06/04/2023 Meeting notes -Sun Subtraction

[Victoria-Samboco]

From what was discussed today, were I presented the case where after subtracting the Model I was still having the sun in the field of view, after explanation I understand what is wrong (what I was doing was basically CORRECTED_DATA-MODEL_DATA -MODEL_DATA , making it introduce back the Sun to the visibility's, and I was also, without knowing treating the rephased to the Sun data and the rephased to the original visibility as different MS while they are the same), now its clear.

Recommendations:

1. Subtract the Model of the Sun from the visibilities and image the CORRECTED_DATA with niter =100 (making a large image enough to include the region where the Sun was, to make sure that its working);
2. It's not necessary to make a larger image after subtraction (it can be done only for analysis and quality control), in fact not always will be possible to do it, in this case its easy and possible because the Sun is close enough, a 8000x8000 image size can work in general (But in this case we want to picture Sagr A also, if I'm not wrong );
3. Suggestion of the use of the taql command for subtraction besides of wsclean.

Here are some results obtained from the last weeks:
These images illustrates before and after subtraction of the Sun:

You can find the last updates of the pipeline in solarkat, branch improvements

[Victoria-Samboco]

Results form the Subtraction process.
The images were imaged in the same conditions before ans after subtraction and we can see that after subtraction the aliasing also its not showing in the image as expected and the image quality appears to be better than before.