importasdm – Convert an ALMA Science Data Model observation into a CASA visibility file (MS) – import/export task

Description

Convert an ALMA Science Data Model observation into a CASA visibility file (MS)

Parameters

Title

Parameter	Default	Description
asdm	''	Name of input asdm directory (on disk)
vis	''	Root name of the ms to be created. Note the .ms is NOT added
createmms	False	Create a Multi-MS output
separationaxis	'auto'	Axis to do parallelization across (scan, spw, baseline, auto)
numsubms	'auto'	The number of SubMSs to create (auto or any number)
corr_mode	'all'	Specifies the correlation mode to be considered on input. A quoted string containing a sequence of ao, co, ac,or all separated by whitespaces is expected
srt	'all'	Specifies the spectral resolution type to be considered on input. A quoted string containing a sequence of fr, ca, bw, or all separated by whitespaces is expected
time_sampling	'all'	Specifies the time sampling (INTEGRATION and/or SUBINTEGRATION) to be considered on input. A quoted string containing a sequence of i, si, or all separated by whitespaces is expected
ocorr_mode	'ca'	Output data for correlation mode AUTO_ONLY (ao) or CROSS_ONLY (co) or CROSS_AND_AUTO (ca)
compression	False	Flag for turning on data compression
lazy	False	Make the MS DATA column read the ASDM Binary data directly (faster import, smaller MS)
asis	''	Creates verbatim copies of the ASDMtables in the ouput measurement set. Value given must be a string of table names separated by spaces; A * wildcard is allowed.
wvr_corrected_data	'no'	Specifies which values are considerd in the SDM binary data to fill the DATA column in the MAIN table of the MS; yes for corrected, no for uncorrected, both for corrected and uncorrected (resulting in two MSs)
scans	''	Processes only the specified scans. A scan specification consists in an exec bock index followed by the : character, followed by a comma separated list of scan indexes or scan index ranges. (e.g. 0:1;1:2~6,8;2:,3:24~30)
ignore_time	False	All the rows of the tables Feed, History, Pointing, Source, SysCal, CalDevice, SysPower, and Weather are processed independently of the time range of the selected exec block / scan.
process_syspower	True	Process the SysPower table?
process_caldevice	True	Process the CalDevice table?
process_pointing	True	Process the Pointing table?
process_flags	True	Create online flags in the FLAG_CMD sub-table?
tbuff	float(0.0)	Time padding buffer (seconds)
applyflags	False	Apply the flags to the MS.
savecmds	False	Save flag commands to an ASCII file
outfile	''	Name of ASCII file to save flag commands
flagbackup	True	Back up flag column before applying flags.
verbose	False	Output lots of information while the filler is working
overwrite	False	Over write an existing MS(s)
showversion	False	Report the version of asdm2MS being used
useversion	'v3'	Version of asdm2MS to be used (v3 default, should work for all data)
bdfflags	False	Set the MS FLAG column according to the ASDM _binary_ flags
with_pointing_correction	False	Add (ASDM::Pointing::encoder - ASDM::Pointing::pointingDirection) to the value to be written in MS::Pointing::direction
remove_ref_undef	False	If set to True then apply fixspwbackport on the resulting MS(es).
convert_ephem2geo	True	if True, convert any attached ephemerides to the GEO reference frame (time-spacing not changed)
polyephem_tabtimestep	float(0.)	Timestep (days) for the tabulation of polynomial ephemerides. A value <= 0 disables tabulation.

Parameter Explanations

asdm

''

Name of input ASDM file (directory)

Default: none

Example: asdm=’ExecBlock3’

vis

''

Root ms name.

Default: none

Note that a prefix (.ms) is NOT appended to this name.

createmms

False

Create a Multi-MS partitioned according to the given separation axis.

