Status
IN PROGRESS
Stakeholders

Steven Myers Frank Schinzel Aaron Lawson Anthony Graham [X] Mark Lacy 

Outcome

We will look into improving the model.

Mark says to continue including affected data in SRDP and do not flag the data. In comparison to the recent 3C147 model issue, we do not see ramps in amp vs freq solutions. Include a QA note:

"The 3C286 Ka-band model used for pipeline processing and packaged with CASA does not represent the source in A-configuration very well, causing amplitude errors. A new, more accurate model will be released with CASA in the future."

"The current calibrator models for resolved flux density calibrators in A-configuration in CASA are created

with narrow band data. At the high frequencies of a broad band observation, this can mean that the calibrator

model does not represent the structure of the calibrator very well, leading to amplitude errors that reduce

the dynamic range of the calibrated data. This will be remedied in a future version of CASA and the pipeline."


Due date
Owner

Anthony Graham [X] 

Background

Data sets show short baselines at the end of E and W arms with high amps in the amp vs uvwave plots. Paul suggests the long baselines have too much power in comparison. Juergen suggests S band may also be affected.


Example plot from original CIPL run for 22A-012.sb41313612.eb41801998.59714.25389122685:

Same data set/plot using a model for 3C286 made at 33 GHz (slightly lower Amp values):

Same data set/plot using a model for 3C286 made at 26 GHz (same as original model):

Likely the same issue for 3C147 - plot from 20B-342.sb39244407.eb41801147.59713.02153945602:




Tests/New Info:

Aaron: Ran the 3C286 data through AIPS and got the same result as above. Showed the 3C286_A.im model that comes with CASA to Rick and he wasn't impressed by it. Rick gave me a fits image of 3C286 at 37GHz, A-band. I then used a script provided by Frank, written by Kumar, to turn the fits image into a model CASA image. I manually calibrated the same 3C286 data as above but used this new model image in my setjy call to get the below plot. A more official pipeline run that will use that model is going in: /lustre/aoc/sciops/alawson/test/22A-012/pipelineNewModel . I suspect that run will also show a correct Amp vs UVwave plot once it is finished. We should probably think about revisiting/verifying the all the models that come with CASA.


preview url image

Action items

  •  


1 Comment

  1. Frank Schinzel

    I suggest trying models with higher rasterization when you encounter such issues. If that fixes the problem, then it is for sure the discrete rasterization at too low resolution that is causing these discrepancies.