/ csc / data_products /

CSC 2.1 Data Products

CSC 2.1 comprises two types of data products: database tables and file-based data products. The data is organized hierarchically, with source properties categorized into three levels - master level, stack level, and per-observation level. This hierarchy results from stacking individual Chandra observations to improve the signal-to-noise ratio. Stacking happens only when observations have pointings within 1 arcmin of each other, and it may detect a single source in multiple stacks. The master-level properties represent the best estimation of source properties, leveraging information from all contributing stacks.

For accessing these data products, see How to Access CSC 2.1.

Chandra Source Catalog version 2.1 Data Products
Database Tables	File-based Data Products
Database Tables	Regions A rectangular region of interest around a source	Full-Field The entire field of view of an observation
Master Sources Table The Master Sources Table lists the best estimates of source properties for each X-ray source in the catalog, derived from all individual observations comprising the highest-exposure flux-ordered Bayesian block.	Overview Bayesian block source properties Per-master source region aperture photometry Per-master extended source region polygons A set of master source file-based data products created for each identified source that undergoes catalog processing.
Stacked Observation Dections Table Each identified X-ray source in the sky is represented in the catalog by one or more "stack detection" entries—one for each stack where the source has been detected. The individual stack entries record all of the properties of a detection extracted from a single stack and associated file-based data products, which are stack-specific.	Overview Valid stack source region event list Valid stack source region image Valid stack source region tricolor image Valid stack source region exposure map Detect stack source region Valid stack MLE source fit draws Valid stack source region aperture photometry PDF The source-region, stack detections data products are the combined per-source files found in the bundle that the master source falls on, obtained from individual stacked observations (or "stacks") filtered by a rectangular region of interest around the position of the detection. These files are for the large part generated in the Source Properties pipeline run for each master source produced by the Master Match pipeline.	Overview Stack Source Region Event List Detect stack image Detect stack background image Detect stack exposure map Detect stack field of view Detect stack limiting sensitivity Merged source detection list A set of stacked, full-field observation detection data products is created for each observation stack that undergoes catalog processing.
Per-Observation Detections Table Each identified distinct X-ray source on the sky is represented in the catalog by one or more "source observation" entries The entries per observation record all of the properties of a detection extracted from a single observation and associated file-based data products, which are observation-specific.	Overview Per-ObsId source region event list Per-ObsId source region image Per-ObsId point spread function image Per-ObsId source region exposure map Per-ObsId source region PHA spectrum Per-ObsId source region ancillary response file Per-ObsId source region response matrix file Per-ObsId source region light curve Per-ObsId source region Valid Per-ObsId MLE source fit draws Per-ObsId source region aperture photometry PDF The source-region, pre-observation detections data products are extracted from individual observations filtered by a rectangular region of interest around the position of the detection. These files are for the large part generated in the Source Properties pipeline run for each master source produced by the Master Match pipeline.	Overview Per-ObsId event list Per-ObsId image Per-ObsId background image Per-ObsId exposure map Per-ObsId aspect solution (includes fine astrometry updates) Per-ObsId aspect histogram Per-Obsid bad pixels Per-ObsId field of view Per-ObsId pixel mask Per-ObsId extended source region polygons A set of full-field (i.e. observation-based) data products is created for each observation that undergoes catalog processing.
Master Source/Stacked Observation Detection Association Table This table maps Master Sources table records to their associated Stacked Observation Detections, and also identifies the type of linkage (unique, ambiguous, or non-detection) that associates the two.
Stacked Observation Detection/Per-Observation Detection Associations Table This table maps Stacked Observation Detections table records to their associated single observation detections.
Detect Stack Table The Detect Stack table records the mappings between observation stacks and the component observations that comprise the stacks. Although all the observations that are included in a stack are recorded in the Detect Stack table, observations that are part of the same stack may cover somewhat different sky regions and therefore overlap each other only partly.
Valid Stack Table The Valid Stack table records for each stacked observation detection the subset of observations within the stack for which the detection falls within the observation pixel mask that defines the valid pixels within the observation field of view.
Likely Stack Table The Likely Stack table records for each stacked observation detection the subset of observations within the stack that were used by the maximum likelihood estimator analysis to validate the candidate detection. For CSC 2.1, source detection is performed both on the full valid stack and on each of the single observations that comprise the valid stack, so the Likely Stack table record corresponding to a stacked observation detection will include either the entire set of observations included in the valid stack, or the single observation for which the likelihood was maximized.
Limiting Sensitivity Table The Limiting Sensitivity table records the catalog limiting sensitivity, defined as the minimum flux in an energy band required for a point source to be detected and classified as either MARGINAL or TRUE by the source detection process in that energy band, as a function of position on the sky. At present, access to the Limiting Sensitivity table is only available through CSCview or the Quick Search web interface.

/ csc / data_products /