Manpage of axcor
Section: User Commands (1)
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axcor - Apply special processing options to uv-data.
AXCOR is a MIRIAD task which applies special processing options
to uv-data. By default, AXCOR applies the calibration files
before it processes the uv-data into the output file. It was
cloned from UVCAL.
The names of the input uv data sets. Multiple names can be given,
separated by commas. At least one name must be given.
The normal uv selection commands. See the Users manual for details.
The default is to process all data. Note that window selection can
not be used with options=hanning, passband, contsub, or wide.
Source right ascension and declination. These can be given in
hh:mm:ss,dd:mm:ss format, or as decimal hours and decimal
degrees. Setting RA and DEC will change the phase center to
the RA and DEC specified. The default leaves the data unchanged.
This gives extra processing options. Several options can be given,
each separated by commas. They may be abbreivated to the minimum
needed to avoid ambiguity. Possible options are:
and imaginary parts of each spectral window.
Exclude badchan and endchan specified below.
by dividing the cross correlations by the
geometric mean of the autocorrelations.
changes. This option also corrects the phase difference
between the wide channels due to line length.
options=linecal,avechan remakes the wideband from
the channel data after the phase slope is removed.
where chi is the parallactic angle for Alt-Az antennas.
Can be used when the source is strong. e.g. for
planets. The passband is estimated from the lsb,
smoothed within each spectral window, and applied
to the lsb data. The complex conjugate is applied
to the usb. This corrects for time variable IF
passband errors. The uv-data must contain the same
spectral windows in both sidebands of LO1.
'uvrotate' Rotate uv-coordinates from current to standard epoch.
The standard epoch, ra, dec can be changed using PUTHD.
'avechan' Average unflagged spectral channels. Make new wideband.
excluding badchan and endchan specified below.
'slope' Fit phase slope for each spectral window. Make new wideband.
wideband phase is slope in units radians/GHz, and can
be used to fit delay and antenna positions using BEE.
Exclude badchan and endchan.
Enable other MIRIAD tasks to analyze interferometer pointing data.
replace [u,v] with [dazim,delev] for ant1 in each baseline.
if(dazim(ant1).eq.0 .and. delev(ant1).eq.0) then replace [u,v] with
[dazim,delev] for ant2 in each baseline. If both ant1 and ant2 have
zero dazim and delev, then [u,v] = [0,0]. [u,v] are in arcsec units.
The data can be calibrated using select=uvnrange. N.B. not "uvrange".
e.g. uvcal options=holo vis='infile' out='outfile'
selfcal vis='outfile' 'select=uvnrange(0,1)' options=amp flux=1
Beam profiles can then be analysed using standard programs. e.g. UVPLT.
Holography images of antenna surfaces are made using INVERT and IMHOL.
INVERT makes a real image; options=imaginary makes the imaginary part.
IMHOL combines the real and imaginary images into amplitude and phase
images of the antenna surface.
Related tasks: VARMAP makes images versus [dazim,delev] directly.
NOTE: Options=nochannel cannot be used with "hanning", "passband"
and "contsub". For these 3 options no processing is performed on the
Number of ranges of bad channels followed by list of up to 20 pairs
of numbers giving range of channels to exclude in options=contsub
and options=avechan. E.g. badchan=3,1,3,15,16,256,257
excludes the 3 ranges (1,3) (15,16) and (265,257)
Number of channels to drop from the ends of each spectral
window in options=passband, contsub, and avechan. Default=0.
Number of channels to average in options=passband. Default=1.
Rms noise level used to flag data in options=contsub. All channels
are flagged if the rms noise level per channel is greater than sigma
after subtracting the continuum. Endchan and badchan are not included
in computing the rms. The default is sigma=0. which does not flag
Multiply the data and wideband by cmplx(scale1,scale2). Two values.
Default is no scaling. If only one value is given it is assumed to
be a real value. E.g. scale=0,1 multiplies the data by sqrt(-1)
Subtract a complex valued offset from the uv-data. Two values give
itude (after calibrations have been applied by uvcal)
phase in degrees. Default is none.
Subtract a source model from the uv-data. Three values
give the flux density [Jy], scale [nanosecs], and index
for a radial power law:
model = flux * (uvdist/scale) ** index
The model visibility is subtracted from the uv-data.
Default model=0,0,0. i.e. no model is subtracted.
Subtract the source polarization from the uv-data. Two values
give polarized intensity, Ip, and position angle, 2*psi, in degrees.
Use same amplitude units as uv-data after calibration is applied..
subtract Ip*expi(2*psi)*expi(-2*chi) from LR, and
subtract Ip*expi(-2*psi)*expi(2*chi) from RL
where chi is the parallactic angle for Alt-Az antennas.
Default=0,0. is no correction.
After subtracting the source polarization, the averaged uv-data
gives the instrumental polarization for each baseline.
Change the polarization code. Default polcode=0 makes no change.
Polarizations are YX,XY,YY,XX,LR,RL,LL,RR,-,I,Q,U,V
Polarization codes -8,-7,-6,-5,-4,-3,-2,-1,0,1,2,3,4
E.g. polcode=4 changes YX,XY,YY,XX to LR,RL,LL,RR
E.g. polcode=-4 changes LR,RL,LL,RR to YX,XY,YY,XX
Rotate uv coordinates and hence image by parot degrees.
Rotation is +ve to the E from N. i.e. increasing PA.
Default is no rotation.
Amplitude correction for atmospheric coherence, specified by
the FWHM in arcsec, of a circular Gaussian fit to
the phase calibrator(s) for the target source.
Default seeing=0. is no amplitude correction.
Axis offset correction. Remove elevation dependent phase changes
due to axis non-intersections. Inputs are AX1,AX2,AX3,AX4,... in nsec.
Elevation dependent focus correction, assuming sin(el) dependence.
Inputs are F1,F2,F3,.... in nsec
Visibility scaling. Multiply data by amp*exp(i*pha).
Inputs are Amp,Pha for all antennas.
The name of the output uv data set. No default.
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This document was created by
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Time: 18:35:38 GMT, July 05, 2011