Overview of 6-station data reduction

The reduction and calibration of NPOI 6-station data is of course similar to the one performed on 3-station data, but there are differences mostly related to complexity.

What do we do in this exercise ?

In this example, we reduce a data set of Eta Virginis observed on 2002-02-15. If you want to skip the exercise outlined in the next section of looking at a raw data file, begin here with reading the 1s averages of visibilities and other data.


HDS-file opened; mode=READ.
Scantable created.
GeoParms loaded.
GenConfig loaded.
Warning(DAT_FIND): component not found (METROCONFIG)!
Backgroundtable created.
Background data loaded.
Fixed early day configuration.
StarTable created; number of entries = 11.
Finished reading catalogs.
Finished reading catalogs.
Number of new diameters added: 11.
Number of new (R-I) values found: 0.
Finished reading catalogs.
Allocated arrays for 62 scans in 2 ob's; MB = 6, MC = 16, MP = 1498
Reference station set.
Dispersion corrected delays initialized.
% Compiled module: POLY.
Data loaded.
Scan log read.
Observer log read.

In order to produce more readable delay plots, we update the currently loaded baseline coordinates with those determined from a previous reduction of these data.


StationTable created; StationCoord updated.

At this point let's bring up the main GUI (or widget) which, besides the IDL command line, provides another way of communicating with the software.


In the following exercises, both widgets and command line procedures are going to be used for the data analysis. Plotting, because of the many selections and options, is done most easily through widgets with a fixed functionality. However, at any time, regular IDL commands can be issued, providing a truly interactive and flexible environment.

Note that some images of widgets in this document are clickable for more detailed explanations.