Users may download and print one copy of any publication from the public portal for the purpose... more Users may download and print one copy of any publication from the public portal for the purpose of private study or research. You may not further distribute the material or use it for any profit-making activity or commercial gain You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.
We present an INTEGRAL data analysis of the X-ray transient SAX J2103.5+4545 during two outbursts... more We present an INTEGRAL data analysis of the X-ray transient SAX J2103.5+4545 during two outbursts detected in December 2002. The INTEGRAL coordinates and error circle agree with the position of the recently proposed optical counterpart. A power-law plus cutoff model provided a good fit to the 4-150 keV spectrum yielding a photon index of 1.0± 0.1, a cutoff energy E cut = 7.6 ± 2.0 keV and a folding energy E fold = 30.9 ± 2.5 keV. The X-ray luminosity in the 4-150 keV energy range was found to be 6.0 × 10 36 erg s −1 , assuming a distance of 6.5 kpc. This luminosity, together with the derived photon index, indicate that the source is in a bright state. A 354.9 ± 0.5 second pulse period is measured. This value is significantly smaller than previous measurements, indicating a long-term spin-up episode.
Gamma-Ray Bursts (GRBs) are the most energetic explosions in the universe, their optical photon f... more Gamma-Ray Bursts (GRBs) are the most energetic explosions in the universe, their optical photon flux rise very quickly, typically within one minute, then fall off gradually. Hundreds of GRBs optical light curves have been measured since the first discovery of GRB in 1967. However, only a handful of measurements have been made within a minute after the gamma ray signal. Because of this drawback, the short-hard type GRBs and rapid-rising GRBs, which may account for 30% of all GRBs, remain practically unexplored. To reach sub-minute timescales, the Ultra-Fast Flash Observatory (UFFO) uses a rapidly moving mirror to redirect the optical beam instead of slewing the entire spacecraft. The first realization of this concept is UFFO-pathfinder, which is equipped with fast-response Slewing Mirror Telescope (SMT) and a UFFO Burst Alert and Trigger Telescope (UBAT). SMT has a slewing mirror to redirect optical photons into a telescope and then record them by an intensified CCD. UBAT uses coded ...
Astronomy and Astrophysics Supplement Series, 1997
New light curves of the late-type binary system ZZ UMa were obtained during a uvby and Hβ monitor... more New light curves of the late-type binary system ZZ UMa were obtained during a uvby and Hβ monitoring program on low mass eclipsing binaries, that has been carried out in a six year photometric observational program (Clement et al. 1997a, Paper I). The main goal of the program is to obtain accurate absolute parameters for stars in the low and intermediate mass range, in order to improve the Mass-Luminosity Relationship (MLR) at the end of the main sequence. This paper presents a complete analysis of the first uvbyβ light curves of the late-type detached eclipsing binary ZZ UMa. This binary system has been observed during eight campaigns at the Calar Alto Observatory (Almeria, Spain). The activity wave superposed on the eclipse light curve has been estimated, by using a new iterative fitting method (Clement et al. 1997b, Paper II). The interpretation of the wave suggests the existence of two active zones of similar intensity, separated by areas at higher temperature. Once the activity wave was subtracted from the light curves, we adjusted the geometrical solution using the EBOP code. Radiative parameters for both stars have been derived from the light curves. Combining the masses deduced from the radial velocity curves (Popper 1995), with the calculated geometrical and radiative values, we computed the absolute parameters for both components. We can conclude that the system is composed of two main sequence G-type stars with masses, radii and chemical composition similar to the Sun.
Received; accepted Aims. We present the first long-term pulse profile study of the X-ray pulsar S... more Received; accepted Aims. We present the first long-term pulse profile study of the X-ray pulsar SAX J2103.5+4545. Our main goal is to study the pulse shape correlation either with luminosity, time or energy.
Received; accepted Aims. We present the first long-term pulse profile study of the X-ray pulsar S... more Received; accepted Aims. We present the first long-term pulse profile study of the X-ray pulsar SAX J2103.5+4545. Our main goal is to study the pulse shape correlation either with luminosity, time or energy.
