= [wiki:Notes]/Miriad Calibration Tables =


Types of calibration tables: 
 * Gain
 * Bandpass
 * Leakage

Current miriad formats:

{{{
#!rst
gains
=============
The gains table contains nants complex antenna gains for nfeeds feeds + ntau delays and nsols solution intervals. 
ngains=(nfeeds+ntau)*nants, ntau=0 (no delay solution) or 1 (delay solved for).
Possible extension: record a separate gain for each spectrum, ngains=(nfeeds*nspect+ntau)*nants.


======  ==============  =========
offset  value           length
======  ==============  =========
0       0               4
4       undef           4 
8       julian date     8
16      gains           8*ngains
(last 2 lines repeat nsols times)
=================================


bandpass
========
The bandpass table contains nchan * npol * nants complex channel gains.
The value nchan is the sum of all channels in all frequency bands, npol=1 or 2.

======  =================== ==================
offset  value               length
======  =================== ==================
0       0                   4
4       undef               4 
8       g(nchan,npol,nants) 8*nchan*npol*nants
======  =================== ==================

in Aug09 a time field was added to allow for multiple bandpass solutions

bandpass v2
========
The bandpass table contains nchan * npol * nants *nbpsols complex channel gains.
The value nbpsols is the number of bandpass solutions, each applies to a separate time range.
The value nchan is the sum of all channels in all frequency bands, npol=1 or 2.

======  =================== ==================
offset  value               length
======  =================== ==================
0       0                   4
4       undef               4 
8       g(nchan,npol,nants) 8*nchan*npol*nants
8       julian date         8
(last two lines repeat nbpsols times)
======  =================== ==================





freqs
=====
A separate table "freqs" is maintained with the frequencies for each of nspec bands (or spectra).
The item freq is the frequency for the first channel, df gives the channel spacing

======  =================== ==================
offset  value               length
======  =================== ==================
0       0                   4
4       undef               4 
8       nschan              4
16      freq                8
24      df                  8
(last 3 lines repeated nspec times)
==============================================


leakage
=======
polarization leakage parameters or D terms.
There are 2 complex D term parameters per antenna.

======  =================== ==================
offset  value               length
======  =================== ==================
0       0                   4
4       undef               4 
8       D(2,nants)          8*2*nants
======  =================== ==================


}}}