Subjects -> ASTRONOMY (Total: 94 journals)
Showing 1 - 46 of 46 Journals sorted alphabetically
Advances in Astronomy     Open Access   (Followers: 51)
Annual Review of Astronomy and Astrophysics     Full-text available via subscription   (Followers: 39)
Annual Review of Earth and Planetary Sciences     Full-text available via subscription   (Followers: 63)
Artificial Satellites     Open Access   (Followers: 23)
Astrobiology     Hybrid Journal   (Followers: 14)
Astronomical & Astrophysical Transactions: The Journal of the Eurasian Astronomical Society     Hybrid Journal   (Followers: 6)
Astronomical Journal     Full-text available via subscription   (Followers: 8)
Astronomical Review     Open Access   (Followers: 4)
Astronomische Nachrichten     Hybrid Journal   (Followers: 4)
Astronomy & Geophysics     Hybrid Journal   (Followers: 48)
Astronomy and Astrophysics     Full-text available via subscription   (Followers: 60)
Astronomy and Astrophysics     Open Access   (Followers: 32)
Astronomy and Computing     Hybrid Journal   (Followers: 2)
Astronomy Letters     Hybrid Journal   (Followers: 22)
Astronomy Reports     Hybrid Journal   (Followers: 15)
Astronomy Studies Development     Open Access   (Followers: 12)
Astroparticle Physics     Hybrid Journal   (Followers: 8)
Astrophysical Bulletin     Hybrid Journal   (Followers: 3)
Astrophysical Journal     Full-text available via subscription   (Followers: 19)
Astrophysical Journal Letters     Full-text available via subscription   (Followers: 14)
Astrophysical Journal Supplement Series     Full-text available via subscription   (Followers: 14)
Astrophysics     Hybrid Journal   (Followers: 29)
Astrophysics and Space Science     Hybrid Journal   (Followers: 46)
Astrophysics and Space Sciences Transactions (ASTRA)     Open Access   (Followers: 56)
Astropolitics: The International Journal of Space Politics & Policy     Hybrid Journal   (Followers: 12)
Celestial Mechanics and Dynamical Astronomy     Hybrid Journal   (Followers: 11)
Chinese Astronomy and Astrophysics     Full-text available via subscription   (Followers: 24)
Colloid Journal     Hybrid Journal   (Followers: 3)
Comptes Rendus Physique     Full-text available via subscription   (Followers: 2)
Computational Astrophysics and Cosmology     Open Access   (Followers: 3)
COSPAR Colloquia Series     Full-text available via subscription   (Followers: 11)
Earth, Moon, and Planets     Hybrid Journal   (Followers: 55)
Earth, Planets and Space     Open Access   (Followers: 74)
EAS Publications Series     Full-text available via subscription   (Followers: 8)
EPL Europhysics Letters     Partially Free   (Followers: 8)
Experimental Astronomy     Hybrid Journal   (Followers: 39)
Expert Opinion on Astronomy and Astrophysics     Open Access   (Followers: 7)
Extreme Life, Biospeology & Astrobiology - International Journal of the Bioflux Society     Full-text available via subscription   (Followers: 6)
Few-Body Systems     Hybrid Journal   (Followers: 1)
Foundations of Physics     Hybrid Journal   (Followers: 41)
Frontiers in Astronomy and Space Sciences     Open Access   (Followers: 12)
Galaxies     Open Access   (Followers: 6)
Globe, The     Full-text available via subscription   (Followers: 4)
Gravitation and Cosmology     Hybrid Journal   (Followers: 4)
Icarus     Hybrid Journal   (Followers: 75)
International Journal of Advanced Astronomy     Open Access   (Followers: 28)
International Journal of Astrobiology     Hybrid Journal   (Followers: 4)
International Journal of Astronomy     Open Access   (Followers: 19)
International Journal of Astronomy and Astrophysics     Open Access   (Followers: 29)
International Journal of Satellite Communications Policy and Management     Hybrid Journal   (Followers: 13)
International Letters of Chemistry, Physics and Astronomy     Open Access   (Followers: 12)
ISRN Astronomy and Astrophysics     Open Access   (Followers: 7)
Journal for the History of Astronomy     Full-text available via subscription   (Followers: 19)
Journal of Astrobiology & Outreach     Open Access   (Followers: 3)
Journal of Astronomical Instrumentation     Open Access   (Followers: 3)
Journal of Astronomical Telescopes, Instruments, and Systems     Hybrid Journal   (Followers: 5)
Journal of Astrophysics     Open Access   (Followers: 26)
Journal of Astrophysics and Astronomy     Open Access   (Followers: 52)
Journal of Atmospheric and Solar-Terrestrial Physics     Hybrid Journal   (Followers: 199)
Journal of Cosmology and Astroparticle Physics     Hybrid Journal   (Followers: 38)
Journal of Geophysical Research : Planets     Full-text available via subscription   (Followers: 179)
Journal of Geophysical Research : Space Physics     Full-text available via subscription   (Followers: 177)
Journal of High Energy Astrophysics     Full-text available via subscription   (Followers: 22)
Kinematics and Physics of Celestial Bodies     Hybrid Journal   (Followers: 10)
KronoScope     Hybrid Journal   (Followers: 1)
Macalester Journal of Physics and Astronomy     Open Access   (Followers: 4)
MNASSA : Monthly Notes of the Astronomical Society of South Africa     Full-text available via subscription   (Followers: 1)
Molecular Astrophysics     Full-text available via subscription   (Followers: 1)
Monthly Notices of the Royal Astronomical Society     Hybrid Journal   (Followers: 14)
Monthly Notices of the Royal Astronomical Society : Letters     Hybrid Journal  
Nature Astronomy     Hybrid Journal   (Followers: 8)
New Astronomy     Hybrid Journal   (Followers: 27)
New Astronomy Reviews     Full-text available via subscription   (Followers: 17)
Nonlinear Dynamics     Hybrid Journal   (Followers: 19)
NRIAG Journal of Astronomy and Geophysics     Open Access   (Followers: 5)
Open Astronomy     Open Access   (Followers: 2)
Physics of the Dark Universe     Open Access   (Followers: 4)
Planetary and Space Science     Hybrid Journal   (Followers: 101)
Planetary Science     Open Access   (Followers: 52)
Proceedings of the International Astronomical Union     Full-text available via subscription   (Followers: 2)
Publications of the Astronomical Society of Australia     Hybrid Journal   (Followers: 2)
Publications of the Astronomical Society of Japan     Hybrid Journal   (Followers: 3)
Publications of the Astronomical Society of the Pacific     Full-text available via subscription   (Followers: 4)
Research & Reviews : Journal of Space Science & Technology     Full-text available via subscription   (Followers: 17)
Research in Astronomy and Astrophysics     Full-text available via subscription   (Followers: 29)
Revista Mexicana de Astronomía y Astrofísica     Open Access   (Followers: 2)
Science China Physics, Mechanics & Astronomy     Hybrid Journal   (Followers: 4)
Solar Physics     Hybrid Journal   (Followers: 34)
Solar System Research     Hybrid Journal   (Followers: 14)
Space Science International     Open Access   (Followers: 193)
Space Science Reviews     Hybrid Journal   (Followers: 97)
Space Weather     Full-text available via subscription   (Followers: 24)
Transport and Aerospace Engineering     Open Access   (Followers: 13)
Universe     Open Access   (Followers: 5)
Similar Journals
Journal Cover
Experimental Astronomy
Journal Prestige (SJR): 0.908
Citation Impact (citeScore): 2
Number of Followers: 39  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1572-9508 - ISSN (Online) 0922-6435
Published by Springer-Verlag Homepage  [2626 journals]
  • Experimental evaluation of complete safe coordination of astrobots for
           Sloan Digital Sky Survey V
    • Abstract: Abstract The data throughput of massive spectroscopic surveys in the course of each observation is directly coordinated with the number of optical fibers which reach their target. In this paper, we evaluate the safety and the performance of the astrobots coordination in SDSS-V by conducting various experimental and simulated tests. We illustrate that our strategy provides a complete coordination condition which depends on the operational characteristics of astrobots, their configurations, and their targets. Namely, a coordination method based on the notion of cooperative artificial potential fields is used to generate safe and complete trajectories for astrobots. Optimal target assignment further improves the performance of the used algorithm in terms of faster convergences and less oscillatory movements. Both random targets and galaxy catalog targets are employed to observe the coordination success of the algorithm in various target distributions. The proposed method is capable of handling all potential collisions in the course of coordination. Once the completeness condition is fulfilled according to initial configuration of astrobots and their targets, the algorithm reaches full convergence of astrobots. Should one assign targets to astrobots using efficient strategies, convergence time as well as the number of oscillations decrease in the course of coordination. Rare incomplete scenarios are simply resolved by trivial modifications of astrobots swarms’ parameters.
      PubDate: 2020-12-19
       
