|
|||
NRAO Home > CASA > CASA Task Reference Manual |
|
0.1.104 sdcal2old
Requires:
Synopsis
ASAP SD task [DEPRECATED]: calibration
Description
### DEPRECATION WARNING
#################################################
This task will be removed in CASA 5.1. The functionality of this task with
MeasurementSet format is replicated with sdcal.
#########################################################################
Task sdcal2old is an implementation of a calibration scheme like as interferometry, i.e., generate caltables and apply them. Available calibration modes are ’ps’, ’otf’, ’otfraster’, and ’tsys’. Those modes generates caltables for sky or Tsys calibration. Those caltables can be applied to the data by using calmode ’apply’.
The above three calibration modes, ’ps’, ’otf’, and ’otfraster’, generate sky calibration tables. The user should choose appropriate calibration mode depending on the data. Use case for each mode is as follows:
’ps’: position switch (including OTF) with explicit reference (OFF) spectra ’otf’: non-raster OTF scan without explicit OFFs (e.g. Lissajous, double circle, etc.) intends to calibrate fast scan data ’otfraster’: raster OTF scan without explicit OFFs
So, if the data contains explicit reference spectra, ’ps’ should be used. Otherwise, ’otfraster’ and ’otf’ are appropriate for raster OTF and non-raster OTF, respectively. In ’otf’ and ’otfraster’ modes, the task first try to find several integrations near edge as OFF spectra, then the data are calibrated using those OFFs. If the observing pattern is raster, you should use the ’otfraster’ mode to calibrate data. Otherwise, the ’otf’ mode should be used. For detail about edge marking, see inline help of sd.edgemarker module and its methods. Those modes are designed for OTF observations without explicit OFF spectra. However, these modes should work even if explicit reference spectra exist. In this case, these spectra will be ignored and spectra near edges detected by edge marker will be used as reference.
Except for how to choose OFFs, the procedure to derive calibrated spectra is common for the above three modes. Selected (or preset) OFF integrations are separated by its continuity in time domain, averaged in each segment, then interpolated to timestamps for ON integrations. Effectively, it means that OFF integrations are averaged by each OFF spectrum for ’ps’ mode, averaged by either ends of each raster row for ’otfraster’ mode, averaged by each temporal segments of detected edges for ’otf’ mode. The formula for calibrated spectrum is
Tsys * (ON - OFF) / OFF.
Arguments
Inputs |
| ||
infile |
| name of input SD dataset (must be in scantable format)
| |
| allowed: | string |
|
| Default: |
| |
calmode |
| SD calibration mode
| |
| allowed: | string |
|
| Default: | ps |
|
fraction |
| fraction of the OFF data to mark | |
| allowed: | any |
|
| Default: | variant 10% |
|
noff |
| number of the OFF data to mark | |
| allowed: | int |
|
| Default: | -1 | |
width |
| width of the pixel for edge detection
| |
| allowed: | double | |
| Default: | 0.5 |
|
elongated |
| whether observed area is elongated in one direction or
not | |
| allowed: | bool |
|
| Default: | False | |
tsysavg |
| Whether Tsys is averaged in spectral axis or not
| |
| allowed: | bool | |
| Default: | False |
|
tsysspw |
| list of IF IDs (spectral windows) and their channel
ranges of averaging for Tsys calibration.
| |
| allowed: | string |
|
| Default: |
|
|
applytable |
| (List of) sky and/or tsys tables
| |
| allowed: | any |
|
| Default: | variant
|
|
interp |
| Interpolation type in time[,freq]. Valid options are
”nearest”, ”linear”, ”cspline”, or any numeric string
that indicates an order of polynomial interpolation. You
can specify interpolation type for time and frequency
separately by joining two of the above options by comma
(e.g., ”linear,cspline”).
| |
| allowed: | string |
|
| Default: |
|
|
spwmap |
| A dictionary indicating IFNO combinations to apply
Tsys calibration to target. The key should be IFNO for
Tsys calibration and its associated value must be a list
of science IFNOs to be applied.
