Search for Spectral Line Rest Frequencies (slsearch)

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6.14 Search for Spectral Line Rest Frequencies (slsearch)

The slsearch task allows the spectral line enthusiast to find their favorite spectral lines in subset of the Splatalogue spectral line catalog (ttp://www.splatalogue.net})wich is distributed with CASA. In addition, one can export custom catalogs from Splatalogue and import them to CASA using the task splattotable (Sect. 6.15) or tool method sl.splattotable(). One can even import catalogs with lines not in Splatalogue using the same file format.

The inputs to slsearch are as follows:

#  slsearch :: Search a spectral line table.
tablename           =         ’’        #  Input spectral line table name to
                                        #   search. If not specified, use the
                                        #   default table in the system.
outfile             =         ’’        #  Results table name. Blank means do not
                                        #   write the table to disk.
freqrange           =   [84, 90]        #  Frequency range in GHz.
species             =       [’’]        #  Species to search for.
reconly             =      False        #  List only NRAO recommended
                                        #   frequencies.
chemnames           =       [’’]        #  Chemical names to search for.
qns                 =       [’’]        #  Resolved quantum numbers to search
                                        #   for.
rrlinclude          =       True        #  Include RRLs in the result set?
rrlonly             =      False        #  Include only RRLs in the result set?
     intensity      =         -1        #  CDMS/JPL intensity range. -1 -> do not
                                        #   use an intensity range.
     smu2           =         -1        #  S*mu*mu range in Debye**2. -1 -> do
                                        #   not use an S*mu*mu range.
     loga           =         -1        #  log(A) (Einstein coefficient) range.
                                        #   -1 -> do not use a loga range.
     eu             =         -1        #  Upper energy state range in Kelvin. -1
                                        #   -> do not use an eu range.
     el             =         -1        #  Lower energy state range in Kelvin. -1
                                        #   -> do not use an el range.

verbose             =       True        #  List result set to logger (and
                                        #   optionally logfile)?
     logfile        =         ’’        #  List result set to this logfile (only
                                        #   used if verbose=True).
     append         =       True        #  If true, append to logfile if it
                                        #   already exists, if false overwrite
                                        #   logfile it it exists. Only used if
                                        #   verbose=True and logfile not blank.

wantreturn          =       True        #  If true, return the spectralline tool
                                        #   associated with the result set.
async               =      False        #  If true the taskname must be started

The table is provided in the tablename parameter but if it is blank (the default), the catalog which is included with CASA will be used. Searches can be made in a parameter space with large dimensionality:

freqrange Frequency range in GHz.
species Species to search for.
reconly List only NRAO recommended frequencies.
chemnames Chemical names to search for.
qns Resolved quantum numbers to search for.
intensity CDMS/JPL intensity range.
smu2 Sμ² range in Debye².
loga log(A) (Einstein coefficient) range.
el Lower energy state range in Kelvin.
eu Upper energy state range in Kelvin.
rrlinclude Include RRLs in the result set?
rrlonly Include only RRLs in the result set?

Notation is as found in the Splatalogue catalog.

Example:
Search for all lines of the species HOCN and HOCO+ in the 200-300GHz range:

slsearch(outfile="myresults.tbl", freqrange = [200,300], species=[’HOCN’, ’HOCO+’])

The task can also return a pythin dictionary if assigned a variable like:

myLines = slsearch(outfile="myresults.tbl", freqrange = [200,300], species=[’HOCN’, ’HOCO+’])

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