  • Ariel – a window to the origin of life on early earth'
    • Abstract: Abstract Is there life beyond Earth' An ideal research program would first ascertain how life on Earth began and then use this as a blueprint for its existence elsewhere. But the origin of life on Earth is still not understood, what then could be the way forward' Upcoming observations of terrestrial exoplanets provide a unique opportunity for answering this fundamental question through the study of other planetary systems. If we are able to see how physical and chemical environments similar to the early Earth evolve we open a window into our own Hadean eon, despite all information from this time being long lost from our planet’s geological record. A careful investigation of the chemistry expected on young exoplanets is therefore necessary, and the preparation of reference materials for spectroscopic observations is of paramount importance. In particular, the deduction of chemical markers identifying specific processes and features in exoplanetary environments, ideally “uniquely”. For instance, prebiotic feedstock molecules, in the form of aerosols and vapours, could be observed in transmission spectra in the near future whilst their surface deposits could be observed from reflectance spectra. The same detection methods also promise to identify particular intermediates of chemical and physical processes known to be prebiotically plausible. Is Ariel truly able to open a window to the past and answer questions concerning the origin of life on our planet and the universe' In this paper, we discuss aspects of prebiotic chemistry that will help in formulating future observational and data interpretation strategies for the Ariel mission. This paper is intended to open a discussion and motivate future detailed laboratory studies of prebiotic processes on young exoplanets and their chemical signatures.
      PubDate: 2020-11-25
       