| |
| allowed: | any |
|
| Default: | variant |
|
field |
| select data by field IDs and names, e.g. ’3C2*’ (” = all)
| |
| allowed: | string |
|
| Default: |
|
|
spw |
| select data by IF IDs (spectral windows), e.g., ’3,5,7’ (”
= all)
| |
| allowed: | string |
|
| Default: |
|
|
scan |
| select data by scan numbers, e.g. ’21~23’ (”=all)
| |
| allowed: | string |
|
| Default: |
|
|
pol |
| select data by polarization IDs, e.g, ’0,1’ (” = all)
| |
| allowed: | string |
|
| Default: |
|
|
outfile |
| name of output file (See a WARNING in help)
| |
| allowed: | string |
|
| Default: |
|
|
overwrite |
| overwrite the output file if already exists
| |
| allowed: | bool |
|
| Default: | False |
|
void
Example
Keyword arguments:
infile -- Name of input SD dataset
calmode -- Calibration mode. If you want to generate calibration table
or apply existing calibration tables, set calmode to simple
string. On the other hand, if you want to calibrate data
on-the-fly, you have to set calmode to a composite calmode
string separated by comma. So far, sky calibration has three
types, ’ps’, ’otf’, and ’otfraster’. If observation is
configured to observe reference position, calmode must be
’ps’. Otherwise, ’otf’ or ’otfraster’ should be used
depending on observing pattern. If observing pattern is
raster scan, calmode must be ’otfraster’ while ’otf’ must
be used when observing pattern is non-raster
(e.g., Lissajous).
options: ’ps’,’otf’,’otfraster’,’tsys’,’apply’
default: ’ps’
example: Here is an example for composite calmode.
’ps,apply’ (do sky cal and apply)
’ps,tsys,apply’ (do sky and Tsys cal and apply)
>>> calmode expandable parameter
fraction -- Edge marker parameter of ’otf’ and ’otfraster’.
Specify a number of OFF integrations (at each
side of the raster rows in ’otfraster’ mode)
as a fraction of total number of integrations.
In ’otfraster’ mode, number of integrations
to be marked as OFF, n_off, is determined by
the following formula,
n_off = floor(fraction * n),
where n is number of integrations per raster
row. Note that n_off from both sides will be
marked as OFF so that twice of specified
fraction will be marked at most. For example,
if you specify fraction=’10%’, resultant
fraction of OFF integrations will be 20% at
most.
In ’otf’ mode, n_off is given by,
n_off = floor(fraction * n),
where n is number of total integrations.
n_off is used as criterion of iterative marking
process. Therefore, resulting total number of
OFFs will be larger than n_off. In practice,
fraction is a geometrical fraction of edge
region. Thus, if integrations are concentrated
on edge region (e.g. some of Lissajous
patterns), then resulting n_off may be
unexpectedly large.
default: ’10%’
options: ’20%’ in string style or float value less
than 1.0 (e.g. 0.15).
’auto’ is available only for ’otfraster’.
noff -- Edge marking parameter for ’otfraster’.
It is used to specify a number of OFF spectra near
edge directly. Value of noff comes before setting
by fraction. Note that n_off from both sides will
be marked as OFF so that twice of specified noff
will be marked at most.
default: -1 (use fraction)
options: any positive integer
width -- Edge marking parameter for ’otf’.
Pixel width with respect to a median spatial
separation between neighboring two data in time.
Default will be fine in most cases.
default: 0.5
options: float value
elongated -- Edge marking parameter for ’otf’.
Set True only if observed area is elongated
in one direction.
default: False
tsysavg -- Whether Tsys is averaged in spectral axis or not.
default: False
options: (bool) True, False
tsysspw -- list of IF IDs (spectral windows) and their channel
ranges of averaging for Tsys calibration.
It does no effect if you don’t want to do Tsys
calibration. the user is able to specify channel
range for averaging (effective if tsysavg is True).
default: ’’ (auto-detect tsys spws)
example: tsysspw=’3,5,7’ (IF IDs 3,5,7; all channels)
tsysspw=’<2’ (IF IDs less than 2; all channels)
tsysspw=’1:0~100’ (IF ID1; between channels 0 and 100)
applytable -- List of sky/Tsys calibration tables you want to
apply.
default: ’’
interp -- Interpolation method in time and frequency axis.
