The XMM-Newton observatory, launched by the European Space Agency in 1999, is still one of the scientific community’s most important high-energy astrophysics missions. After almost 15 years in orbit its instruments continue to operate smoothly with a performance close to the immediate post-launch status. The competition for the observing time remains very high with ESA reporting a very healthy over-subscription factor. Due to the efficient use of spacecraft consumables XMM-Newton could potentially be operated into the next decade. However, since the mission was originally planned for 10 years, progressive ageing and/or failures of the on-board instrumentation can be expected. Dealing with them could require substantial changes of the on-board operating software, and of the command and telemetry database, which could potentially have unforeseen consequences for the on-board equipment. In order to avoid this risk, it is essential to test these changes on ground, before their upload. To this aim, two flight-spare cameras of the EPIC experiment (one MOS and one PN) are available on-ground. Originally they were operated through an Electrical Ground Support Equipment (EGSE) system which was developed over 15 years ago to support the test campaigns up to the launch. The EGSE used a specialized command language running on now obsolete workstations. ESA and the EPIC Consortium, therefore, decided to replace it with new equipment in order to fully reproduce on-ground the on-board configuration and to operate the cameras with SCOS2000, the same Mission Control System used by ESA to control the spacecraft. This was a demanding task, since it required both the recovery of the detailed knowledge of the original EGSE and the adjustment of SCOS for this special use. Recently this work has been completed by replacing the EGSE of one of the two cameras, which is now ready to be used by ESA. Here we describe the scope and purpose of this activity, the problems faced during its execution, the adopted solutions, and the tests performed to demonstrate the effectiveness of the new EGSE.
After more than twelve years in orbit and two years beyond the design lifetime, XMM-Newton continues its near
faultless operations providing the worldwide astronomical community with an unprecedented combination of imaging
and spectroscopic X-ray capabilities together with simultaneous optical and ultra-violet monitoring. The interest from the
scientific community in observing with XMM-Newton remains extremely high with the last annual Announcement of
Observing Opportunity (AO-11) attracting proposals requesting 6.7 times more observing time than was available.
Following recovery from a communications problem in 2008, all elements of the mission are stable and largely trouble
free. The operational lifetime if currently limited by the amount of available hydrazine fuel. XMM-Newton normally
uses reaction wheels for attitude control and fuel is only used when offsetting reaction wheel speed away from limiting
values and for emergency Sun acquisition following an anomaly. Currently, the hydrazine is predicted to last until
around 2020. However, ESA is investigating the possibility of making changes to the operations concept and the onboard
software that would enable lower fuel consumption. This could allow operations to well beyond 2026.
On December 10th 2004 the XMM-Newton observatory celebrated its 5th year in orbit. Since the beginning of the mission steady health and contamination monitoring has been performed by the XMM-Newton SOC and the instrument teams. Main targets of the monitoring, using scientific data for all instruments on board, are the behaviour of the Charge Transfer Efficiency, the gain, the effective area and the bad, hot and noisy pixels. The monitoring is performed by combination of calibration observations using internal radioactive calibration sources with observations of astronomical targets. In addition a set of housekeeping parameters is continuously monitored reflecting the health situation of the instruments from an engineering point of view. We show trend behaviour over the 5 years especially in combination with events like solar flares and other events affecting the performance of the instruments.
The X-ray observatory XMM-Newton is now in orbit for more than 5 years. The performance of the EPIC-pn CCD camera has been monitored since and its calibration has been improved steadily. We report in this presentation on our recent investigations in different calibration issues: Data of the on-board Fe-55 calibration source were used for monitoring the charge transfer efficiency (CTE) degradation. A special calibration observation of the line-rich supernova remnant Cas-A in the extended Full Frame Mode was used to refine the energy calibration in this mode. Together with ground measurements, a non-routine observation of the calibration target N132D will lead to an improvement of the CTE correction of the Large Window Mode.
Various X-ray satellites have used the Crab as a standard candle to perform their calibrations in the past. The calibration of XMM-Newton, however, is independent of the Crab nebula, because this object has not been used to adjust spectral calibration issues. In 2004 a number of special observations were performed to measure the spectral parameters and the absolute flux of the Crab with XMM-Newton's EPIC-pn CCD camera. We describe the results of the campaign in detail and compare them with data of four current missions (Integral, Swift, Chandra, RXTE) and numerous previous missions (ROSAT, EXOSAT, Beppo-SAX, ASCA, Ginga, Einstein, Mir-HEXE).