Default: False Options: False|True

For more detailed documentation on partition, Multi-MS and the MPI use in CASA, please see CASA Docs (https://casa.nrao.edu/casadocs/).

separationaxis

'auto'

Axis to do parallelization across

Default: ‘auto’ Options: ‘scan’, ‘spw’, ‘baseline’, ‘auto’

• auto: will partition per scan/spw to obtain optimal load balancing with the following criteria: 1 - Maximize the scan/spw/field distribution across sub-MSs 2 - Generate sub-MSs with similar size

• ‘scan’ or ‘spw’: will partition the MS into scan or spw. The individual sub-MSs may not be balanced with respect to the number of rows.

• ‘baseline’: mostly useful for Single-Dish data. This axis will partition the MS based on the available baselines. If the user wants only auto-correlations, use the ocorr_mode=’ao’. Note that if numsubms=’auto’, partition will try to create as many subMSs as the number of available servers in the cluster. If the user wants to have one subMS for each baseline, set the numsubms parameter to a number higher than the number of baselines to achieve this.

numsubms

'auto'

The number of sub-MSs to create in the Multi-Ms.

Default: ‘auto’ Options: any integer number (example: numsubms=4)

The default ‘auto’ is to partition using the number of available servers given when launching CASA. If the task is unable to determine the number of running servers, or the user did not start CASA using mpicasa, numsubms will use 8 as the default.

Example: Launch CASA with 5 engines, where 4 of them will be used to create the MMS (the first engine is used as the MPIClient): mpicasa -n 5 casa –nogui –log2term CASA> importasdm(‘uid__A1’, createmms=True)

corr_mode

'all'

Correlation mode to be considered on input.

Default: ‘all’ Options: ao, co, ac, or all

srt

'all'

Spectral resolution type.

Default: ‘all’ Options: fr, ca, bw, or all

time_sampling

'all'

Specifies the time sampling (INTEGRATION and/or SUBINTEGRATION) to be considered on input.

Default: ‘all’ Options: i, si, or all

A quoted string containing a sequence of i, si, or all separated by whitespaces is expected

ocorr_mode

'ca'

Output data for correlation mode AUTO_ONLY (ao) or CROSS_ONLY (co) or CROSS_AND_AUTO (ca)

Default: ‘ca’ Options: ao, co, ca

compression

False

Produce compressed columns in the resulting measurement set.

Default: False Options: False|True

lazy

False

Make the MS DATA column read the ASDM Binary data directly (faster import, smaller MS).

Default: False Options: False|True

Instead of writing a copy of the visibilities into a standard DATA column, lazy=True will make importasdm only write a lookup-table such that later access to the DATA column will read the ASDM binary visibility data directly. This requires that the ASDM not be removed from its location as long the the DATA column is needed. Use method ms.asdmref() to query and manipulate the reference to the ASDM.

lazy=True will save ca. 50% disk space and accelerate the DATA column access by ca. 10%. lazy=True will only work when there is visibility data in the ASDM, not with pure radiometer data.

asis

''

Creates verbatim copies of the ASDM tables in the output measurement set.

Default: none

The value given to this option must be a list of table names separated by space characters; the wildcard character ‘*’ is allowed in table names.

wvr_corrected_data

'no'

Specifies which values are considerd in the ASDM binary data to fill the DATA column in the MAIN table of the MS.

Default: no Options: no|yes|both

• no: uncorrected data

• yes: corrected data

• both: for corrected and uncorrected data. Note if both is selected, two measurement sets are created, one with uncorrected data and the other with corrected data (which name is suffixed by ‘-wvr-corrected’)

scans

''

Processes only the scans specified in the option’s value.

Default: none (all scans)

This value is a semicolon separated list of scan specifications. A scan specification consists in an exec bock index followed by the character ‘:’ followed by a comma separated list of scan indexes or scan index ranges. A scan index is relative to the exec block it belongs to. Scan indexes are 1-based while exec blocks’s are 0-based.

