provenance information for the large-scale complex astronomical observatory CTA, the Cherenkov Telescope Array. Such major facilities produce data that will be publicly released to a large community of scientists. There are thus strong requirements to ensure data quality, reliability and trustworthiness. Among those requirements, traceability and reproducibility of the data products have to be included in the development of large projects. Those requirements can be answered by structuring and storing the provenance information for each data product. We followed the Provenance data model, currently discussed at the IVOA, and implemented solutions to collect provenance information during the CTA data processing and the execution of jobs on a work cluster.
rate research
Read More
The volume of data that will be produced by the next generation of astrophysical instruments represents a significant opportunity for making unplanned and unexpected discoveries. Conversely, finding unexpected objects or phenomena within such large volumes of data presents a challenge that may best be solved using computational and statistical approaches. We present the application of a coarse-grained complexity measure for identifying interesting observations in large astronomical data sets. This measure, which has been termed apparent complexity, has been shown to model human intuition and perceptions of complexity. Apparent complexity is computationally efficient to derive and can be used to segment and identify interesting observations in very large data sets based on their morphological complexity. We show, using data from the Australia Telescope Large Area Survey, that apparent complexity can be combined with clustering methods to provide an automated process for distinguishing between images of galaxies which have been classified as having simple and complex morphologies. The approach generalizes well when applied to new data after being calibrated on a smaller data set, where it performs better than tested classification methods using pixel data. This generalizability positions apparent complexity as a suitable machine-learning feature for identifying complex observations with unanticipated features.
Variable-delay Polarization Modulators (VPMs) are currently being implemented in experiments designed to measure the polarization of the cosmic microwave background on large angular scales because of their capability for providing rapid, front-end polarization modulation and control over systematic errors. Despite the advantages provided by the VPM, it is important to identify and mitigate any time-varying effects that leak into the synchronously modulated component of the signal. In this paper, the effect of emission from a $300$ K VPM on the system performance is considered and addressed. Though instrument design can greatly reduce the influence of modulated VPM emission, some residual modulated signal is expected. VPM emission is treated in the presence of rotational misalignments and temperature variation. Simulations of time-ordered data are used to evaluate the effect of these residual errors on the power spectrum. The analysis and modeling in this paper guides experimentalists on the critical aspects of observations using VPMs as front-end modulators. By implementing the characterizations and controls as described, front-end VPM modulation can be very powerful for mitigating $1/f$ noise in large angular scale polarimetric surveys. None of the systematic errors studied fundamentally limit the detection and characterization of B-modes on large scales for a tensor-to-scalar ratio of $r=0.01$. Indeed, $r<0.01$ is achievable with commensurately improved characterizations and controls.
Many astronomical optical systems have the disadvantage of generating curved focal planes requiring flattening optical elements to project the corrected image on flat detectors. The use of these designs in combination with a classical flat sensor implies an overall degradation of throughput and system performances to obtain the proper corrected image. With the recent development of curved sensor this can be avoided. This new technology has been gathering more and more attention from a very broad community, as the potential applications are multiple: from low-cost commercial to high impact scientific systems, to mass-market and on board cameras, defense and security, and astronomical community. We describe here the first concave curved CMOS detector developed within a collaboration between CNRS- LAM and CEA-LETI. This fully-functional detector 20 Mpix (CMOSIS CMV20000) has been curved down to a radius of Rc = 150 mm over a size of 24x32 mm^2 . We present here the methodology adopted for its characterization and describe in detail all the results obtained. We also discuss the main components of noise, such as the readout noise, the fixed pattern noise and the dark current. Finally we provide a comparison with the flat version of the same sensor in order to establish the impact of the curving process on the main characteristics of the sensor.
Since its emergence two decades ago, astrophotonics has found broad application in scientific instruments at many institutions worldwide. The case for astrophotonics becomes more compelling as telescopes push for AO-assisted, diffraction-limited performance, a mode of observing that is central to the next-generation of extremely large telescopes (ELTs). Even AO systems are beginning to incorporate advanced photonic principles as the community pushes for higher performance and more complex guide-star configurations. Photonic instruments like Gravity on the Very Large Telescope achieve milliarcsec resolution at 2000 nm which would be very difficult to achieve with conventional optics. While space photonics is not reviewed here, we foresee that remote sensing platforms will become a major beneficiary of astrophotonic components in the years ahead. The field has given back with the development of new technologies (e.g. photonic lantern, large area multi-core fibres) already finding widespread use in other fields; Google Scholar lists more than 400 research papers making reference to this technology. This short review covers representative key developments since the 2009 Focus issue on Astrophotonics.
The scientific detector systems for the ESO ELT first-light instruments, HARMONI, MICADO, and METIS, together will require 27 science detectors: seventeen 2.5 $mu$m cutoff H4RG-15 detectors, four 4K x 4K 231-84 CCDs, five 5.3 $mu$m cutoff H2RG detectors, and one 13.5 $mu$m cutoff GEOSNAP detector. This challenging program of scientific detector system development covers everything from designing and producing state-of-the-art detector control and readout electronics, to developing new detector characterization techniques in the lab, to performance modeling and final system verification. We report briefly on the current design of these detector systems and developments underway to meet the challenging scientific performance goals of the ELT instruments.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
