Introduction and command syntax

The pipeline automatically performs all of the steps described in the interactive session below, with the exception of the astrometry. The full command is as follows:

npoipipe, confiles, calibrators=calstars,addcal=calstar,model=modelfile

confiles is a string file specifier given to IDL's file_search function to return a list of files for processing. If confiles is omitted, all CONSTRICTOR files in the current directory are processed.

A list of calibrators to be used can be specified as a string array for the calibrators keyword, otherwise npoipipe will determine which stars can be used as calibrators based on information found in the standard NPOI calibrator list (diameter.bsc). Calibrators can be added to the standard list using the addcal keyword. It is thus important to keep in mind that npoipipe will normally use all calibrators observed to calibrate the science targets. If not enough calibrators were observed, a warning message will be displayed, and processing will continue with the next data file.

Finally, the model keyword can be used to pass the name of a model file which will be used to flag data on non-tracking baselines. Non-tracking (reference) baselines are difficult to detect, and the method used by npoipipe is based on the delay jitter, which is compared to the median value derived from all calibrator observations (in the same data file). If, despite this initial step, the (calibrated) visibility measured on a baseline is less then half of what is predicted by a model, the baseline is considered to have been tracking noise, and all values are flagged.