calibrater.setapply - Function
2.2.1 Arrange to apply calibration
Description
This function is used to specify the calibration components which should be
applied during subsequent execution of the solve and correct functions. This
function should be executed as many times as necessary to specify all desired
calibration components.
Each calibration component represents a separate calibration matrix correction
included in the measurement equation. The different types correspond to
different instrumental and atmospheric effects. Calibration components are
available as calibration tables generated by previous solve executions (types
’B’,’BPOLY’,’G’,’GSPLINE’, ’D’,’DF’,’T’,’M’,’MF’,’X’), or are calculated
analytically on the fly (types ’P’, ’TOPAC’, ’GAINCURVE’). Upon execution
of solve or correct, the group of specified calibration components will be
applied in the order prescribed by the Measurement Equation formalism.
The parameters are as follows:
-
type
-
The
calibration
type
being
specified.
This
is
only
required
for
analytic
types
(’P’,’TOPAC’,’GAINCURVE’).
When
specifying
an
existing
pre-solved
calibration
table,
it
is
not
necessary
to
explicitly
specify
the
type;
this
will
be
discerned
from
the
table.
(Specifying
the
type
as
well
as
the
table
will
force
a
check
that
the
table
contains
solutions
of
the
specified
type.
For
type=’GAINCURVE’,
an
elevation-dependent
correction
will
be
applied
using
parameters
read
from
the
data
repository.
Currently,
this
is
only
supported
for
the
VLA.
-
t
-
This
parameter
will
be
used
in
a
future
release
to
control
the
range
of
applicability
of
the
specified
calibration.
Currently,
it
is
ignored.
-
table
-
For
pre-solved
calibration,
the
file
name
of
the
table
to
apply.
-
field
-
The
fields
to
select
from
the
specified
table,
using
MS
Selection
syntax
(as
in
selectvis).
-
interp
-
The
desired
type
of
time-dependent
interpolation.
Use
interp=’nearest’
to
calibrate
each
datum
with
the
calibration
value
nearest
in
time.
Use
interp=’linear’
to
calibrate
each
datum
with
calibration
phases
and
amplitudes
linearly
interpolated
from
neighboring
(in
time)
values.
In
the
case
of
phase,
this
mode
will
assume
that
phase
jumps
greater
than
180
degrees
between
neighboring
points
indicate
a
cycle
slip,
and
the
interpolated
value
will
follow
this
change
in
cycle
accordingly
(i.e.,
the
implied
rate
will
always
be
less
than
180
degrees
per
sample).
Use
interp=’aipslin’
to
emulate
the
basic
interpolation
mode
used
in
classic
AIPS,
i.e.,
linearly
interpolated
amplitudes,
with
phases
derived
from
linear
interpolation
of
the
complex
calibration
values.
While
this
method
avoids
having
to
track
cycle
slips
(which
is
unstable
for
solutions
with
very
low
SNR),
it
will
yield
a
phase
interpolation
which
becomes
increasingly
non-linear
as
the
spanned
phase
difference
increases.
The
non-linearity
mimics
the
behavior
of
interp=’nearest’
as
the
spanned
phase
difference
approaches
180
degrees
(the
phase
of
the
interpolated
complex
calibration
value
initially
changes
very
slowly,
then
rapidly
jumps
to
the
second
value
at
the
midpoint
of
the
interval).
If
the
uncalibrated
phase
is
changing
this
rapidly,
a
’nearest’
interpolation
is
not
desirable.
Usually,
interp=’linear’
is
the
best
choice.
The
interp
parameter
is
applicable
to
any
calibration
type,
as
long
as
there
are
sufficient
solutions
available
to
perform
the
interpolation.
Note
that
calibration
solutions
which
have
been
determined
for
only
one
timestamp
will
default
to
’nearest’.
More
interpolation
options
(e.g.,
’cubic’)
will
be
added
in
the
future.
-
select
-
Used
to
specify
general
selection
of
a
subset
of
calibration
measurements
from
the
table
to
be
applied
to
the
visibility
data.
