Since the launch of INTEGRAL in 2002, ISDC Newsletters usually mark the release of new versions of the INTEGRAL Off-line Scientific Analysis (OSA) package. The present issue follows this tradition by announcing the release of OSA 10, coinciding with the 10 years of INTEGRAL to be celebrated at a conference in Paris next month. The Newsletter is presented in a new layout since 2010 to reflect the new nature of the ISDC as a multi-mission data centre for astrophysics.
The HEAVENS interface — which started with the idea to provide high-level INTEGRAL scientific products to the community — now incorporates also spectra, images, or lightcurves of Planck, RXTE, Fermi, and HEGRA data; and more is to come.
In parallel, the ISDC diversified its activities with the participation to hardware developments for the Japanese ASTRO-H mission and the POLAR experiment to measure gamma-ray burst polarization. The first light of the FACT telescope reflects the activity of the institute in Cherenkov astronomy at TeV energies. ISDC is also strongly involved in ESA's upcoming Gaia mission and collaborates on international projects like LOFT, JEM-EUSO, and SPICA/SAFARI.
An overview of improvements in OSA 10: The upper plots show the stable IBIS-ISGRI energy calibration through-out the mission lifetime and the lower images illustrate JEM-X improvements for imaging.
The INTEGRAL Off-line Scientific Analysis (OSA) software package provides tools to analyse data from the four INTEGRAL instruments — IBIS, SPI, JEM-X and OMC — and some generic tools.
OSA version 10.0 provides crucial improvements of the IBIS/ISGRI energy calibration software and new features for the JEM-X imaging.
OSA 10 runs on Linux and recent Mac OS X platforms and is provided in binary and source format, together with documentation, calibration files and catalogues.
The user can download and install the OSA 10 software from the download page and run it with the help of the fully revised documentation. Good luck with your analysis!
The reconstruction of the incoming photon energy on the IBIS/ISGRI detector is achieved by measuring the electronic pulse height and its rise time, and converting then these values to keV in three steps: correction of the secular drift, equalization of the pixels to a standard response, and correction of the pulse height vs rise time non linear degeneracy. The first two steps assume a linear relation between the pulse height and the reconstructed energy, and therefore two parameters are used: a gain and an off-set.
IBIS-ISGRI energy calibration inprovement from OSA 9 to OSA 10 showing the mean energy (top) and width (bottom) of two background lines. On the left for tungsten (W at 59 keV) and on the right for sodium (22Na at 511 keV).
As detailed in the ISGRI energy calibration document prepared by the IBIS instrument team, the ISGRI spectral gain has been observed to decrease with time. In OSA9, the description of the gain drift was based on IREM counters integrated over time, to take into account the solar flares, but the measurement of the background lines at 59 and 511 keV showed that this correction was not valid along the whole mission, as shown in the figure (black diamonds).
OSA 10 improves very significantly the reconstruction of the photon energy, in particular the secular drift of gains, which was not correctly accounted for in OSA 9. The main improvements are the following:
JEM-X mosaic images comparison with OSA 9 (left) and the new PIF method of OSA 10 (right). The images are centered on the bright binary GRS 1915+105. The new PIF method removes many background structures that prevented the detection of fainter sources.
The software has been significantly improved in several aspects.
The improvements to the standard spectral extraction algorithm increase noticeably the stability of almost-constant source spectra throughout the mission and refine the determination of source detection significance at the imaging level.
The introduction of an novel algorithm for the image reconstruction, based on the Pixel Illumination Fraction (PIF), leads to substantial improvements on the sensitivity for weak source detection, in particular in crowded fields or in vicinity of bright sources.
The reconstruction of energy is based on continuously updated calibration files which are ingested in the instrument characteristic repository maintained by ISDC.
JEM-X mosaic image of the Galactic Plane Scan (GPS) observations of revolution 399 in the 3-10 keV band processed and displayed in an Aitoff-Hammer projection.
In the production of JEM-X mosaic maps, the user has now the possibility to choose the Aitoff-Hammer projection for mosaicking large fractions of the sky.
Finally, the JEM-X User Manual has been thoroughly updated.
The SPI software has been remarkably stable over the past years, so the main improvements are related to updated calibration files:
In addition, the pipeline scripts have been corrected for marginal bugs in the parameter handling.
"HEAVENS becomes international": illustrated here by the scupture of star constellations in the garden of the United Nations in Geneva.
The HEAVENS interface provides on-the fly analysis services for a number of instruments. These services are designed to produce straightforwardly high-level scientific products for any sky position, time and energy intervals without requiring mission specific software or detailed instrument knowledge.