  • Ground calibration of Solar X-ray Monitor on board the Chandrayaan-2
           orbiter
    • Abstract: Abstract Chandrayaan-2, the second Indian mission to the Moon, carries a spectrometer called the Solar X-ray Monitor (XSM) to perform soft X-ray spectral measurements of the Sun while a companion payload, CLASS, measures the fluorescence emission from the Moon. Together these two payloads will provide quantitative estimates of elemental abundances on the lunar surface. The XSM with its high time cadence and high energy resolution spectral measurements, is also expected to provide significant contributions to solar X-ray studies. For this purpose, the XSM employs a Silicon Drift Detector and carries out energy measurements of incident photons in the 1 – 15 keV range with a resolution of < 180 eV at 5.9 keV, over a wide range of solar X-ray intensities. Extensive ground calibration experiments have been carried out with the XSM using laboratory X-ray sources as well as X-ray beam-line facilities to determine the instrument response matrix parameters required to carry out quantitative spectral analysis. This includes measurements, under various observing conditions, of gain, spectral redistribution function, and effective area. The capability of the XSM to maintain its spectral performance at high incident flux as well as its dead-time and pile-up characteristics have also been investigated. The results of these ground calibration experiments of the XSM payload are presented in this article.
      PubDate: 2020-11-25
       