Examples: ‘0:1’ ‘2:2~6’ ‘0:1;1:2~6,8;2:,3:24~30’ ‘1,2’ ‘3:’ alone will be interpreted as ‘all the scans of the exec block#3’. An scan index or a scan index range not preceded by an exec block index will be interpreted as ‘all the scans with such indexes in all the exec blocks’.

ignore_time

False

All the rows of the tables Feed, History, Pointing, Source, SysCal, CalDevice, SysPower, and Weather are processed independently of the time range of the selected exec block / scan.

Default: False Options: False|True

process_syspower

True

The SysPower table is processed if and only if this

parameter is set to true.

Default: True Options: True|False

process_caldevice

True

The CalDevice table is processed if and only if this parameter is set to true.

Default: True Options: True|False

process_pointing

True

The Pointing table is processed if and only if this parameter is set to true.

Default: True Options: True|False

If set to False, the POINTING table is empty in the resulting MS

process_flags

True

Create online flags based on the Flag.xml, Antenna.xml and SpectralWindow.xml files and copy them to the FLAG_CMD sub-table of the MS.

Default: True Options: True|False

The flags will NOT be applied unless the parameter applyflags is set to True. Optionally, the flags can also be saved to an external ASCII file if savecmds is set to True.

tbuff

float(0.0)

Time padding buffer (seconds)

Subparameter of process_flags=True Default: 0.0

NOTE: this time is in seconds. You should currently set the value of tbuff to be 1.5x the correlator integration time if greater than 1 second. For example, if the SDM has integrations of 3 seconds, set tbuff=4.5. Likewise, set tbuff=15.0 for 10-sec integrations.

applyflags

False

Apply the online flags to the MS.

Subparameter of process_flags=True Default: False Options: False|True

savecmds

False

Save the flag commands to an ASCII file given by the parameter outfile.

Subparameter of process_flags=True Default: False Options: False|True

outfile

''

Filename or list of filenames where to save the online flag commands.

Subparameter of process_flags=True Default: ‘’ (it will save on a filename composed from the MS name(s).) E.g., for vis=’uid_A02.ms’, the outfile will be ‘uid_A02_cmd.txt’.

flagbackup

True

Back up flag column before applying flags.

Default: True Options: True|False

verbose

False

Produce log output as asdm2MS is being run

Default: False Options: False|True

overwrite

False

Over write an existing MS(s) or MS(s), if the option wvr_corrected_data=’both’

Default: False (do not overwrite) Options: False|True

NOTE: the overwrite parameter affects all the output of the task. If any of the following exist, it will not overwrite them. MS(s), .flagversions, online flag files. When set to True, it will overwrite the MS, .flagversions and online flag file.

showversion

False

Report the version of asdm2MS being used

Default: False Options: False|True

useversion

'v3'

Version of asdm2MS to be used

Default: ‘v3’ (should work for all data)

bdfflags

False

Set the MS FLAG column according to the ASDM _binary_ flags

Default: False Options: False|True

with_pointing_correction

False

Add (ASDM::Pointing::encoder - ASDM::Pointing::pointingDirection) to the value to be written in MS::Pointing::direction

Default: False Options: False|True

remove_ref_undef

False

If set to True then apply fixspwbackport on the resulting MS(es).

Default: False Options: False|True

convert_ephem2geo

True

if True, convert any attached ephemerides to the GEO reference frame (time-spacing not changed)

Default: True Options: True|False

ALMA uses ephemerides with observer location equal to the ALMA site. For later processing of the radial velocity information in, e.g. cvel, a geocentric ephemeris is needed. Setting this option to True will perform the conversion of positions and velocities on all attached ephemerides in the imported MS. This will neither change the time-spacing nor the duration of the ephemeris. No interpolation in time is done.

polyephem_tabtimestep

float(0.)

Timestep (days) for the tabulation of polynomial ephemerides. A value less than or equal to 0 disables tabulation.

Default: 0

Presently, VLA data can contain polynomial ephemerides. ALMA data uses tabulated values.