Terrestrial Gamma ray Flashes (TGFs) are short bursts of high energy (<40 MeV) photons, produced ... more Terrestrial Gamma ray Flashes (TGFs) are short bursts of high energy (<40 MeV) photons, produced during thunderstorms. A review of TGFs theory and observations is presented by Dwyer et al. (2012). TGFs were first detected using the BATSE experiment on-board the CGRO spacecraft (Fishman et al., 1994). Later, TGFs were recorded by the satellites RHESSI (
The readout system and the trigger algorithm implementation for the UFFO Pathfinder
SPIE Proceedings, 2012
ABSTRACT Since the launch of the SWIFT, Gamma-Ray Bursts (GRBs) science has been much progressed.... more ABSTRACT Since the launch of the SWIFT, Gamma-Ray Bursts (GRBs) science has been much progressed. Especially supporting many measurements of GRB events and sharing them with other telescopes by the Gamma-ray Coordinate Network (GCN) have resulted the richness of GRB events, however, only a few of GRB events have been measured within a minute after the gamma ray signal. This lack of sub-minute data limits the study for the characteristics of the UV-optical light curve of the short-hard type GRB and the fast-rising GRB. Therefore, we have developed the telescope named the Ultra-Fast Flash Observatory (UFFO) Pathfinder, to take the sub-minute data for the early photons from GRB. The UFFO Pathfinder has a coded-mask X-ray camera to search the GRB location by the UBAT trigger algorithm. To determine the direction of GRB as soon as possible it requires the fast processing. We have ultimately implemented all algorithms in field programmable gate arrays (FPGA) without microprocessor. Although FPGA, when compared with microprocessor, is generally estimated to support the fast processing rather than the complex processing, we have developed the implementation to overcome the disadvantage and to maximize the advantage. That is to measure the location as accurate as possible and to determine the location within the sub-second timescale. In the particular case for a accuracy of the X-ray trigger, it requires special information from the satellite based on the UFFO central control system. We present the implementation of the UBAT trigger algorithm as well as the readout system of the UFFO Pathfinder.
One of the key aspects of the upcoming Ultra-Fast Flash Observatory (UFFO) pathfinder for Gamma R... more One of the key aspects of the upcoming Ultra-Fast Flash Observatory (UFFO) pathfinder for Gamma Ray Bursts (GRBs) identification is the UFFO Burst Alert & Trigger Telescope (UBAT). The scientific propose of UBAT is to detect and locate as fast as possible the GRBs in the sky. This is achieved by using a coded mask aperture camera scheme with a wide field of view (FOV) and selecting a X-ray detector of high quantum efficiency and large detection area. This X-ray detector of high quantum efficiency and large detection area is called the UBAT detector. The UBAT detector consists of 48 × 48 Yttrium Oxyorthosilicate (YSO) scintillator crystal arrays and Multi Anode Photomultiplier Tubes (MAPMTs), analog electronics equipped with ASIC chips, digital electronics equipped with Field Programmable Gate Array (FPGA) chips, and a mechanical structure that supports all components of the UBAT detector. The total number of the pixels in the UBAT detector is 2304, and the total effective detection area is 191 cm 2. We will present the design and construction, and performance of the UBAT detector including the responses of the UBAT detector to X-ray sources.