The large collecting area of XMM-Newton combined with the good energy resolution of the EPIC-pn CCDs allows the study, with unprecedented detail, of accretion processes onto neutron stars and black holes. The EPIC-pn CCD camera in Timing mode, in which data are read out continuously, is among the fastest X-ray CCD camera available; however, telemetry constraints do not allow full use of these capabilities for many sources because currently randomly distributed data gaps are introduced by the on-board data handling electronics. As an alternative, we have proposed to implement a modification of the Timing mode in which data from soft X-ray events are not transmitted to Earth. Here we discuss the properties of this modified Timing mode, which will first be used in simultaneous XMM-Newton, RXTE, and INTEGRAL observations of the Galactic black hole binary Cygnus X-1 in autumn 2004. We discuss the predicted performance of this new mode based upon laboratory measurements, Monte Carlo simulations, and data from existing Timing mode observations.
ESA's large X-ray space observatory XMM-Newton is in its fifth year of operations. We give a general overview of the status of calibration of the five X-ray instruments and the Optical Monitor. A main point of interest in the last year became the cross-calibration between the instruments. A cross-calibration campaign started at the XMM-Newton Science Operation Centre at the European Space Astronomy Centre in collaboration with the Instrument Principle Investigators provides a first systematic comparison of the X-ray instruments EPIC and RGS for various kind of sources making also an initial assessment in cross calibration with other X-ray observatories.
Since December 1999, ESA's large X-ray space observatory XMM-Newton operates in a highly eccentric 48-h orbit which allows for long uninterrupted exposure times. The three payload instruments EPIC, RGS, and OM yield scientific data of high quality and sensitivity. We report here on the current timing capabilities of all three instruments by showing results from analyses on relative and absolute timing. In this context we discuss the process of correlating local onboard event arrival times to terrestrial time frames and present some detailed results from time correlation analyses. This involves investigations on the performance of the onboard quartz oscillator that have been performed. In addition we describe problematic timing data anomalies in the EPIC-pn data and their treatment by the SAS. We show recent examples of timing analyses.
The EPIC-pn CCD Camera on board the ESA X-ray observatory XMM-Newton is a very sensitive and versatile instrument with many observing modes. One of the modes, the timing mode, was designed so that a time resolution of 0.029 milliseconds can be achieved. This mode is important for observing bright variable sources with a very high time resolution. Up to now it has only been possible to use the spectra down to 300-400 eV in this mode. Below this energy the data appears to be affected by soft flares which are caused by stack overflows generated by high energy particles. We present a method that can be used to mitigate the effect these flares have on the data and discuss the improvement that this brings to the timing mode spectra. This new method will at last make it possible to get spectra down to the lowest energies detectable in this mode. This is particularly interesting for timing studies of isolated neutron stars and other variable objects, such as magnetic CVs, with very soft spectra.
We report on the current status of the background calibration of the EPIC pn-CCD camera on board XMM-Newton. The intrinsic background is comprised of internal electronic noise, and continuous and fluorescent X-ray emission induced by high-energy particles. Soft protons passing through the X-ray telescope (and finally also true cosmic X-rays) contribute to the registered events. The camera background has been monitored by using data in closed filter positions for three years; we review the spectral, spatial, and temporal distribution, for all commissioned instrument modes.
This paper also discusses briefly the effects on scientific data analysis and conclusions for further observations and detectors.
The XMM-Newton observatory has the largest collecting area flown so
far for an X-ray imaging system, resulting in a very high sensitivity
over a broad spectral range. In order to exploit fully these
performances, an accurate calibration of the XMM-Newton
instruments is required. This calibration is being continuously
updated, in order to refine the stable calibration parameters as well
as to account for the detector response changes induced by radiation damage. We report here on the current overall status of the EPIC/MOS cameras calibrations, and in particular on the recent work involving Charge Transfer Inefficiency evolution and recovery.
We describe in-orbit measurements of the mirror vignetting in
the XMM-Newton Observatory, using observations of SNR G21.5-09 with the EPIC imaging cameras. The instrument features that complicate these measurements are briefly described. We show the spatial and energy dependences of measured vignetting, outlining assumptions made in deriving the eventual agreement between theory and measurement. Alternate methods to confirm these are described. We briefly describe an analysis of the stray-light rejection of the telescope.
The pn-CCD camera on board of XMM-Newton as well as the Wide Field Imager (WFI) currently being designed for the XEUS mission can be read out in special fast timing modes, providing spectroscopy at very high time resolution. The two fast modes, Timing and Burst mode, of the pn-CCD camera on board XMM-Newton provide a time resolution of 30 μs, respectively. However, this fast timing is only possible at the expense of spatial resolution in readout direction. In contrast, the current baseline design of the WFI for XEUS will provide 25 μs timing at full spatial resolution. We describe the basic principles of the fast readout schemes of the pn-CCD and the SFI, discuss the potential of XEUS for high time resolution spectroscopy and present first results of pulse phase resolved spectroscopy of the Crab pulsar with the pn-CCD in Timing mode.