INTEGRAL products are already available since many months. The services are now extended to include on-the-fly analysis of data from the Spectrometer SPI. This will be further enhanced in the next months with PICSIT all sky products and high-resolution lightcurves for the ISGRI an JEM-X instruments.
HEAVENS becomes truly multi-mission and international with the addition of RXTE/PCA and ASM products (in collaboration with the University of Erlangen-Nuremberg and NASA GSFC) and Fermi-LAT. The Fermi-LAT services will soon become more flexible and new instruments will become available in collaboration with University of Leicester and the FACT collaboration.
HEAVENS uses a client-server architecture, similar to that used by the Virtual Observatory but with extended query possibilities to allow on-the-fly generation of products matching the user needs. The HEAVENS interface can be installed on any web site and is regularly enhanced to include interfaces to existing analysis packages.
The HEAVENS interface is visited more than 300 times per month on average and we are looking forward to obtaining reactions of users to the new services offered.
RXTE/PCA lightcurve of the giant binary star Eta Carinae (in the 2-10 keV energy range) as provided by the HEAVENS interface. The entire lightcurve is displayed to the right, in which the 5.5 yr period of this binary system can be identified. The left panel shows a zoom on the X-ray maximum and minimum that occurred in 2003. At the bottom, a number of plotting options can be interactively changed; links to download the data in the ASCII and FITS formats are also available.
The data obtained by the PCA instrument on-board the Rossi X-ray Timing Satellite (RXTE) satellite over the entire mission lifetime (December 1995 — January 2012) are now available in HEAVENS.
After specifying a source name or a sky position, users may immediately retrieve the following publication-grade data products that are generated on-the-fly from pre-processed data:
Additionally, users may choose which of the five proportional counter units (PCUs) shall be included in the products, and whether to use only the top or all layers.
Currently, all the so-called RXTE/PCA standard2f data have been integrated into the HEAVENS interface: this provides lightcurves with a shortest timebin of 16 seconds, as well as spectra, for all observations. Other modes, offering higher time resolution, are expected to be included in the future. The new Python script used to process all observations will be made freely available from the HEAVENS web page.
The All Sky Monitor (ASM) on-board RXTE, is composed of three three wide-angle shadow camera equipped with Xenon proportional counters, producing almost continuous lightcurve with measurement every few hours in 3 energy bands. The data, that were processed by the ASM team at HEASARC and MIT, are now available through the HEAVENS interface as well.
Credits: The RXTE/PCA pipeline for HEAVENS has been developed by Jean-Christophe Leyder based on earlier data analysis scripts provided by Jörn Wilms.
A daily-binned light curve of the Crab Nebula in the 0.1-100 GeV range as provided by the HEAVENS interface. It shows the two unexpected gamma-ray flares of September 2010 and April 2011.
The HEAVENS interface provides Fermi-LAT light curves, with both daily and weekly binning, for all the sources in the Second Fermi-LAT Catalog, from the beginning of the Fermi mission to the latest FSSC public data release. These data are precomputed products.
The light curves are produced using the likelihood analysis method, and a complex algorithm for the detection and the sky-model building. The sky is partitioned in about 300 regions, and independent likelihood analysis is performed for each of them, both on daily and weekly time-scales. Besides fluxes, the pipeline provides detection significance, spectral index, and energy fluxes. The count maps, are generated on the fly, for the integration period corresponding to the light-curve extraction interval.
Credits: The Fermi-LAT pipeline for HEAVENS has been developed by Andrea Tramacere using the latest version of the Fermi Science Tools (v9r27p1).
So far, the HEAVENS interface for the Spectrometer on INTEGRAL (SPI) was limited to spectra for only about 25 sources — brighter than 20 mCrab — listed in Bouchet et al. (2008). These spectra were obtained off-line by using the "spimodfit" analysis tools included in OSA 9, and did not permit the user to select specific time and/or energy intervals for a given source of interest.
A new procedure is available now in HEAVENS for the on-the-fly analysis of SPI data included in the public INTEGRAL data archive maintained at ISDC. Sky images, light-curves and spectra can be obtained for any source detected by the INTEGRAL spectrometer and time interval. In this first release of the on-line analysis of SPI data you can get:
Please note that the SPI on-line tools included in HEAVENS provide a robust first-look analysis of SPI data. A similar on-line analysis tool but with more options regarding source variability and energy/time binning is the SPI Data Analysis Interface (DAI), which will soon be provided by the SPI Team in Toulouse. Both these analysis tools are intended for an easy and fast approach to the SPI capabilities. A wider set of analysis configurations is provided by the OSA software delivered at ISDC.
