Logged on 07/10/2009 01:01:59 PM
This section describes the first proper calibration step.
Click the 'TDL Options' button again and this will bring up the compile-time menu. Everything should be as it was for the previous step. We want to do some calibration now so expand the 'What we want to do' menu, check 'Calibrate' and make sure we're calibrating on visibilities. Enable 'subtract sky model' and 'correct the data or residuals'.
This time we'll also solve for the values of a 2x2 gain matrix, the so-called G-Jones matrix. Select the 'Use G-Jones (receiver gains/phases)' option, and check the 'Use FullRealImag module' box. This solves for the real and imaginary parts of this matrix simultaneously.
Click compile and it will build a tree.
Examine the run-time options below. The tile size is still set at ten, but we're also setting the solution sub-interval (sub-tile) for time to 1 and leaving frequency as 'none'. You can use this to set the number of solutions per tile, e.g. setting both to 1 would result in one solution per time and frequency point. We know that the gains are stable in frequency and variable with time, hence these values. One solution per time slot is more computationally expensive but it's also more accurate.
Don't forget about bookmarks!
When you're ready, open a bookmark or two: 'inspector G' and the residuals are always useful.
If you wish you can also perform solutions for the off-diagonal terms of the G-Jones matrix, either subsequently or simultaneously.
Click the 'Calibrate G diagonal terms' button and examine the 'inspector G' bookmark to see your gain solutions.
![]() |
|