Configuration and Initialisation Files.

The ``hardware'' configuration of the interferometer is listed in several files:

• inter_base:config.dat
  This file indicates some basic array parameters, specially the time corrections. It should never be changed by operators or astronomers.

• inter_base:general.ank
  These files contain antenna dependant parameters, such as pointing constants, focus and homology parameters. The parameters change only when the antenna is repaired or modified.

• inter_base:tij.ank
  These files contain parameters for antenna k on station Tij (e.g. W00, not W0): IAZ, IEL, IVE, IVN, DVE, DVN, position errors dX,dY,dZ and delay offset. They have to be updated each time the antenna is set on station.

• inter_base:start.obs
  This procedure indicates on which stations the antennas are currently located. It also indicates which is the antenna connected to the single-dish backends.

• inter_base:memory.obs
  

  This procedure is automatically executed when OBS starts, and updated when it finishes. It can also be updated using command SAVE. It defines the current status of the OBS program.

• inter_base:attenuation.dat
  

  This file contains the calibration data for the programmable attenuators in the receiver IFs.

• inter_base:feff.dat
  

  This file contains the forward efficiencies as a function of frequency for the antennas.

• inter_base:jykel.dat
  

  This file contains the Kelvin to Jansky calibration factors as a function of frequency for the antennas (inversely proportional to the aperture efficiencies).

It is of the utmost importance that these files be kept up to date.

These files should in practice never be edited using a text editor (with the exception of the general.ank files, and only after authorization). A special language in OBS has been implemented to allow modifications of the array configuration parameters: language SET $\backslash$, which is available only in the CONFIGURE mode (see appropriate section). These files should not be purged as they are used for bookkeeping. Also, do not modify pointing constants using directly the shell command put.