XMM-Newton Optical Monitor Data Processing with SAS
"X-Ray and Radio Connections" workshop
XMM-Newton mission extension
At the November 5/6 meeting of the Science Program Committee the mission extension of XMM-Newton up to 31-March-2008 was unanimously approved. This means that the funding up to 31-March-2006 has been secured, and the principle of an extension has been approved up to 31-March-2008, with a provisional budget.
Many, many thanks to all the XMM-Newton supporters out there, who have greatly helped to make the mission a success.
Post solar flare instrument and spacecraft status
Following the severe Solar flaring activity which affected revolutions 712 through 716, with the spacecraft in a safe configuration, and with Rev.717 used for certain instrument health checks and calibration, initial calibration analysis indicates that the instruments have suffered little, if any, degradation as a result of the flares.
For EPIC, no change is seen in Charge Transfer Inefficiency (CTI) or energy resolution for the MOS or pn cameras, within the precision of the measurements.
For RGS, no detectable change is seen in the system peak (essentially the dark signal) for either RGS instrument. Minimal change is observed in the contaminating effects of hot columns: two cases of adjacent hot pixels (two pairs of hot pixels) have appeared in RGS1 only, well separated from celestial X-ray photons.
For OM, sensitivity checks on Rev.718 showed that high responsivity values recorded during the flares had returned to normal. Stellar photometry returned values in agreement with earlier measurements on the same targets.
All checks performed at spacecraft level (solar arrays etc.) also show no sign of degradation as a result of this event.
XMM-Newton Image Gallery
We have prepared an XMM-Newton Image Gallery into which scientists who have remarkable and/or high quality images and results related to XMM-Newton are invited to submit examples. The images are intended to be used for educational or informational purposes.
As a starting point we selected some interesting figures from journals and included several examples already kindly provided by some of you.
Please note that the success of the XMM-Newton Image Gallery strongly depends on your input and we therefore encourage you to submit all your exciting XMM-Newton results. The submission can be done via a web form linked from the Gallery front page, and which is also available at URL: http://xmm.esac.esa.int/external/xmm_science/gallery/public/submit.php
This form allows you to upload your result and to enter detailed information like image title, figure caption, observation details and credits. The information will be placed in a temporary database where it will be reviewed by the maintainer of the image database before being added to the XMM-Newton Image Gallery.
If further information or assistance is needed, please contact us via the XMM-Newton Helpdesk (xmmhelp@sciops.esa.int).
Hoping that you can help us in further promoting the XMM-Newton project via this image gallery.
XMM-Newton Optical Monitor Data Processing with SAS
OM data processing with SAS is achieved by running two chains: omichain and omfchain, for image mode data and fast mode data respectively. These chains consist of a concatenation of SAS tasks which perform aperture photometry on both types of data, producing source lists containing all objects detected in the image data, and producing time series for the fast mode data. An interactive task, omsource, allows the user to perform the photometry by selecting the objects in the image using the cursor. For the detected objects, measured count rates can be converted into fluxes at the effective wavelength of all the filters.
The critical point in the processing of OM data has always been the detection of the sources present in the image data. The automatic detection is very sensitive to image artifacts and background, which unfortunately are present in OM data due to straylight.
Over the years, SAS has evolved considerably in handling these features, and tasks such as omdetect and omsource are now very robust and efficient.
The correct processing of fast mode data is also affected by the proper detection of the source (or sources) within the small fast mode window, particularly in cases of slight off-centering of the source. Big progress has been made with respect to this also.
Accurate knowledge of the PSF for all the filters will be incorporated into the system with the imminent release of the corresponding CCF.
The data obtained with the OM grisms (UV and Visible), although in image mode, were not processed up to now, due to the lack of algorithms to extract the spectra, and a lack of calibration for both of them.
The next release of SAS, Version 6, due early in 2004, will have solved all of the above mentioned problems. In addition, it will contain a new chain, omgchain, to extract and fully calibrate OM grism data.
This history of steady progress in improving the OM processing underlines the fact that XMM-Newton users, including those gathering data from the XSA archives, should always reprocess their data with the latest SAS version to achieve the maximum accuracy in their results. With the release of SAS 6 in early 2004 users will get the benefit of the very latest progress. But it is well worth remembering that the current version, 5.4.1, gives correct answers for image data, when it is complemented by the omsource interactive task, though fast mode processing may still have small uncertainties in certain datasets. Therefore users with data processed with SAS versions earlier than 5.4.1 have, for some time, had the option of benefiting significantly from a reprocessing with that version. This can usefully be done even before SAS 6 comes on line. In general, in any reprocessing one should always make sure to use the latest calibration files (CCF's), as this has obvious benefits.
Planned general reprocessing
Importantly, SAS 6 will incorporate significant advances in the handling of data from all XMM-Newton instruments.
The Survey Science Centre envisages the reprocessing, with this coming SAS version, of all archival data from all three instruments, in order to homogenize the contents of the archive with respect to algorithms and calibrations applied to the XMM-Newton data. With that reprocessing, all of the contents of the archive to date will have been processed to a "state-of-the-art" level.
"X-Ray and Radio Connections" workshop
The Chandra X-Ray Center, Los Alamos National Laboratory, and the National Radio Astronomy Observatory are pleased to announce the "X-RAY AND RADIO CONNECTIONS" workshop; a meeting focused on scientific areas where cross-fertilization between theory and observations in both X-ray and radio wavebands provides a key to underlying physical processes.
The meeting will be held in the sunny and historic town of Santa Fe, New Mexico (USA) from Tuesday February 3, through Friday February 6, 2004. Early registration for the meeting ends December 1st, 2003.
This meeting focuses on the following scientific topics:
Massive star cluster outflows
Colliding stellar winds
Supernova remnants
Pulsar wind nebulae
Dissipation of jets and lobes
Cluster mergers
Please visit the following website for more information: http://www.aoc.nrao.edu/events/xraydio
This website will be updated regularly with additional information.
Kristy Dyer (NRAO), Lorant Sjouwerman (NRAO) and Robert Coker (LANL)