IBIS/ISGRI high-resolution lightcurve of Vela X-1 in time bins of ~10 sec from the HEAVENS interface.
Source lightcurves are available in HEAVENS for several instruments of INTEGRAL down to the resolution of the dithering pointing (typically 2000 sec). High-time resolution lightcurves in broad energy bands will be included in the near future for the soft gamma-ray imager IBIS/ISGRI. The maximum time resolution is adapted to the source significance in each pointing and allows to obtain meaningful results down to timescales of 10 sec on Vela X-1 or of sub-seconds on gamma-ray bursts in the field of view.
Planck spectra in the radio-to-submillimeter range are provided via HEAVENS since spring 2011. They are based on the Early Release Compact Source Catalog (ERCSC; Planck Collaboration 2011, A&A 536, A7) that has been made publicly available on 11 January 2011. The advantage of HEAVENS is to provide spectra of positionally coincident sources constructed by combining the fluxes from the nine distinct frequency catalogs of the ERCSC.
The ERCSC is a list of high reliability (>90%) compact sources observed by Planck during its first whole sky coverage, between 13 August 2009 and 6 June 2010. It includes more than 15'000 Galactic and extragalactic sources, from cold cores and HII clouds in star forming regions to blazars and high-redshift quasars.
Future plans for HEAVENS are the inclusion of the Planck nominal mission results that should be released in early 2013. Besides updated spectra from the Planck Catalogue of Compact Sources (PCCS), we foresee to also provide sky images for a user-defined position on the sky. This will be possible for any of the nine frequencies probed by Planck — between 30 GHz and 857 GHz — and possibly also for component separated maps for dust, free-free and synchrotron emission of the Galaxy.
Picture of the Filter Wheel Mechanics Qualification Model for the Soft X-ray Spectrometer (SXS) instrument aboard ASTRO-H.
ASTRO-H is an international X-ray observatory mission led by the Japan Aerospace Exploration Agency (JAXA), in collaboration with NASA, ESA and several European countries. In particular, the Netherlands and Switzerland are contributing hardware for the scientific payload. ASTRO-H will be launched in 2014. ASTRO-H will combine sensitive wide energy coverage from 0.3 to 600 keV, thanks to its soft X-ray and hard X-ray telescopes and a Compton camera instrument. In addition, it will provide for the first time spatially resolved spectroscopy with exceptional spectral resolution thanks to its Soft X-ray Spectrometer (SXS) instrument, a cryogenic calorimeter.
Picture of the Filter Wheel Electronics Engineering Model for the SXS instrument aboard ASTRO-H.
ISDC, University of Geneva, participates in the ASTRO-H mission in collaboration with SRON (NL) by developing a filter wheel and calibration system for the SXS. The filter wheel is equipped with active X-ray sources to monitor the evolution of the SXS energy calibration during the observation. Production of the flight hardware has started in Swiss industries.
The ESSC is part of a European synergy between ESA and the ISDC. The main goal is to ensure the availability of the required expertise in ASTRO-H and its instruments for the European astronomical community. An essential part of the ESSC will therefore be to provide technical support to European observers, in particular in the form of a help desk. While the European AO process will be led by ESA, the ESSC will contribute by providing technical support to proposers and the time allocation committee. The ESSC will also organize data analysis workshops dedicated to ASTRO-H. Within the ASTRO-H team, the ESSC tasks also include participation in the user documentation, software testing and calibration analysis.
The ESSC will be actively promoting ASTRO-H, for instance through scientific conferences, like the European Week for Astronomy and Space Science 2012, where a Special Session has been organized.
More details are available on the ASTRO-H website at the ISDC.
The FACT Cherenkov Telescope at La Palma, Canary Islands, is made of a refurbished HEGRA mount, new mirrors and the new-technology, silicon-based camera.
Some events detected by the Camera during the first nights of observations. Ellipsis, patches and circles are the signature of gamma-ray photons, cosmic-rays and muons, respectively.
The First G-APD Cherenkov Telescope (FACT) is the first imaging atmospheric Cherenkov telescope using Geiger-mode avalanche photodiods (G-APDs) as photo sensors. This rather small, low-cost telescope does not only serve as a test bench for this technology in Cherenkov astronomy, but also monitor bright sources (in particular active galactic nuclei) in the TeV energy range. FACT is installed at the Roque de los Muchachos observatory on the island of La Palma and build an operated by scientists from ETHZ, EPFL and the University of Geneva in Switzerland and the universities of Dortmund and Würzburg in Germany.