  • Study of particle multiplicity of cosmic ray events using 2 m × 2 m
           resistive plate chamber stack at IICHEP-Madurai
    • Abstract: Abstract An experimental setup consisting of 12 layers of glass Resistive Plate Chambers (RPCs) of size 2 m × 2 m has been built at IICHEP-Madurai (9∘56 \(^{\prime }\) 14.5 \(^{\prime \prime }\) N 78∘0 \(^{\prime }\) 47.9 \(^{\prime \prime }\) E) to study the long term performance and stability of RPCs produced on a large scale in Indian industry. This setup has been collecting data triggered by the passage of charged particles. The measurement of the multiplicity of charged particles due to cosmic ray interactions are presented here. Finally, the results are compared with different hadronic models of the CORSIKA simulation.
      PubDate: 2020-11-19
       
  • Simulations of orbital debris clouds due to breakup events and their
           characterisation using the Murchison Widefield Array radio telescope
    • Abstract: Abstract In this paper we consider the use of wide field of view radar sensors such as the Murchison Widefield Array (MWA), a low frequency radio telescope designed for astrophysics and cosmology, for rapid response observations of the debris clouds produced by collisions between objects in Earth orbit. With an increasing density of objects in Low Earth Orbit, including legacy assets used by the astronomy community over decades, the risk of new debris clouds forming is also increasing. The MWA constitutes a wide field, rapid response passive radar system and we explore its likely performance in the detection and characterisation of debris clouds. In general, astronomy facilities such as the MWA can play a role in protecting the space environment for the future. In order to undertake this work, we adapt the NASA EVOLVE 4.0 breakup model, utilising the EVOLVE outputs to produce representative dynamic debris clouds. We find that the MWA is likely to detect a large fraction (> 70%) of modelled debris cloud fragments for collision masses between 100 kg and 1000 kg for orbits in the lower part of LEO, if the MWA can achieve close to optimal detection sensitivity. Useful detection fractions are still achieved for more conservative assumptions. The detection fraction of fragments decreases as a function of altitude and inversely with collision mass. Encouragingly, we find that the wide field nature of the MWA allows the full evolving debris clouds to be observed in a single observation, with only ∼2% of the debris fragments escaping the sensitive portion of the field of view after 100 seconds, for all collision masses and altitudes. These results show that the MWA is an intrinsically useful facility for the rapid characterisation of debris clouds, but that work is required to achieve the data processing within an appropriate timeframe to provide rapid alerts.
      PubDate: 2020-11-15
       
  • Technologies for tunable gamma-ray lenses
    • Abstract: Abstract The tunable gamma-ray lens has turned out to be a promising alternative to the classical fixed-energy Laue-lenses discussed in the past. We describe here our development work on a miniature pedestal with one-axis tilt adjustment. We also outline our design for an optical system, capable of monitoring the alignment of the many crystals needed. An added benefit of the tunable crystal pedestal is that it relieves both the demands for high precision in the crystal mounting and the stringent requirements for long-term stability of the support platform on which the crystals are mounted. Moreover, mounting the individual crystals on separate pedestals facilitates the use of double layers of crystals.
      PubDate: 2020-11-09
       
