Methodology and use of AIPS

In the sequence of data reduction, first and foremost key step is the editing of bad data, and then follows the amplitude and phase calibration of the observed visibilities. The sequence of various AIPS tasks that were used for data reduction is described below. A typical AIPS task depends on a large number of parameters, called as `Verbs' and `Adverbs', which control the behavior of the tasks. The settings of the relevant parameters used in each of these tasks are discussed below:

1. The FITS file is imported into AIPS using task FITLD. This results into a multi-source visibility database, written in AIPS working environment.

2. The task INDXR was run to generate CL (ver 1) table. The task was run using following settings: CPARM(3)=1, for a time interval of 1 minute, which are made in CL (ver 1) table.

3. The flux density of the flux/primary calibrators must be accurately set before proceeding for further calibration. The flux density scale of the standard VLA flux calibrators 3C48, 3C147 and 3C286 is encoded in the task SETJY. This task was run using following settings: OPCODE='CALC', SOURCE='3C286, '3C147', '3C48', ''. OPCODE='CALC', which use the standard Baars et al. formulae and frequency information from the header and determines the flux densities of primary calibrators 3C286, 3C48 and 3C147.