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XMM-Newton Science Analysis System


esrcselect (esrcselect-1.7.2) [xmmsas_20050815_1803-6.5.0]

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Description

In the pipeline processing of XMM data, products will be created for individual sources detected in the EPIC cameras. The source products (spectra and time-series) will only be produced for a selected number of the detected sources (typically the brightest), and only in circumstances where the source products can be generated reliably.

The task esrcselect will make the decision on which sources are candidates for source product generation. The task accepts two sources lists: the observation source list and the exposure source list. The positions used to define source and background regions are drawn from the exposure-level source list.

The source selection criteria may differ depending on whether a spectrum or a time-series is to be produced, which is specified using the operationmode parameter. Currently there are no differences in the selection criteria, the operation mode merely defines which column in the observation source list will be updated to reflect the production of products.

The conditions for the selection of a source are currently anticipated to be:

1. Distance from its nearest neighbour (from exposure source list) greater than a specified threshold, to avoid producing products for confused sources
2. Count rate (from observation source list) exceeding a specified minimum, to ensure good statistics in a time-series
3. Count rate (from observation source list) not exceeding a specified maximum, to avoid extracting products for piled-up sources
4. Number of source counts (from exposure source list) exceeding a specified minimum, to ensure good statistics in a spectrum

Furthermore a limit can be placed on the number of sources selected. If the number of candidates would otherwise exceed this limit, the brightest sources in the observation will be preferrentially selected.

Additional conditions may be necessary; these will be added as needed after in-flight experience has been gained (see section 10).

For some instrument configurations (eg. observations including windowed or timing modes) sources in the observation source list may not have a counterpart in the exposure source list. In such cases the source will not be selected for source product generation.

The output from the task is a list of the selected sources, which is used as input to the task region. For each select source the file lists the source ID number (from the observation source list) and the source coordinates (from the exposure source list). The task also updates the observation source list, setting a flag for each source which has been selected for product generation.