A portion of the lightcurve of the Crab nebula showing the background subtracted event rate.
The first light of FACT occurred in October 2011 and since then it generated about 64TB of data. The data from the G-APD camera are of excellent quality. Calibration is still on-going but meaningful scientific results were already obtained on blazar flares. Gaining more experience with these new detectors is very important. Following on the FACT success, they are now considered for the future Cherenkov Telescope Array (CTA). The data from FACT are stored in FITS format and are used to prototype the CTA data acquisition and analysis chain.
POLAR modulation curves — distributions of the Compton scattering angle χ — for two test runs conducted at the European Synchrotron Radiation Facility (ESRF) on November 2011, for an incoming photon energy of 356 keV. The polarized data has been corrected by subtracting unpolarized data. This allows to significantly reduce the systematic effects, e.g. induced by the geometry.
POLAR is a novel compact space-borne Compton polarimeter conceived for a precise measurement of hard X-ray polarization and optimized for the detection of the prompt emission of Gamma-Ray Bursts (GRB) in the energy range 50-500 keV. A first detailed measurement of the polarization from astrophysical sources will lead to a better understanding of the source geometry and of the emission mechanisms. Thanks to its large modulation factor, effective area, and field of view (1/3 of the visible sky), POLAR will be able to reach a minimum detectable polarization (1-σ level) of about 3% for several GRB measurements per year.
POLAR consists of 1600 low-Z plastic scintillator bars, read out by 25 flat-panel multi-anode photomultipliers. The incoming photons undergo Compton scattering in the bars and produce a modulation pattern. Simulations and experiments have shown that the polarization degree and angle can be retrieved from this pattern with the accuracy necessary for pinning down the GRB mechanisms.
Two full-scale engineering models are currently under construction in Europe, to undergo calibration and space qualification campaigns in the end of 2012. The flight model will be placed onboard the Chinese spacelab TG-2, scheduled for launch in low Earth orbit in 2014.
Gaia Deployable Sunshield Assembly (DSA) fully deployed at Astrium Toulouse. Credit: Astrium France
Gaia is a pioneering ESA astronomy mission set to revolutionise our view of the Galaxy with a precise, detailed stereoscopic survey of the billion brightest celestial objects. The development phase is well advanced and the launch is currently planned for end 2013. The first Operational Rehearsal was conducted between 25th June and 4th of July this year. The payload module (including the Radial Velocity Spectrometer and the Basic Angle Monitor) is now integrated and ready for testing (see ESA's press release). Stages 1 and 2 of the end-to-end tests were successfully completed and stage 3 is on-going.
In the Gaia project, the Geneva University group leads the Variability Processing and Analysis Coordination Unit, called CU7. In addition the ISDC hosts the associated Data Processing Center (DPCG). Our main objectives are to analyze time series measurements in order to characterize and classify variable sources and to prepare the Gaia intermediate and final catalogue releases. For each variable source, we will provide information such as variability amplitude, period (if any), model-fitting parameters (e.g. Fourier series coefficients) and variability type (Cepheid, Eclipsing binary, etc).
One specific challenge is to exploit the various types of Gaia measurements, astrometric, photometric, spectro-photometric and those provided by the radial-velocity spectrometer, within the multi-epoch nature of the mission.
Our group of 16 people (10 FTEs plus PhD students, post-docs and scientific support) contributes to Gaia in several ways:
Geneva also contributes to CU6 in the multiple transits analysis work package and to CU2 with models of variable objects implemented in the Universe Model.
More information is available on the Gaia website at the ISDC and in the Gaia DPAC newsletters.
LOFT, the Large Observatory For X-ray Timing, is a new space project devoted to observations of the X-ray sky with an unprecedented timing and spectral resolution. It was selected by ESA on February 2011 as one of the four space missions concepts of the Cosmic Vision programme that will compete for a launch opportunity at the start of the 2020s.
The two instruments on-board LOFT, the Large Area Detector (LAD) and the Wide Field Monitor (WFM), make use of newly developed large area monolithic silicon drift detectors. These components require modest resources and operation complexity, and permitted to develop a realistic concept for a very large effective area mission (~10 square meters) endowed with a fine spectral resolution of <260 eV FWHM over a broad energy band (2-80 keV). These characteristics make LOFT specifically designed to exploit the diagnostics of very rapid X-ray flux and spectral variability to investigate with unprecedented details the motion of matter down to distances very close to neutron stars and black holes. The observations performed with the LAD and the WFM on-board LOFT will primarily aim at clarifying the properties of matter under extreme conditions, one of the central theme of the ESA Cosmic Vision program.
