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Basic Information on zeemap
Task: zeemap
Purpose: Map the magnetic field from I and V cubes
Categories: profile analysis
ZEEMAP tries to find the line-of-sight magnetic field splitting
a transition by measuring the shift in the line owing to the Zeeman
effect.
Key: iin
Stokes I spectral cube, with axes in order Channel, X, Y.
Key: vin
Stokes V spectral cube, with axes in order Channel, X, Y.
Key: b
Output file name for Line-of-sight magnetic field.
Key: g
Output file name for amount of residual I found in V (FIT only)
Key: d
Output file name for the derivative of I/2 spectrum (DIV only)
Key: be
Output file name for the error in B (DIV only)
Key: blc
Bottom left corner of box to be fit
Key: trc
Top right corner of box to be fit
Key: freq
Frequency of line in GHz. This is used to determine amount of
splitting per Gauss.
Key: op
Operation code. Possible values are ``div'' and ``fit''. For
``div'', the line shift is determined by dividing V by the
derivative of I/2. For ``fit'', the line shift is determined
by fitting of the derivative of I and I to V.
Key: cutoff
For ``div'', the division will not be performed unless the
derivative of I/2 is greater than cutoff.
For ``fit'', the fit will not be performed unless one or more
channels in the I spectrum is larger in absolute
value than cutoff.
Key: vrms
RMS deviation in V spectrum in a signal free area. This can easily
be gotten using histo. Used for calculating error in B for op=div.
Key: mode
This determines the algorithms used, if operation=``fit''. It
can consist of several flags:
l Include leakage term.
2 Use 2 sided derivative approximation.
m Use maximum likelihood technique.
x Perform extra checks for better solutions, when
using the maximum likelihood technique.
Default mode=2m
Key: y corlen
Correlation length. Selected window must be divisible by this
number, which is the number of pixels over which you think the
magnetic field might be constant. Default is 1, try maybe 2 or 4.