After the launch of Chandra, it was realized that low energy protons (below approximately 300 keV) are funnelled by grazing incident mirrors onto the focal plane detectors. Front illuminated CCD detectors are very sensitive to soft protons causing radiation damage in their electrode structures and transfer channels. The back-illuminated 280 micrometer thick fully depleted pn-CCD of the European Photon Imaging Camera (EPIC) on board the X-ray Multi Mirror mission (XMM) is by far less sensitive to low energy proton radiation. Commanding the camera in a special low gain mode, even allows to directly measure proton spectra and event patterns up to 300 keV per pixel. At the 3 MV Van-de-Graaff accelerator of the Institute for Physics in Tubingen we have irradiated and tested a 3 cm2 flight-like pn-CCD with protons from 1 to 300 keV up to a fluence of 1.4 (DOT) 109 protons/cm2. This is about a factor of 1000 above the expected solar proton fluence for a 10 year XMM-Newton mission under nominal operational conditions. In this paper we given an overview of the proton irradiation experiment, discuss the performance of the detector after proton irradiation and finally present proton spectra directly measured with the pn-CCD on board XMM-Newton during solar flares. In addition, we briefly describe the precautionary measures taken to minimize the proton radiation dose of the EPIC CCD detectors in orbit.
The combined effective area of the three EPIC cameras of the XMM-Newton Observatory, offers the greatest collecting power ever deployed in an X-ray imaging system. The resulting potential for high sensitivity, broad-band spectroscopic investigations demands an accurate calibration. This work summarizes the initial in-orbit calibration activities that address these requirements. We highlight the first steps towards effective area determination, which includes the maintenance of gain CTI calibration to allow accurate energy determination. We discuss observations concerning the timing and count-rate capabilities of the detectors. Finally we note some performance implications of the optical blocking filters.
On 10th December 1999, the European X-ray satellite XMM, now called XMM-Newton, was successfully put into orbit. After initial commissioning of the satellite's subsystems, the EPIC-pn camera was switched on and tested thoroughly in the period Jan./Febr. 2000. After refining of some of the parameter settings and the on-board pn-computer programs, we started the Calibration and Performance Verification Phase, which will last until the end of May 2000. In this paper we report on the results of the EPIC-pn Commissioning Phase with respect to the in-orbit performance of the camera. We also show some of the early results with the pn-camera, the first light image of a region in the Large Magellanic Cloud, and an observation of the Crab Nebular.
In the near future the European x-ray satellite XMM will be launched into orbit. The satellite is equipped with a PN-CCD camera with a sensitive area of 60 mm X 60 mm, integrated on a single silicon wafer. The same camera is on board of the German x-ray satellite ABRIXAS. The main feature of this camera type is the very good quantum efficiency of more than 90 percent in the energy range from 0.3 to 10 keV and the high time resolution, selectable between 7 microsecond(s) ec and 280 msec. All flight cameras are extensively calibrated, utilizing the long beam test facility Panter in Muenchen, the Synchrotron Radiation Facility beam lines at the Institut d'Astrophysique Spatiale in Orsay, and the PTB beam line at the Bessy Synchrotron in Berlin. We will give an overview of all the calibrations and calibration methods as well as some global results.
The pm-CCD camera is one of the three focal plane instruments of the European Photon Imaging Camera (EPIC) on board the x-ray multi mirror (XMM) mission scheduled for launch in August 1999. The detector consists of four quadrants of three pn-CCDs each, which are integrate don one 4 inch silicon wafer. Each CCD has 200 by 64 pixels with 280 micrometers depletion depth. One CCD of a quadrant is readout at a time, while the four quadrants can be processed independently of each other. Observations of point sources brighter than 11 mCrab in imaging mode will be effected by photon pile-up. However, special operating modes can be used to observe bright sources up to 150 mCrab in Timing Mode with 30 microsecond(s) time resolution and very bright sources up to several Crab in Burst Mode with 7 microsecond(s) time resolution. We have tested and calibrate the flight model FM of the EPIC pn-CCD camera at the long beam test facility Panter near Munich and at the synchrotron monochromators of the Institut d'Astrophysique Spatiale in Orsay, France. In this paper describe the calibration of the pn-CCD detector in high time resolution/bright source operating modes and present preliminary results on the performance in these modes.
The x-ray multi mirror (XMM) mission, the second cornerstone of the European Space Agency's Horizon 2000 program, will be launched in August 1999 and will perform high throughput imaging and spectroscopy in the energy range form 0.1 to 15 keV. One of the focal plane instruments is the EPIC pn CCD camera with a sensitive area of 60 mm by 60 mm, integrated on a single silicon wafer. The camera is divided into 4 redundant quadrants of three 10 mm by 30 mm CCDs with 64 by 200 pixels each. The thin entrance window in combination with a depletion depth out modes give the flexibility to observe targets of different source strength up to several Grab with some reduction in spectral and spatial performance. We will report on the calibration of the flight unit of the EPIC pm camera, performed at the long beam test facility Panter in Muenchen and at the Synchrotron Radiation Facility beam lines at the Istitute d'Astrophysique Spatiale in Orsay. In this paper we describe the preliminary results of the calibration of the imaging modes.