The INTEGRAL spacecraft – in-orbit performance

Jensen, Peter; Clausen, K.; Cassi, C.; Ravera, F.; Janin, G.; Winkler, Christoph; Much, R.

doi:10.1051/0004-6361:20031173

Cited by 69 publications

(62 citation statements)

References 3 publications

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“…The spacecraft (Jensen et al 2003) consists of a service module (bus) containing all spacecraft subsystems and a payload module containing the scientific instruments. The service module has been developed in parallel for two ESA scientific missions, INTEGRAL and XMM-Newton.…”

Section: Mission Overviewmentioning

confidence: 99%

The INTEGRAL mission

Winkler

Courvoisier

Cocco

et al. 2003

A&A

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886

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Abstract. The ESA observatory INTEGRAL (International Gamma-Ray Astrophysics Laboratory) is dedicated to the fine spectroscopy (2.5 keV FWHM @ 1 MeV) and fine imaging (angular resolution: 12 arcmin FWHM) of celestial gamma-ray sources in the energy range 15 keV to 10 MeV with concurrent source monitoring in the X-ray (3−35 keV) and optical (Vband, 550 nm) energy ranges. INTEGRAL carries two main gamma-ray instruments, the spectrometer SPI (Vedrenne et al. (until June 2003) reaches ∼1800 ks in the Galactic plane. The prospects are excellent for the scientific community to observe the high energy sky using state-of-the-art gamma-ray imaging and spectroscopy. This paper presents a high-level overview of INTEGRAL.

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Section: Mission Overviewmentioning

confidence: 99%

The INTEGRAL mission

Winkler

Courvoisier

Cocco

et al. 2003

A&A

Self Cite

1,215

886

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“…Operating in the 20 keV-8 MeV band, SPI uses germanium detectors to provide high spectral resolution while imaging is performed through the coded mask technique (Roques et al 2003). The observational strategy of the INTE-GRAL mission is to sample the region of interest by means of 30-40 minute long fixed pointings (the so-called science windows), each separated by a 2 • angular distance (see Jensen et al 2003 for details). In order to extend the spectral coverage to lower energies, we also considered simultaneous 4-28 keV data from the Proportional Counter Array (PCA) on RXTE (Bradt et al 1993).…”

Section: Instrumentsmentioning

confidence: 99%

Variability and Spectral Modeling of the Hard X-Ray Emission of Gx 339–4 in a Bright Low/Hard State

Droulans

Belmont

Malzac

et al. 2010

ApJ

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We study the high-energy emission of the Galactic black hole candidate GX 339−4 using INTEGRAL/SPI and simultaneous RXTE/PCA data. By the end of 2007 January, when it reached its peak luminosity in hard X-rays, the source was in a bright hard state. The SPectrometer on INTEGRAL (SPI) data from this period show a good signal-to-noise ratio, allowing a detailed study of the spectral energy distribution up to several hundred keV. As a main result, we report on the detection of a variable hard spectral feature ( 150 keV) which represents a significant excess with respect to the cutoff power-law shape of the spectrum. The SPI data suggest that the intensity of this feature is positively correlated with the 25-50 keV luminosity of the source and the associated variability timescale is shorter than 7 hr. The simultaneous Proportional Counter Array data, however, show no significant change in the spectral shape, indicating that the source is not undergoing a canonical state transition. We analyzed the broadband spectra in the lights of several physical models, assuming different heating mechanisms and properties of the Comptonizing plasma. For the first time, we performed quantitative model fitting with the new versatile Comptonization code belm, accounting self-consistently for the presence of a magnetic field. We show that a magnetized medium subject to pure non-thermal electron acceleration provides a framework for a physically consistent interpretation of the observed 4-500 keV emission. Moreover, we find that the spectral variability might be triggered by the variations of only one physical parameter, namely the magnetic field strength. Therefore, it appears that the magnetic field is likely to be a key parameter in the production of the Comptonized hard X-ray emission.

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“…An appropriate dithering strategy (Jensen et al, 2003) has been used where the spacecraft continuously follows a dithering pattern throughout an observation. In general, the pointing direction varies around a target by steps of 2…”

Section: Dithering and Sources Variabilitymentioning

confidence: 99%

“…The telescope is dedicated to the analysis of both point-sources and diffuse emissions, with a high energy resolution (Vedrenne et al, 2003). Its imaging capabilities rely on a coded-mask aperture and a specific observation strategy based on a dithering procedure (Jensen et al, 2003). After several years of operation, it also becomes important to be able to handle simultaneously all the data, in order, for example, to ✩ Based on observations with INTEGRAL, an ESA project with instruments and science data center funded by ESA member states (especially the PI countries: Denmark, France, Germany, Italy, Spain, and Switzerland), Czech Republic and Poland with participation of Russia and the USA.…”

Section: Introductionmentioning

confidence: 99%

Simultaneous analysis of large INTEGRAL/SPI11Based on observations with INTEGRAL, an ESA project with instruments and science data center funded by ESA member states (especially the PI countries: Denmark, France, Germany, Italy, Spain, and Switzerland), Czech Republic and Poland with participation of Russia and the USA. datasets: Optimizing the computation of the solution and its variance using sparse matrix algorithms

Bouchet¹,

Amestoy²,

Buttari³

et al. 2013

Astronomy and Computing

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Nowadays, analyzing and reducing the ever larger astronomical datasets is becoming a crucial challenge, especially for long cumulated observation times. The INTEGRAL/SPI X/γ-ray spectrometer is an instrument for which it is essential to process many exposures at the same time in order to increase the low signal-to-noise ratio of the weakest sources. In this context, the conventional methods for data reduction are inefficient and sometimes not feasible at all. Processing several years of data simultaneously requires computing not only the solution of a large system of equations, but also the associated uncertainties. We aim at reducing the computation time and the memory usage. Since the SPI transfer function is sparse, we have used some popular methods for the solution of large sparse linear systems; we briefly review these methods. We use the Multifrontal Massively Parallel Solver (MUMPS) to compute the solution of the system of equations. We also need to compute the variance of the solution, which amounts to computing selected entries of the inverse of the sparse matrix corresponding to our linear system. This can be achieved through one of the latest features of the MUMPS software that has been partly motivated by this work. In this paper we provide a brief presentation of this feature and evaluate its effectiveness on astrophysical problems requiring the processing of large datasets simultaneously, such as the study of the entire emission of the Galaxy. We used these algorithms to solve the large sparse systems arising from SPI data processing and to obtain both their solutions and the associated variances. In conclusion, thanks to these newly developed tools, processing large datasets arising from SPI is now feasible with both a reasonable execution time and a low memory usage.

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The INTEGRAL spacecraft – in-orbit performance

Cited by 69 publications

References 3 publications

The INTEGRAL mission

The INTEGRAL mission

Variability and Spectral Modeling of the Hard X-Ray Emission of Gx 339–4 in a Bright Low/Hard State

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