  • The CHEOPS mission
    • Abstract: Abstract The CHaracterising ExOPlanet Satellite (CHEOPS) was selected on October 19, 2012, as the first small mission (S-mission) in the ESA Science Programme and successfully launched on December 18, 2019, as a secondary passenger on a Soyuz-Fregat rocket from Kourou, French Guiana. CHEOPS is a partnership between ESA and Switzerland with important contributions by ten additional ESA Member States. CHEOPS is the first mission dedicated to search for transits of exoplanets using ultrahigh precision photometry on bright stars already known to host planets. As a follow-up mission, CHEOPS is mainly dedicated to improving, whenever possible, existing radii measurements or provide first accurate measurements for a subset of those planets for which the mass has already been estimated from ground-based spectroscopic surveys. The expected photometric precision will also allow CHEOPS to go beyond measuring only transits and to follow phase curves or to search for exo-moons, for example. Finally, by unveiling transiting exoplanets with high potential for in-depth characterisation, CHEOPS will also provide prime targets for future instruments suited to the spectroscopic characterisation of exoplanetary atmospheres. To reach its science objectives, requirements on the photometric precision and stability have been derived for stars with magnitudes ranging from 6 to 12 in the V band. In particular, CHEOPS shall be able to detect Earth-size planets transiting G5 dwarf stars (stellar radius of 0.9R⊙) in the magnitude range 6 ≤ V ≤ 9 by achieving a photometric precision of 20 ppm in 6 hours of integration time. In the case of K-type stars (stellar radius of 0.7R⊙) of magnitude in the range 9 ≤ V ≤ 12, CHEOPS shall be able to detect transiting Neptune-size planets achieving a photometric precision of 85 ppm in 3 hours of integration time. This precision has to be maintained over continuous periods of observation for up to 48 hours. This precision and stability will be achieved by using a single, frame-transfer, back-illuminated CCD detector at the focal plane assembly of a 33.5 cm diameter, on-axis Ritchey-Chrétien telescope. The nearly 275 kg spacecraft is nadir-locked, with a pointing accuracy of about 1 arcsec rms, and will allow for at least 1 Gbit/day downlink. The sun-synchronous dusk-dawn orbit at 700 km altitude enables having the Sun permanently on the backside of the spacecraft thus minimising Earth stray light. A mission duration of 3.5 years in orbit is foreseen to enable the execution of the science programme. During this period, 20% of the observing time is available to the wider community through yearly ESA call for proposals, as well as through discretionary time approved by ESA’s Director of Science. At the time of this writing, CHEOPS commissioning has been completed and CHEOPS has been shown to fulfill all its requirements. The mission has now started the execution of its science programme.
      PubDate: 2020-11-05
       
  • Wide band, tunable gamma-ray lenses
    • Abstract: Abstract A new concept for an astronomical telescope in the MeV energy band is presented. The concept builds on Bragg diffraction in crystals, which has been discussed in the past, but so far a design with good sensitivity over a wide energy range has seemed out of reach. In this paper we point out that if we find ways to adjust, in orbit, the individual tilt of all the crystals in the lens this would allow one single lens to cover with excellent efficiency the full range of energies from 200 keV to 2.5 MeV in a few observation steps. Secondly, we note that the use of lenses with double crystal layers will increase the photon collection significantly. In an accompanying paper we describe our overall lens design in more detail and present our first prototype tilt adjustment pedestal for use with the individual lens facets.
      PubDate: 2020-11-03
       
  • Expanding the field of view: station design for the AAMID SKA radio
           telescope
    • Abstract: Abstract The new generation radio telescopes, such as the Square Kilometre Array (SKA) currently under construction, will use aperture array, technology for the low frequency regime. For SKA2, the second phase scheduled after the realization of SKA1, aperture array technology is proposed up to 1.4 GHz. The antenna element count, as well as the signal processing cost, of such a system will be high. In this paper we analyze an option to reduce the number of antenna elements by making the array sparse. To reduce the signal processing cost Fast Fourier Transform Beamforming is proposed and it performance is compared to traditional beamforming. To guide the system design a Figure of Merit for the performance cost ratio is proposed and evaluated for various levels of sparsity of the antenna array. It is concluded that, for equal front-end and back-end costs, a sparse system is only marginally better than a dense system. Only when signal processing cost is significantly lower than the front-end hardware, a sparse system can be competitive.
      PubDate: 2020-10-21
       
  • First light of SOVAG, a spectrograph for visible and near-infrared
           observation of asteroids
    • Abstract: Abstract Spectroscopy in the visible and near-infrared has been the main tool for characterising the surface properties of asteroids for decades. For a given target, the two wavelength regimes are usually acquired by different telescopes/instruments, separated by years. They are seldom obtained simultaneously. However, it is not straightforward to combine datasets from different sources because of the spectral reddening linked with phase angle. We present the first-light result of SOVAG (Spectrographe pour l’Observations dans le Visible et infrarouge proche d’Astéroïdes Géocroiseurs), a new concept of spectrograph for observing both wavelength ranges at the same time. It is compact in design and portable. We developed a prototype of this instrument between 2016 and 2018. In July 2018, we mounted SOVAG on the 1 m-telescope in Pic du Midi observatory (for which it was designed) and conducted its on-sky first light experiment. We present a spectrum of (4) Vesta which demonstrates the reliability of observations and the accuracy of the calibration. Ongoing development will allow us to push observation-limits toward fainter objects.
      PubDate: 2020-10-15
       
