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lofar-astron / DP3

DP3: streaming processing pipeline for radio interferometric data
GNU General Public License v3.0
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Frequency not found in h5 file #326

Open ErikOsinga opened 3 years ago

ErikOsinga commented 3 years ago

Hi,

I am trying to apply solutions with DPPP using the following command:

DPPP 

msin=./TC003.MS
msin.datacolumn=MODEL_DATA
msout = .
msout.datacolumn=MODEL_DATA
cor.invert=False
cor.parmdb=./cal-amp1-c00-ddcal0016-cdd06.h5
cor.correction=amplitude000
numthreads=24
steps=[cor]
cor.type = applycal

but I am getting the error that the frequency of my MS is outside of the frequencies in the solution file. std exception detected: Frequency 62767028.808594 not found in sol000/amplitude000

Is there no extrapolation at all in DPPP?

tammojan commented 3 years ago

There is a bit of extrapolation at the beginning and end of the solutions. For example, if you have solutions at 10, 20, 30, 50 MHz and use nearest-neighbor interpolation (the default), DPPP will accept frequencies from 5MHz to 60MHz, i.e. it assumes that the cell width of the first and last cell are symmetric. See https://git.astron.nl/RD/schaapcommon/-/blob/master/src/h5parm/soltab.cc#L518

tammojan commented 3 years ago

As discussed with Reinout and Francesco, we can extrapolate a bit further which will accommodate some common cases of averaging. Merge request here: https://git.astron.nl/RD/schaapcommon/-/merge_requests/24