CASA Toolkit

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CASA Toolkit

• ( originally prepared by J. McMullin)

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Toolkit

• Full functionality of CASA more challenging
  interface - See User Ref Man
• tools are functions
• call from casapy as lttoolgt.ltmethodgt()
• default tool objects are pre-constructed
• e.g. imager (im) , calibrater (cb), ms (ms) ,
  etc. (see toolhelp)
• Must always tool.open/tool.close !!
• No globals must specify parameter if you want to
  over-ride the default.
• tool help (startup, toolhelp for full listing)
• help toolname - provides one line help for all of
  the tool methods
• toolname.ltTABgt - lists all of the method names
  ignore any __name__ - these are for internal use.
• toolname.method? - gives short help and parameter
  list with defaults.

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Tools covered

• Discuss several tools not covered by talks
• qa - quantities with unit information
• me - measures (quantities with frame information)
• tb - manipulation of tables (underlying data
  structure in CASA is the table)
• pl - pylab Python library mathematical utilities
  and plotting
• cs/ia - coordinate system utilities

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qa (Quanta) http//casa.nrao.edu/docs/casaref/qua
nta-Module.htmlx284-2860001.4

• create quantities with units
• qa.quantity
• qa.map,qa.maprec - list known units/constants
• qa.constant - get a known constant
• qa.getvalue, getunit - get bits of a quantity
• perform unit conversions
• convert, tos, totime, toangle
• formatting of units (e.g., time, angle)
• formxxx
• math (add, subtract, etc) values with units
• add, sub, mul, div, trig fns, pow, exp, log,
  sqrt, etc
• compare quantities
• compare, le, lt, eq, ne, gt, ge, ceil, floor,
  check, checkfreq, isangle

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me (Measures) http//casa.nrao.edu/docs/casaref/m
easures-Module.htmlx235-2360001.3

• measure quantity with a specified reference
  frame (e.g., UTC, J2000, mars) known measures
  are
• epoch instance in time (expressed as MJD)
• direction direction towards an astronomical
  object
• frequency electromagnetic wave
• radialvelocity radial velocity of astronomical
  object
• baseline interferometer baseline
• uvw UVW coordinates
• earthmagnetic Earths magnetic field

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me (Measures)

• conversion - convert a measure between frames
  (e.g., UTC to LAST)
• Calculation - calculate a measure (e.g., rest
  frequency from a velocity and a frequency)
• Create a measure
• me.epoch()
• me.direction()
• me.position()
• me.doppler
• me.frequency
• me.baseline
• me.uvw

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me (Measures)

• Information
• me.obslist() - list of observatories
• me.observatory(observatory_name) - measure
  (position) of observatory
• me.sourcelist() - list of known sources
• me.source(name) - measure of source
• me.linelist() - (very short) spectral line list
• me.spectralline(line) - measure of line
• me.listcodes() - list known reference codes

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me (Measures)

• Conversion
• me.measure - convert between reference frames
• me.toradialvelocity, me.tofrequency,
  me.todoppler, me.torestfrequency, me.touvw
• Calculate
• me.separation, me.posangle, me.rise, me.riseset
• Access
• me.getvalue, me.gettype, m.getref, me.getoffset

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tb - tables http//casa.nrao.edu/docs/casaref/tab
le-Tool.htmlx618-6330003.2.1

• create, manipulate tables (Note the
  MeasurementSet is a set of tables!)
• view - tb.browse (spreadsheet view)
• information
• summary, name, colnames, ncols, nrows,
  colkeywordnames, fieldnames, keywordnames
• manipulate
• get cell, cellslice, col, varcol, colslice,
  keyword, keywords, desc
• put cell, cellslice, col,varcol, colslice,
  keyword, keywords
• addrows, removerows, addcols, removecols
• flush - write contents to disk

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tb - tables

• Import
• tb.fromfits - create table from binary FITS
• tb.fromASDM - create table from ASDM
• tb.fromascii - create table from ASCII format
• specify separator
• specify headerfile/autoheader
• Data types R (Real), D (Double), X (Complex
  real,imaginary), Z (Complex amp,phase), A
  (ASCII), B (Boolean), I (Integer)

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tb - tables

• get/put methods cell, cellslice, col, coldesc,
  colkeyword, colkeywords, colslice, desc, keyword,
  keywords
• info colnames, colkeywordnames, datachanged,
  fieldnames, keywordnames, name, ncols, nrows,
  rownumbers, summary
• edit addcols, addreadmeline, addrows,
  removecols, removerows, renamecol
• browse spreadsheet view of the table

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pl - pylab http//matplotlib.sourceforge.net/

• pylab(Matplotlib) functions
• http//matplotlib.sourceforge.net/ - lots of good
  examples (see Screenshots).
• Combined with the tb tool allows complete data
  access and exploration.
• Math e.g., conjugate, convolve, fft, hanning,
  etc
• Plotting e.g., axhline, annotate, plot, etc

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ATF Example Use

• encoder output review
• PSI monitoring data review
• Correlator dump (pre-ASDM) review

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cs - Coordinate Systems http//casa.nrao.edu/docs/
casaref/coordsys-Tool.htmlx122-1220001.1.3

• store and manipulate a coordinate system (a set
  of coordinates (e.g., direction (RA/DEC),
  spectral (LSRK frequency), etc).
• handles both pixel and world coordinates
• Contains additional information, e.g., telescope,
  date of observation, etc.

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cs - Coordinate Systems

• get/set
• telescope, observer, epoch, referencecode,
  restfrequency, increment, referencepixel,
  referencelocation, referencevalue, names, units,
  projection
• settelescope, setobserver, setepoch,
  setreferencecode, setrestfrequency, setincrement,
  setreferencepixel, setsetreferencelocation,
  setreferencevalue, setnames, setunits,
  setprojection, setreferencecode, setprojection
• conversion
• convert, velocitytofrequency, etc
• utility
• summary, axiscoordinatetypes, naxes

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Data Repository

• Comes with CASA installation
• catalogs
• JPL line list
• ephemerides
• DE200/405 Positions of the planets, sun, moon,
  nutations, librations
• Sources Bright radio sources
• VGEO/VTOP Cometary table
• Lines Small line list
• geodetic
• IERS
• IGRF
• IMF
• KpApF107
• Observatories
• TAI_UTC
• nrao
• CalModels
• GainCurves