  • Scatter due to Ultraviolet (UV) photopolymerization of molecular
           contamination on optical surfaces
    • Abstract: Abstract Molecular contamination on optical surfaces is a serious issue for space payloads. For ultraviolet (UV) payloads, molecular contamination results in loss of throughput. Whereas, for visible (VIS) payloads loss of throughput due to molecular contamination is not very critical. However, UV photopolymerization of molecular contamination can create serious problems to VIS payloads with stringent scatter requirements. Visible Emission Line Coronagraph (VELC) on board ADITYA-L1 mission is one of them. For such payloads, quantifying the effect of molecular contamination in terms of scattered light is very critical. To do the same, UV exposure studies are carried out on optical surfaces with different levels of molecular contamination. Contamination levels are defined by the weight and mass loss of the contaminant. UV dosage levels on the optical surfaces is determined by the number of hours of UV exposure and UV irradiance levels. Variation in the scatter from the optical surfaces is measured pre and post UV exposures. Contaminated optical samples are exposed to the UV radiation levels equivalent to 125 days of mission life. Substantial increase in the scatter of the contaminated samples is observed due to the UV exposure. Increase in scatter is more rapid in the initial mission days (up to 45 days). This paper elaborates the experiments carried out and discusses the results from them.
      PubDate: 2020-10-13
       
  • ArielRad: the Ariel radiometric model
    • Abstract: Abstract ArielRad, the Ariel radiometric model, is a simulator developed to address the challenges in optimising the space mission science payload and to demonstrate its compliance with the performance requirements. Ariel, the Atmospheric Remote-Sensing Infrared Exoplanet Large-survey, has been selected by ESA as the M4 mission in the Cosmic Vision programme and, during its 4 years primary operation, will provide the first unbiased spectroscopic survey of a large and diverse sample of transiting exoplanet atmospheres. To allow for an accurate study of the mission, ArielRad uses a physically motivated noise model to estimate contributions arising from stationary processes, and includes margins for correlated and time-dependent noise sources. We show that the measurement uncertainties are dominated by the photon statistic, and that an observing programme with about 1000 exoplanetary targets can be completed during the primary mission lifetime.
      PubDate: 2020-10-13
       
  • CAPTURE: a continuum imaging pipeline for the uGMRT
    • Abstract: Abstract We present the first fully automated pipeline for making images from the interferometric data obtained from the upgraded Giant Metrewave Radio Telescope (uGMRT) called CAsa Pipeline-cum-Toolkit for Upgraded Giant Metrewave Radio Telescope data REduction - CAPTURE. It is a python program that uses tasks from the NRAO Common Astronomy Software Applications (CASA) to perform the steps of flagging of bad data, calibration, imaging and self-calibration. The salient features of the pipeline are: i) a fully automatic mode to go from the raw data to a self-calibrated continuum image, ii) specialized flagging strategies for short and long baselines that ensure minimal loss of extended structure, iii) flagging of persistent narrow band radio frequency interference (RFI), iv) flexibility for the user to configure the pipeline for step-by-step analysis or special cases and v) analysis of data from the legacy GMRT. CAPTURE is available publicly on github (https://github.com/ruta-k/uGMRT-pipeline, release v1.0.0). The primary beam correction for the uGMRT images produced with CAPTURE is made separately available at https://github.com/ruta-k/uGMRTprimarybeam. We show examples of using CAPTURE on uGMRT and legacy GMRT data. In principle, CAPTURE can be tailored for use with other radio interferometric data.
      PubDate: 2020-10-12
       
