# Overview of the AP pipeline¶

lsst.ap.pipe is a data processing pipeline for Prompt Data Products. It is a Command-Line Task which operates on ingested raw data in a Butler repository. It also requires appropriate calibration products and templates. As it runs, ApPipeTask generates calibrated exposures, difference images, difference image source catalogs, and a source association database.

The initial motivation for lsst.ap.pipe, information about one of the original test datasets, and an outdated tutorial are available in DMTN-039.

1. ProcessCcdTask, which in turn calls lsst.ip.isr.IsrTask, lsst.pipe.tasks.CharacterizeImageTask, and lsst.pipe.tasks.CalibrateTask to perform image reduction as well as photometric and astrometric calibration;
2. ImageDifferenceTask, which uses many utilities from lsst.ip.diffim; and
3. AssociationTask, which makes a catalog of Difference Image Analysis (DIA) Objects from the DIASources created during image differencing.