Catalog Processing

The CSC is created by processing each Chandra dataset with a series of automated data analysis pipelines. Collectively, the pipelines are known as "Level 3 Processing" and the data products are named as such, e.g. the event file is evt3.fits. The nomenclature follows Chandra Standard Data Processing, which produces the Level 1 and 2 Chandra data products.

The pipelines run in order:
Calibrate Pipeline » Detect Pipeline » Source Pipeline » Master Pipeline

Observation Selection

The Observation Selection page describes which observation intervals (OBIs) are chosen for catalog processing.

Calibrate Pipeline

The calibrate pipeline is run for each OBI chosen by the observation selection process.

• Reprocess the datasets with the same CALDB
• Identify and remove background flares
• Create data products for use in the other pipelines

Detect Pipeline

The detect pipeline is run for each calibrated OBI from the calibrate pipeline.

• Create high and low frequency background maps
• Detect source candidates with wavdetect
• Combine detections
• Calculate the source and background regions
• Calculate the limiting sensitivity

Source Pipeline

The source pipeline is run for each detection region created in the detect pipeline.

• Measure the source and PSF size; flag extended sources
• Create light curves and look for variability
• Perform spectral fitting to get flux
• Calculate additional source properties (e.g. position errors)

Master Pipeline

The master pipeline is run for each OBI which other OBIs overlap spatially to match sources identified in the source pipeline.

• Match sources from different OBIs
• Determine master source properties from the OBI entries
• Package the data for inclusion in the CSC