  • Design of Pocket-GMT: an optical emulation of the Giant Magellan Telescope
    • Abstract: Abstract The concept design for a laboratory based telescope emulator for the Giant Magellan Telescope (GMT) is described here. The Giant Magellan Telescope has a primary mirror comprised of 7 segments, and a secondary mirror with matching segmentation. The phasing of the GMT is a complex problem; a phasing testbed, Pocket-GMT, has been designed by a group within the Research School of Astronomy and Astrophysics at the Australian National University for the Giant Magellan Telescope Corporation. Pocket-GMT uses a novel technique to split the bending modes between a piston/tip-tilt surface and a deformable mirror. Pocket-GMT will demonstrate successful phasing of an optical miniature GMT by the planned prototype wavefront sensing systems. By reproducing the optical characteristics of the GMT on a small scale, Pocket-GMT will reduce the risk associated with the phasing system and provide a platform to test the telescopeFLs instrumentation prior to commissioning.
      PubDate: 2020-10-06
       
  • CHESS: An innovative concept for high-resolution, far-UV spectroscopy
    • Abstract: Abstract The space ultraviolet (UV) is a critical astronomical observing window, where a multitude of atomic, ionic, and molecular signatures provide crucial insight into planetary, interstellar, stellar, intergalactic, and extragalactic objects. The next generation of large space telescopes require highly sensitive, moderate-to-high resolution UV spectrograph. However, sensitive observations in the UV are difficult, as UV optical performance and imaging efficiencies have lagged behind counterparts in the visible and infrared regimes. This has historically resulted in simple, low-bounce instruments to increase sensitivity. In this study, we present the design, fabrication, and calibration of a simple, high resolution, high throughput FUV spectrograph - the Colorado High-resolution Echelle Stellar Spectrograph (CHESS). CHESS is a sounding rocket payload to demonstrate the instrument design for the next-generation UV space telescopes. We present tests and results on the performance of several state-of-the-art diffraction grating and detector technologies for FUV astronomical applications that were flown aboard the first two iterations of CHESS. The CHESS spectrograph was used to study the atomic-to-molecular transitions within translucent cloud regions in the interstellar medium (ISM) through absorption spectroscopy. The first two flights looked at the sightlines towards α Virgo and ' Persei and flight results are presented.
      PubDate: 2020-10-01
       
  • End to end simulators: a flexible and scalable cloud-based architecture
    • Abstract: Abstract Simulations of frames from existing and upcoming high-resolution spectrographs, targeted for high accuracy radial velocity measurements, are computationally demanding (both in time and space). We present in this paper an innovative approach based on both parallelization and distribution of the workload. By using NVIDIA CUDA custom-made kernels and state-of-the-art cloud-computing architectures in a Platform as a Service (PaaS) approach, we implemented a modular and scalable end-to-end simulator that is able to render synthetic frames with an accuracy of the order of few cm/sec, while keeping the computational time low. We applied our approach to two spectrographs. For VLT-ESPRESSO we give a sound comparison between the actual data and the simulations showing the obtained spectral formats and the recovered instrumental profile. We also simulate data for the upcoming HIRES at the ELT and investigate the overall performance in terms of computational time and scalability against the size of the problem. In addition we demonstrate the interface with data-reduction systems and we preliminary show that the data can be reduced successfully by existing methods.
      PubDate: 2020-09-21
       
