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CASA Toolkit

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Full functionality of CASA; more challenging interface - See User Ref ... VGEO/VTOP: Cometary table. Lines: Small line list. geodetic: IERS. IGRF. IMF. KpApF107 ... – PowerPoint PPT presentation

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Title: CASA Toolkit


1
CASA Toolkit
  • ( originally prepared by J. McMullin)

2
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.

3
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

4
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

5
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

6
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

7
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

8
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

9
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

10
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)

11
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

12
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

13
ATF Example Use
  • encoder output review
  • PSI monitoring data review
  • Correlator dump (pre-ASDM) review

14
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.

15
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

16
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
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