The Remodel and Bigfit Programs

John M. Benson - Dec 2000


The Remodel Program

The Remodel program will apply a new interferometer model to a VLBI data set that was correlated on the VLBA Correlator. The data that is to be remodeled must be in AIPS, having been read into AIPS via the FITLD program. The Remodel program itself is not an AIPS task, rather it runs independently under Solaris or Linux on Sun Workstations or Pentium PC's.

Remodel updates an existng AIPS CL extension file with group delay, delay rate and phase corrections derived from the difference between the on-line correlator model and a new model. The old, on-line model is exactly recorded in the AIPS IM (Interferometer Model) extension file. The new model is calculated by calls to the CALC1 Server. The input parameters to the CALC Server, source and station coordinates, Earth Orientation Parameter, etc., are taken from either the AIPS AN, SU, CT, FQ, MC extension files or from a user created external file. In this way, changes in station or source parameters can be used to build a new model.

In order to run Remodel, you must run TBOUT in AIPS on seven extension files: AN, CL, CT, FQ, IM, MC, and SU. For example, to make an external AN table, run TBOUT like this :

task 'tbout';
inext 'an';
invers 1;
outfile 'fits:antable.lis';
docrt 400;
bcount 0;
ecount 0;
go tbout

It's a good idea to set up an AIPS runfile to TBOUT all seven tables at once.

To be continued. Work in progress.

1 CALC was developed by the Goddard Space Flight Center with assistance from other geodetic VLBI groups. It is maintained and distributed by Goddard as a service to the VLBI community.

The Bigfit Program