| No. 10 - July 12, 2002 | Edited by Thierry Montmerle & Marc Türler |
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| INTEGRAL is (almost) fit for service ! |
This relatively short Newsletter reports perhaps the most important news about
INTEGRAL so far : it is being ``unplugged'' and dismantled from the ESTEC
facility, to be shipped to Baikonur. A final, formal ESA acceptance review will
take place next week, putting an end to months of successful, rigorous tests of
the whole satellite, described in preceding Newsletters. And now ? Have
a look at the INTEGRAL News to learn what is going to happen
in the next few months, until the launch date of October 17th !
The image on the right shows INTEGRAL in the Large Space Simulator (LSS) at ESTEC for testing its thermal resistance to the extreme conditions in space. For additional information see ESA's PR page.
So after such a nice job has been done, and since the holiday season is here, time to go to the beach ? Not quite ! The hardware part is done, but the software development continues, both within the Instrument Teams and at the ISDC. The INTEGRAL Burst Alert System (IBAS) is being released and the Archive (which, of course, still contains only data from tests) is already available on-line.
The clock has started ticking for good. In less than 100 days INTEGRAL should be in space!
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| Overview of Activities |
| Roland Walter (ISDC Geneva) |
The configuration of the ISDC is being finalized for launch. The operational hardware is now in place and the software needed for the technical processing of the INTEGRAL data is being frozzen.
The archive is on-line and is being filled with the data necessary for the processing. The payload calibration data have been processed and ingested in the archive as well.
The ISDC is also preparing some software releases. A first release of the IBAS gamma-ray burst alert client software has just occured and a pre-release of the offline analysis software to selected users is being prepared for the end of this month. This software is tested on both linux and Solaris.
Testing the software is still a major task, this is occuring in frame of end-to end tests (see below) and in various technical and scientific validation activities.
The status of the ground segment and of the instruments has been reviewed very
recently by ESA with good results. The Flight Acceptance Review is now taking
place and the INTEGRAL mission should be declared ready for the launch in a few
days.
The launch is planned on October 17th at 04:41 UTC. The first telemetry packet should arrive at ISDC about 1hr later.
The image on the right shows the transport of a Russian PROTON rocket to its launch site at the Cosmodrome of Baikonur, Kazakhstan.
For the first time the complete system was run in realistic PV operational conditions, including the archive and the scientific analysis. SPI, IBIS, JEM-X and IREM instrument team members used the interactive software to monitor their instruments. The OMC team used that software remotely from Madrid.
Both the near real time data and consolidated TM generated during a previous test were processed simultaneously. The technical processing occured very smoothly and almost nominally. The gamma-ray burst detection system (IBAS) ran all the time but did not detected any burst (as expected). Sky images were built interactively from ISGRI, SPI and JEM-X data.
Data generated from the consolidated TM was archived. Standard analysis was run on some ``dummy'' observations. Archive browse is working. Even if data distribution has not yet been used in its full scope, ftp and DVD distribution were performed.
Several operational meetings took place to exercice people in their operational roles.
| First Release of the INTEGRAL Burst Alert System (IBAS) |
| Sandro Mereghetti (IASF Milano) |
INTEGRAL is expected to detect and localize about one gamma-ray burst (GRB) per month and to distribute the derived GRB coordinates in near real time with an accuracy of a few arcminutes. Users interested in obtaining the GRB positions with the shortest time delay (e.g., for a robotic telescope) can now subscribe to the distribution list and download the Client Software required to receive the IBAS Alert Packets. More information and detailed instructions can be found here.
| The INTEGRAL Archive and Data Distribution |
| Roland Walter (ISDC Geneva) |
The operational archive is being filled with basic auxiliary files and a first version of instrument characteristic files (calibration and responses).
During operations, auxiliary files, raw and prepared data resulting from the technical processing of the consolidated telemetry will be made available in the archive with a delay of 20 days. The first standard analysis products will be made available and distributed starting in March 2003 when the Performance Validation program and the calibration observation of the Crab will be performed.
The satellite was in a flight configuration excepting that for most of the time the IBIS data were channelled through a Fast Acquisition System (FAS) that allows a higher data collection rate from IBIS. High energy instruments were in the standard in-flight operational modes (photon by photon for SPI and IBIS, JEM-X in data taking), OMC was off.