Set comma separated method strings if you want
to use different interpolation in time and
frequency.
options: ’linear’, ’cspline’, ’nearest’,
any numeric string indicating an order
of polynomial.
default: ’’ (linear in time and frequency)
example: ’linear,cspline’ (linear in time, cubic
spline in frequency)
’linear,3’ (linear in time, third order
polynomial in frequency)
’nearest’ (nearest in time and frequency)
spwmap -- Dictionary defining transfer of Tsys calibration.
Key must be IFNO for Tsys and its value must be
a list of IFNOs for science target.
default: {}
example: {1: [5,6], 3: [7,8]}
Tsys in IFNO1 is transferred to IFNO5, 6
while Tsys in IFNO3 is to IFNO7, 8.
field -- select data by field IDs and names
default: ’’ (use all fields)
example: field=’3C2*’ (all names starting with 3C2)
field=’0,4,5~7’ (field IDs 0,4,5,6,7)
field=’0,3C273’ (field ID 0 or field named 3C273)
this selection is in addition to the other selections to data
spw -- select data by IF IDs (spectral windows)
NOTE this task only supports IF ID selction and ignores channel
selection.
default: ’’ (use all IFs and channels)
example: spw=’3,5,7’ (IF IDs 3,5,7; all channels)
spw=’<2’ (IF IDs less than 2, i.e., 0,1; all channels)
spw=’30~45GHz’ (IF IDs with the center frequencies in range 30-45GHz; all channels)
this selection is in addition to the other selections to data
scan -- select data by scan numbers
default: ’’ (use all scans)
example: scan=’21~23’ (scan IDs 21,22,23)
this selection is in addition to the other selections to data
pol -- select data by polarization IDs
default: ’’ (use all polarizations)
example: pol=’0,1’ (polarization IDs 0,1)
this selection is in addition to the other selections to data
outfile -- Name of output file
NOTE if you omit, behavior of the task depends on calmode.
If calmode includes ’apply’, then omitting outfile indicates
that infile is overwritten by the calibrated data. In this case,
you have to set overwrite to True. If calmode doesn’t include
’apply’, omitting outfile indicates that the task will use
default outfile name based on infile and predefined suffix
(’_sky’ for sky, ’_tsys’ for Tsys).
default: ’’ (<infile>_<suffix> for calibration
while overwrite infile for apply mode)
overwrite -- overwrite the output file if already exists
options: (bool) True,False
default: False
NOTE this parameter is ignored when outform=’ASCII’
DESCRIPTION:
Task sdcal2old is an implementation of a calibration scheme like as
interferometry, i.e., generate caltables and apply them. Available
calibration modes are ’ps’, ’otf’, ’otfraster’, and ’tsys’. Those
modes generates caltables for sky or Tsys calibration. Those
caltables can be applied to the data by using calmode ’apply’.
The above three calibration modes, ’ps’, ’otf’, and ’otfraster’,
generate sky calibration tables. The user should choose
appropriate calibration mode depending on the data. Use case
for each mode is as follows:
’ps’: position switch (including OTF) with explicit
reference (OFF) spectra
’otf’: non-raster OTF scan without explicit OFFs
(e.g. Lissajous, double circle, etc.)
intends to calibrate fast scan data
’otfraster’: raster OTF scan without explicit OFFs
So, if the data contains explicit reference spectra, ’ps’ should
be used. Otherwise, ’otfraster’ and ’otf’ are appropriate for
raster OTF and non-raster OTF, respectively. In ’otf’ and
’otfraster’ modes, the task first try to find several integrations
near edge as OFF spectra, then the data are calibrated using those
OFFs. If the observing pattern is raster, you
should use the ’otfraster’ mode to calibrate data. Otherwise, the
’otf’ mode should be used. For detail about edge marking, see
inline help of sd.edgemarker module and its methods.
Those modes are designed for OTF observations without
explicit OFF spectra. However, these modes should work even if
explicit reference spectra exist. In this case, these spectra
will be ignored and spectra near edges detected by edge
marker will be used as reference.
Except for how to choose OFFs, the procedure to derive calibrated
spectra is common for the
above three modes. Selected (or preset) OFF integrations are
separated by its continuity in time domain, averaged in
each segment, then interpolated to timestamps for ON integrations.