  • Energy sensitivity of the GRAPES-3 EAS array for primary cosmic ray
           protons
    • Abstract: Abstract Low energy ground-based cosmic ray air shower experiments generally have energy threshold in the range of a few tens to a few hundreds of TeV. The shower observables are measured indirectly with an array of detectors. The atmospheric absorption of low energy secondaries limits their detection frequencies at the Earth’s surface. However, due to selection effects, a tiny fraction of low energy showers, which are produced in the lower atmosphere can reach the observational level. But, due to less information of shower observables, the reconstruction of these showers are arduous. Hence, it is believed that direct measurements by experiments aboard on satellites and balloon flights are more reliable at low energies. Despite having very small efficiency ( \(\sim \) 0.1%) at low energies, the large acceptance ( \(\sim \) 5m2sr) of GRAPES-3 experiment allows observing primary cosmic rays down below to \(\sim \) 1TeV and opens up the possibility to measure primary energy spectrum spanning from a few TeV to beyond cosmic ray knee (up to 1016eV), covering five orders of magnitude. The GRAPES-3 energy threshold for primary protons through Monte Carlo simulations are calculated, which gives reasonably good agreement with data. Furthermore, the total efficiencies and acceptance are also calculated for protons primaries. The ability of GRAPES-3 experiment to cover such a broader energy range may provide a unique handle to bridge the energy spectrum between direct measurements at low energies and indirect measurements at ultra-high energies.
      PubDate: 2020-09-12
       
  • Mapper of Narrow Galaxy Lines (MaNGaL): new tunable filter imager for
           Caucasian telescopes
    • Abstract: Abstract We described the design and operation principles of a new tunable-filter photometer developed for the 1-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences and the 2.5-m telescope of the Sternberg Astronomical Institute of the Moscow State University. The instrument is mounted on the scanning Fabry-Perot interferometer operating in the tunable-filter mode in the spectral range of 460-800 nm with a typical spectral resolution of about 1.3 nm. It allows one to create images of galactic and extragalactic nebulae in the emission lines having different excitation conditions and to carry out diagnostics of the gas ionization state. The main steps of observations, data calibration, and reduction are illustrated by examples of different emission-line objects: galactic H ii regions, planetary nebulae, active galaxies with extended filaments, starburst galaxies, and Perseus galaxy cluster.
      PubDate: 2020-09-03
       
  • Photometry of exoplanetary transits at Osservatorio Polifunzionale del
           Chianti
    • Abstract: Abstract In this paper we report the observations of HD189733b, Kepler-41b, Kepler-42b, GJ 436b, WASP-77ab, HAT-P-32b and EPIC 211818569 as measured at the Osservatorio Polifunzionale del Chianti, a new astro-nomical site in Italy. Commissioning observing runs have been done in order to test capabilities, systematics and limits of the system and to improve its accuracy. For this purpose, a software algorithm has been developed to estimate the differential photometric error of any transit observation, so that the integration time can be chosen to reach optimal signal-to-noise ratios, and to obtain a picture of what kind of transits this setup can reveal. Currently, the system is able to reach an accuracy of about 1 mmag and so it is ready for the much needed exoplanetary transit follow-up.
      PubDate: 2020-08-31
       
  • Design of a hybrid refractive-diffractive telescope for observations in UV
    • Abstract: Abstract Telescopes are one of the common types of satellite payloads. They are used both for Earth and astronomical observations. By using space telescopes it is possible to eliminate the negative effect of the atmosphere on image quality. Additionally, observations in some spectral ranges can be performed only from space due to absorption of certain wavelengths in the atmosphere. One such range is UV below 300 nm, which is of particular interest when it comes to the investigation of hot objects. Reflective telescopes are commonly used in this spectral range, although many classical designs are limited in their useful field of view to values below 1°. In this paper a hybrid refractive-diffractive telescope design working in a 200 nm – 300 nm spectral range with a field of view 10°×10° is proposed. Its performance is compared to purely refractive and reflective systems and significant improvement in the imaging quality of the system and decrease of its size is shown. The choice of the diffractive element type is explained. Parameters of the systems are based on the requirements for a proposed Polish mission UVSat which aims to enable long-term observations of a large number of stars exhibiting UV variance.
      PubDate: 2020-07-19
       
 
JournalTOCs
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
Email: journaltocs@hw.ac.uk
Tel: +00 44 (0)131 4513762
 


Your IP address: 3.232.133.141
 
Home (Search)
API
About JournalTOCs
News (blog, publications)
JournalTOCs on Twitter   JournalTOCs on Facebook

JournalTOCs © 2009-