The calibration was performed using different radioactive sources (main lines from 60 keV to 2754 keV) on different positions (on axis and off axis beams). An X-ray generator was also used either in direct mode or in fluorescence mode. This device was also used on January 24th (between 00:00 and 01:30) to simulate a Gamma Ray Burst.
From these two weeks of data, the ISDC analysis software created 410 science windows data sets. Each calibration run was dedicated to a specific test and lasted from 3 minutes to 8 hours. The longest runs were split into several science windows.
All the data (including the IBIS FAS data) are now archived in a format identical to the format used for flight data. The science data are not publicly accessible.
For short observations (duration up to about one revolution, i.e., 3 days) the data will be shipped through the network (ftp distribution) or on DVDs according to the preference set in the proposal.
For longer observations our baseline will be to ship the data on LTO tapes. In those cases the PI of the observation will first be contacted by e-mail. Distribution of DVD and tapes will occur through normal (snail) mail.
Distribution through the network is a good approach for short observations for all observers who are well connected to the pan-european Gbit research network GEANT.
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| INTEGRAL Gets Ready for Launch |
| Raffaello Carli & Philippe Sivac (ESTEC) |
INTEGRAL's preparations for launch with a Russian PROTON rocket from Baikonur are now in their final phases.
The satellite is demated. The payload and the service modules are currently being packed in
separate containers. The Alenia team will then finalize the removal and packing of all the ground equipment into sea
containers, to be ready for the first Antonov flight scheduled to arrive in
Baikonur on the 17th of August. The spacecraft modules will arrive one week
later by a second flight and the final integration in Baikonur will start.
The image on the left is one of the last picture of INTEGRAL before it was demated. It shows the AIV (Assembly, Integration and Verification) Team in front of the spacecraft in the clean room of ESTEC at Noordwijk (Netherlands).
The image on the right shows an Antonov aircraft. Two flights of those heavy load carrier will be needed to transport INTEGRAL to Baikonur in Kazakhstan, Russia.
The satellite should be mated again by September 1st and the Abbreviated Functional Test (AFT) should be completed by mid-September. This test consists in checking the spacecraft status by performing short essential tests of the instruments and the sub-systems. After filling with hydrazine fuel at the end of September, the satellite should be ready to be mated on the launcher in early October. The official launch date is still fixed to October 17th, 2002.
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| The origin of the young stellar population in the solar neigborhood - a link to the formation of the Local Bubble? | |
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T. W. Berghöfer1, D. Breitschwerdt2 1. DESY Hamburg, Notkestr. 85, 22607 Hamburg, Germany 2. Max-Planck-Institut für Extraterrestrische Physik, Giessenbachstr. 1, 85741 Garching, Germany | |
| Accepted for publication in A&A on April 19, 2002 | |
| Abstract. We have analyzed the trajectories of moving stellar groups in the solar neighborhood in an attempt to estimate the number of supernova explosions in our local environment during the past 20 million years. Using Hipparcos stellar distances and the results of kinematical analyses by Asiain et al. (1999a) on the Pleiades moving groups, we are able to show that subgroup B1, consisting of early type B stars up to 10 solar masses, but lacking more massive objects, has passed through the local interstellar medium within less than 100 pc. Comparing the stellar content of B1 with the initial mass function derived from the analysis of galactic OB associations, we estimate the number of supernova explosions and find that about 20 supernovae must have occurred during the past 10 - 20 million years, which is suggested to be the age of the Local Bubble; the age of the star cluster is about 20 - 30 million years. For the first time, this provides strong evidence that the Local Bubble must have been created and shaped bymulti-supernova explosions and presumably been reheated more than 1 million years ago, consistent with recent findings of an excess of 60Fe in a deep ocean ferromanganese crust. Calculating similarity solutions of an expanding superbubble for time-dependent energy input, we show that the number of explosions is sufficient to explain the size of the Local Bubble. The present energy input rate is about dESN /dt ~ 5 1036 erg/s, in good agreement with the estimated local soft X-ray photon output rate. It seems plausible that the origin of the Local Bubble is also linked to the formation of the Gould Belt, which originated about 30-60 Myrs ago. | |
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E-mail contact | Preprint access |
| Degradation and recovery of Ge detectors:tests prior to a space mission | |
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F. Albernhe1,2,V. Borrel1,2,P. Frabel2,G.