Geneva has been contributing to the mission design since the very early beginning of the project conception in 2010. The currently on-going assessment phase of LOFT will terminate at the end of 2013, when a further down-selection of the four M3 mission candidates is expected.
Please check the LOFT web site for additional information.
SPICA (Space Infrared Telescope for Cosmology and Astrophysics) is a project led by the Japan Aerospace Exploration Agency (JAXA), in collaboration with ESA and European countries, Korea, and Taiwan, to be launched in 2022. With a 3-meter diameter, its large mirror will be actively cooled down to less than 6K. SPICA will achieve high sensitivity and spatial resolution. Four instruments are currently planned in the payload:
The infrared emission of SPICA's cryogenically-cooled telescope will be reduced significantly, virtually providing no contribution in the wavelength coverage of SPICA. Astronomical diffuse emission and confusion will be the only limiting background.
ISDC is a member of the European Consortium to build and operate the SAFARI instrument onboard the SPICA mission. ISDC leads the development and operation of the Instrument Control Center for SAFARI, in close collaboration with the PI institute (SRON, Groningen), the international consortium members involved in SAFARI, ESA, and JAXA.
The Extreme Universe Space Observatory on board of the Japanese Experiment Module of the ISS (JEM-EUSO) will be a space-based detector of Ultra-High-Energy Cosmic Rays (UHECR). The project is developed by an international collaboration led by JAXA and RIKEN in Japan, with strong European participation. JEM-EUSO is a part of the ESA's ELIPS (European Program for Life and Physical Sciences) program for experiments at the ISS.
JEM-EUSO will detect flashes of ultraviolet fluorescence emission excited along the tracks of UHECR induced high-energy particle showers in the Earth atmosphere. To detect the short (100 millisecond long) flashes of fluorescence light from extremely rare UHECR events (about one 1 event per 100 square kilometers per year), JEM-EUSO will monitor from space a 400 km x 400 km region on the surface of the Earth using a 2.5 m diameter refractor telescope sensitive in the 300-400 nm wavelength range. The focal surface of JEM-EUSO telescope will be equipped with multi-anode photomultiplier tubes with an overall 200 thouthand pixels providing images of the Earth atmosphere in the 60 degree field of view with angular resolution 0.1 degree and time resolution 2.5 microsecond.
JEM-EUSO will use the Earth atmosphere as a giant detector of high-energy particles. Proper interpretation of the cosmic ray data provided by JEM-EUSO will require precise knowledge of the state of this natural high-energy particle detector. To this end, JEM-EUSO will be equipped with a dedicated atmospheric monitoring system consisting of a LIght Detection And Ranging (LIDAR) device and and an infrared camera.
Switzerland is invovled in JEM-EUSO collaboration, with responsibilities in the Atmospheric Monitoring System (development of the LIDAR) and in the set-up of JEM-EUSO Science Data Centre. Swiss institutes invovled in JEM-EUSO are University of Geneva, ETH Zurich and CSEM Neuchatel.
ISDC will host a joint meeting on the Atmospheric Monitoring and Simulations working groups of JEM-EUSO collaboration on October 17-19, 2012.
Information on the meeting can be found on the JEM-EUSO website of the ISDC.
The 9th INTEGRAL workshop "An INTEGRAL view of the high-energy sky (the first 10 years)" will take place from 15 to 19 October 2012 in Paris, Bibliothèque Nationale de France (Bibliothèque François Mitterrand). The workshop will be sponsored by ESA, CNES and other French and European Institutions.
During this week, and in particular on 17 October 2012, we will celebrate the 10th anniversary of the launch of the INTEGRAL mission.
The main goal of this workshop is to present and to discuss (via invited and contributed talks and posters) latest results obtained in the field of high-energy astrophysics using the International Gamma-Ray Astrophysics Laboratory INTEGRAL, as well as results from observations from other ground- and space-based high-energy observatories and from associated multi-wavelength campaigns.
More details are available on the conference website.
The "Physics at the Magnetospheric Boundary" conference is aimed at bringing together specialists working theoretically, numerically and observationally on processes occurring at the limit of the magnetically dominated region around accreting objects such as neutron stars, white dwarfs, and T Tauri stars, where the surrounding hot plasma is finally captured.
Different manifestations of similar physical processes occur in this wide variety of celestial sources and have been investigated since the 1960s by different scientific communities. The conference represents a precious opportunity of exchange between research groups working on the topic of accretion, across different wavelengths and source types. It poses the basis for the next steps forward in our understanding of the physics at the magnetospheric boundary.
Planned sessions for this conference include:
More details are available on the conference website.