The X-Ray Spectroscopic Explorer (XRASE) has a unique combination of features that will make it p... more The X-Ray Spectroscopic Explorer (XRASE) has a unique combination of features that will make it possible to address many of NASA's scientific goals. These include how galaxy clusters form, the physics and chemistry of the ISM, the heating of stellar coronae, the amount and content of intergalactic baryonic matter, the mass of black holes and the formation of disks and jets in AGN and galactic binaries. XRASE has a thin foil, multilayered telescope with a large collecting area up to 10 keV, especially in the Fe Kα region (1100 cm 2 ). Its microcalorimeter array combines high energy resolution (7 eV at 6 keV) and efficiency with a field-of-view of 26 arcmin 2 . A deep orbit allows for long, continuous observations. Monitoring instruments in the optical (WOM-X), UV (TAUVEX) and hard X-RAY (GRAM) bands will offer exceptional opportunities to make simultaneous multiwavelength observations. Several forthcoming missions have capabilities for high resolution X-Ray spectroscopy. They are compared in Figure and Table . CHANDRA (AXAF) is in orbit, XMM will be launched in early 2000 and ASTRO-E in 2000. CONSTELLATION-X will not be launched before 2007. XRASE has the largest field of view for high resolution spectroscopy of extended sources and, except for CONSTELLATION-X, XRASE has the largest effective area at 6.5 keV (exceeding that of the CHANDRA,
The JEM-X monitor provides X-ray spectra and imaging with arcminute angular resolution in the 3 t... more The JEM-X monitor provides X-ray spectra and imaging with arcminute angular resolution in the 3 to 35 keV band. The good angular resolution and the low energy response of JEM-X plays an important role in the identification of gamma ray sources and in the analysis and scientific interpretation of the combined X-ray and gamma ray data. JEM-X is a coded aperture instrument consisting of two identical, coaligned telescopes. Each of the detectors has a sensitive area of 500 cm 2 , and views the sky through its own coded aperture mask. The two coded masks are inverted with respect to each other and provides an angular resolution of 3 across an effective field of view of about 10 • diameter.
Exploration of the X-ray sky has established X-ray astronomy as a fundamental astrophysical disci... more Exploration of the X-ray sky has established X-ray astronomy as a fundamental astrophysical discipline. While our knowledge of the sky below 10 keV has increased dramatically (∼8 orders of magnitude) by use of grazing incidence optics, we still await a similar improvement above 10 keV, where to date only collimated instruments have been used. Also ripe for exploration is the field of X-ray polarimetry, an unused fundamental tool to understand the physics and morphology of X-ray sources. Here we present a novel mission, the New Hard X-ray Mission (NHXM) that brings together for the first time simultaneous high-sensitivity, hard-X-ray imaging, broadband spectroscopy and polarimetry. NHXM will perform groundbreaking science in key scientific areas, including: black hole cosmic evolution, census and accretion physics; acceleration mechanism and non-thermal emission; physics of matter under extreme conditions. NHXM is designed specifically to address these topics via: broad 0.5-80 (120) keV band for imaging and spectroscopy; 20 arcsec (15 goal) Half Energy Width (HEW) angular resolution at 30 keV; sensitivity limits more than 3 orders of magnitude better than those available in present day instruments; broadband (2-35 keV) imaging polarimetry. In addition, NHXM has the ability to locate and actively monitor sources in different states of activity and to repoint within 1 to 2 h. This mission has been proposed to ESA in response to the Cosmic Vision M3 call. Its satellite configuration and payload subsystems were studied as part of previous national efforts permitting us to design a mature configuration that is compatible with a VEGA launch already by 2020.
The Ultra-Fast Flash Observatory (UFFO) Burst Alert and Trigger Telescope (UBAT) has been designe... more The Ultra-Fast Flash Observatory (UFFO) Burst Alert and Trigger Telescope (UBAT) has been designed and built for the localization of transient X-ray sources such as Gamma Ray Bursts (GRBs). As one of main instruments in the UFFO payload onboard the Lomonosov satellite (hereafter UFFO/Lomonosov), the UBAT's roles are to monitor the X-ray sky, to rapidly locate and track transient sources, and to trigger the slewing of a UV/optical telescope, namely Slewing Mirror Telescope (SMT). The SMT, a pioneering The Lomonosov Mission
Determination of Be ST parameters from uvby-beta photometry and H-alpha equivalent widths
Monthly Notices of the Royal Astronomical Society, 1990
Une methode de determination des indices photometriques uvby des etoiles de type Be, corriges de ... more Une methode de determination des indices photometriques uvby des etoiles de type Be, corriges de l'emission circumstellaire, basee sur les mesures de largeurs equivalentes Hα et la photometrie uvby est presentee. Une estimation des couleurs intrinseques, des parametres astrophysiques fondamentaux et du rougissement interstellaire est realisee pour un echantillon d'etoiles Be, ayant des donnees Hα et uvbyβ, avec cette methode.
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