Vedrenne2,R. Coszach3, et al. 1. IUT,Univ. Paul Sabatier,Toulouse,France 2. CESR,Univ. Paul Sabatier,Toulouse,France 3. IPN,Univ.Cath.Louvain,Louvain-la-Neuve,Belgium | |
| Accepted for publication in NIM A on June 18,2002 | |
| Abstract. Ge detectors onboard the future INTEGRAL mission of ESA will be deteriorated by secundary neutrons.In the present work,flight model Ge detectors were degraded by accelerator-produced neutrons,and then annealed.The detector recovery was found very sensitive to the annealing temperature.Transients following a high-voltage cut-off were studied as well. | |
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E-mail contact | |
| Discovery of absorption features in the X-ray spectrum of an isolated neutron star | |
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D. Sanwal1, G.G. Pavlov1, V.E. Zavlin2 & M.A.
Teter1 1. Pennsylvania State University, 525 Davey Lab, PA 16802, USA 2. MPE, Giessenbachstr., 85748 Garching, Germany | |
| Accepted for publication in ApJ Letters on June 17, 2002 | |
| Abstract. We observed 1E 1207.4-5209, a neutron star in the center of the supernova remnant PKS 1209-51/52, with the ACIS detector aboard the Chandra X-ray observatory and detected two absorption features in the source spectrum. The features are centered near 0.7 keV and 1.4 keV, their equivalent widths are about 0.1 keV. We discuss various possible interpretations of the absorption features and exclude some of them. A likely interpretation is that the features are associated with atomic transitions of once-ionized helium in the neutron star atmosphere with a strong magnetic field. The first clear detection of absorption features in the spectrum of an isolated neutron star provides an opportunity to measure the mass-to-radius ratio and constrain the equation of state of the superdense matter. | |
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E-mail contact | Preprint access |
| XMM-Newton observations of ultraluminous X-ray sources in nearby galaxies | |
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L. Foschini1, G. Di Cocco1, L. C. Ho2, L.
Bassani1, M. Cappi1, et al. 1. Istituto di Astrofisica Spaziale e Fisica Cosmica (IASF-CNR) - Sezione di Bologna (Formerly iTeSRE), Via Gobetti 101, I-40129, Bologna (Italy) 2. The Observatories of the Carnegie Institution of Washington, 813 Santa Barbara Street, Pasadena, CA 91101 (USA) | |
| Accepted for publication in A&A on June 24, 2002 | |
| Abstract. An XMM-Newton study of ultraluminous X-ray sources (ULX) has been performed in a sample of 10 nearby Seyfert galaxies. Eighteen ULX have been found with positional uncertainty of about 4". The large collecting area of XMM-Newton makes the statistics sufficient to perform spectral fitting with simple models in 8 cases. The main results of the present minisurvey strengthen the theory that the ULX could be accreting black holes in hard or soft state. In some cases, the contribution of the ULX to the overall X-ray flux appears to be dominant with respect to that of the active nucleus. In addition, 6 ULX present probable counterparts at other wavelengths (optical/infrared, radio). A multiwavelength observing strategy is required to better assess the nature of these sources. | |
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E-mail contact | Preprint access |
| IBIS/PICsIT Data and Analysis | |
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J.B. Stephen, L. Foschini, F. Gianotti, E. Caroli, G. Malaguti, et al. Istituto di Astrofisica Spaziale e Fisica Cosmica (IASF) del CNR, Sezione di Bologna (formerly iTeSRE). Via Gobetti 101, 40129 Bologna (Italy) | |
| Accepted for publication in Proceedings of the 22nd Moriond Astrophysics Meeting - The Gamma-ray Universe (Les Arcs, France, 9-16 March 2002) on May 3, 2002 | |
| Abstract. The imager IBIS on board INTEGRAL is composed of two detector planes: ISGRI (15 keV - 1 MeV) and PICsIT (170 keV - 10 MeV). Here we describe the data structure of PICsIT and the instrument specific software, including the standard scientific analysis. Some examples of shadowgrams and spectra are shown, by using data collected during the End-to-End Tests of January 2002. | |
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E-mail contact | Preprint access |
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