Arbitrary
cross-calibration
is
possible
by
combining
this
function
with
the
setdata
function.
The
string
specified
must
be
a
valid
TaQL
expression.
-
spwmap
-
This
parameter
is
used
to
indicate
how
solutions
derived
from
different
spectral
windows
should
be
applied
to
other
spectral
windows.
Nominally,
data
in
each
spectral
window
will
be
corrected
by
solutions
derived
from
the
same
spectral
window.
This
is
the
default
behavior
of
spwmap,
i.e.,
if
spwmap
is
not
specified,
calibrater
will
insist
that
data
be
corrected
by
solutions
from
the
same
spw.
Otherwise,
spwmap
takes
a
vector
of
integers
indicating
which
spectral
window
solutions
to
apply
to
which
spectral
window
data,
such
that
spwmap[j]=i
causes
solutions
derived
from
the
i-th
spectral
window
to
be
used
to
correct
the
j-th
spectral
window.
For
example,
if
(say)
bandpass
solutions
are
available
for
spws
0
&
2,
and
it
is
desired
that
these
be
applied
to
spws
1
&
3
(as
well
as
0
&
2),
respectively,
use
spwmap=[0,0,2,2].
Even
if
some
spws
do
not
require
an
explicit
spwmap
setting,
yet
one
or
more
does,
it
is
safest
to
specify
it
explicitly
for
all,
e.g.,
spwmap=[0,1,3,3]
indicates
that
spw
2
will
be
corrected
with
solutions
from
spw
3,
and
the
others
will
behave
nominally.
Note
that
if
no
solutions
exist
for
any
of
the
spws
specified
in
spwmap,
an
error
message
will
result.
-
calwt
-
If
set
True,
the
data
weights
will
be
calibrated
along
with
the
data.
This
is
usually
desirable.
-
opacity
-
For
type=’TOPAC’,
an
elevation-dependent
opacity
correction
will
be
applied
according
to
the
zenith
opacity
value
supplied
in
the
opacity
parameter.
Currently,
only
one
zenith
opacity
value
can
be
supplied,
and
it
is
used
for
all
antennas.
Use the state function to review the list of calibration components that have been
set for application.
Pending improvements:
-
Enable
variety
of
interpolation
modes
and
timescales
-
Allow
for
antenna-
and
time-dependent
opacities
Arguments
|
|
|
|
| Inputs | |
|
| type | | Component type
|
| | | allowed: | string |
| | | Default: | B BPOLY G GSPLINE D P T TOPAC
GAINCURVE |
| t | | Interpolation interval (seconds)
|
| | | allowed: | double |
| | | Default: | 0.0 |
| table | | Calibration table name |
| | | allowed: | string |
| | | Default: | |
| field | | Select on field
|
| | | allowed: | any |
| | | Default: | variant |
| interp | | Interpolation type (in time)
|
| | | allowed: | string |
| | | Default: | aipslin nearest linear |
| select | | TAQL selection string. Default is no selection.
|
| | | allowed: | string |
| | | Default: | |
| calwt | | Calibrate weights?
|
| | | allowed: | bool |
| | | Default: | false |
| spwmap | | Spectral windows to apply
|
| | | allowed: | intArray |
| | | Default: | -1 |
| opacity | | Array-wide zenith opacity (for type=’TOPAC’)
|
| | | allowed: | double |
| | | Default: | 0.0 |
| |
Returns
bool
Example
cb.open(’ngc5921.ms’)
cb.selectvis(field=’N5921*’)
cb.setapply (type=’G’, table=’gcal’, field=’1445*’)
cb.setapply (type=’P’)
cb.correct();
cb.close();
In this example, we apply parallactic angle corrections and a gain calibration derived
from a field whose name matches ’1445*’ in a caltable called ’gcal’ to data for a field
matching ’N5921*’
Please send any comments or questions about CASA or AIPS++
to aips2-requests@nrao.edu
Copyright © 2008 Associated Universities Inc.,
Washington, D.C.
This code is available under the terms of the GNU General Public Lincense
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Updated daily during alpha development.