Effectively, it means that OFF integrations are averaged by each
OFF spectrum for ’ps’ mode, averaged by either ends of each raster
row for ’otfraster’ mode, averaged by each temporal segments of
detected edges for ’otf’ mode. The formula for calibrated spectrum
is
Tsys * (ON - OFF) / OFF.
You can calibrate data on-the-fly like sdcal task by setting
calmode to a composite calmode string separated by comma.
For example, calmode=’ps,apply’ means doing sky calibration and
apply it on-the-fly. In this case, caltable is generated as a
temporary plain table and will be deleted at the end.
Allowed calibration modes in this task is as follows:
ps
generate sky caltable using ’ps’ mode
otf
generate sky caltable using ’otf’ mode
otfraster
generate sky caltable using ’otfraster’ mode
tsys
generate tsys caltable
apply
apply caltables specified by applytable parameter
ps,apply
generate temporary sky caltable using ’ps’ mode and
apply it. also apply caltables specified by applytable
ps,tsys,apply
generate temporary sky caltable using ’ps’ mode as well
as temporary tsys caltable, and apply them.
otf,apply
generate temporary sky caltable using ’otf’ mode and
apply it. also apply caltables specified by applytable
otf,tsys,apply
generate temporary sky caltable using ’otf’ mode as well
as temporary tsys caltable, and apply them.
otfraster,apply
generate temporary sky caltable using ’otfraster’ mode
and apply it. also apply caltables specified by applytable
otfraster,tsys,apply
generate temporary sky caltable using ’otfraster’ mode
as well as temporary tsys caltable, and apply them.
There are several control parameters for sky/Tsys calibration and
application of caltables. See the above parameter description.
In ALMA, Tsys measurement is usually done using different spectral
setup from spectral windows for science target. In this case, sdcal2old
transfers Tsys values to science spectral windows in the application
stage. To do that, the user has to give a list of spectral windows for
Tsys measurement as well as mapping between spectral windows for Tsys
measurement and scicence target. These can be specified by parameters
’tsysspw’ and ’spwmap’, which are defined as subparameters of ’calmode’.
For example, suppose that Tsys measurements for science windows 17, 19,
21, and 23 are done in spw 9, 11, 13, and 15, respectively.
In this case, tsysspw and spwmap should be specified as follows:
tsysspw = ’9,11,13,15’
spwmap = {9:[17],11:[19],13:[21],15:[23]}
Below is an example of full specification of task parameters for calmode
of ’ps,tsys,apply’:
default(sdcal2old)
infile = ’foo.asap’
calmode = ’ps,tsys,apply’
spw = ’’
tsysspw = ’9,11,13,15’
spwmap = {9:[17],11:[19],13:[21],15:[23]}
outfile = ’bar.asap’
sdcal2old()
Note that, in contrast to applycal task, spwmap must be a dictionary
with Tsys spectral window as key and a list of corresponding science
spectral window as value. Note also that the parameter ’spw’ should
not be used to specify a list of spectral windows for Tsys measurement.
It is intended to select data to be calibrated so that the list should
contain spectral windows for both science target and Tsys measurement.
The task will fail if you use ’spw’ instead of ’tsysspw’.
For Tsys calibration, the user is able to choose whether Tsys is
averaged in spectral axis or not. If tsysavg is False (default),
resulting Tsys is spectral value. On the other hand, when tsysavg
is True, Tsys is averaged in spectral axis before output. The channel
range for averaging is whole channels by default. If channel range is
specified by tsysspw string, it is used for averaging. The user can
specify channel range with ms selection syntax. For example,
tsysspw = ’1:0~100’
specifies spw 1 for Tsys calibration and channel range between channel
0 and 100 for averaging. You can specify more than one ranges per spw.
tsysspw = ’1:0~100;200~400’
In this case, selected ranges are between 0 and 100 plus 200 and 400.
Note that even if multiple ranges are selected, the task average whole
ranges together and output single averaged value. You can specify multiple
spws by separating comma.
tsysspw = ’1:0~100,3:400~500’
Note that specified channel range is ignored if tsysavg is False.
More information about CASA may be found at the
CASA web page
Copyright © 2016 Associated Universities Inc., Washington, D.C.
This code is available under the terms of the GNU General Public Lincense
Home |
Contact Us |
Directories |
Site Map |
Help |
Privacy Policy |
Search