1 Language WEEDS\ Package to analyze spectral surveys Weeds is a CLASS extension to analyze spectral surveys or spectral lines observations with large bandwidths. It provides several commands to identify lines on a spectrum and to model it. Available commands: LID Identify lines on the current spectra LFIND Find lines from a species within a frequency range LLIST List lines from the line index LGET Get a line from the line index LPLOT Plot a line from the current line index MODSOURCE Model the emission of a source at the LTE MODSHOW Show the results of MODSOURCE For more information of each command, type 'help ' 1 LFIND [WEEDS\]LFIND [SPECIES [FMIN FMAX]] [/SORTBY ORDER] [/ENERGY ENERGY] [/AIJ AMIN] Find the lines within a frequency range and create a line index. The command looks for the lines between FMIN and FMAX in the database se- lected with the USE IN command. If not specified, the values of FMIN and FMAX are taken from the current spectra. Arguments: SPECIES the name of the species. Default is "All". FMIN the minimum frequency in MHz. FMAX the maximum frequency in MHz Options: /SORTBY sort the lines according to ORDER, which can be any combi- nation of "frequency", "energy" and "aeinstein", and all the subsequent permutations. /ENERGY refine the search to lines with upper level energy lower than ENERGY, expressed in Kelvins. /AIJ refine the search to lines with einstein A coefficient greater than AMIN, expressed s-1. 1 LGET [WEEDS\]LGET [LINEINDEX] [/INDEX] Get a line from the line index. The commands checks if the line frequen- cy is covered by the current scan. If yes, the scan frequency is modi- fied so that the rest frequency corresponds to the line frequency. The command works in a similar fashion than GET: for example LGET F will get the first line in the line list, LGET N will get the next one, etc. It is especially useful when one want to search for lines of a given species. For example, one can list all methanol lines in the 3 mm band, ordered by increasing upper level energy, with: LAS> LLIST "CH3OH, vt=0,1" 80000 110000 /SORTBY e and then examine each of the line candidates with: LAS> LGET F LAS> LPLOT LAS> LGET N LAS> LPLOT LAS> ... Options: /INDEX search for the line in all scans of the scan index. If this option is set, LGET begins by searching for the first scan in scan index (from the last FIND command) that cov- ers the line frequency. It is useful when working with line surveys that consists in several scans, each covering a different frequency band. Arguments: LINEINDEX the line index. It can be either: 1) One of the following letters: "f" get the first line of the index "l" get the last line of the index "p" get the previous line in the index "n" get the next line of the index 2) An integer 1 LID [WEEDS\]LID [/SPECIES Name1 Name2 ...] [/ENERGY ENERGY] [/AIJ AMIN] [[/DELTA DFREQ] | [/FULL]] [/IMAGE] [/LOOP] Search for lines in the database around a central frequency and mark them on the current spectra. By default, the central frequency is se- lected with the mouse left button. The search is done in an interval of width DFREQ around the selected frequency; alternatively, the /FULL op- tion may be used to search for lines over the entire frequency range covered by the current spectra. The line database in which the search is performed may be selected with the USE IN command. Options: /SPECIES refine the search to lines of one or more species. The species name should match exactly that in the database. Wildcards '*' are accepted. Default is "All". /ENERGY refine the search to lines with upper level energy lower than ENERGY, expressed in Kelvins. /AIJ refine the search to lines with Einstein A coefficient greater than AMIN, expressed in s-1. /DELTA search for lines within DFREQ, expressed in MHz, from the cursor position. Default is 10 times the channel width. /FULL search for lines in the full frequency range covered by the current spectra. /IMAGE search for lines in the image sideband. Note that this is the default if the spectra lower axis unit is I (image). /LOOP by default, the cursor is invoked only once, but you can iterate indefinitely with the option /LOOP. Type 'E' to exit the loop. 1 LLIST [WEEDS\]LLIST List the lines from the line index. The line index is built with the LFIND command. 1 LPLOT [WEEDS\]LPLOT [NCHAN] Plot the line from the current line index (built from the last FINDLINE command). A vertical line is drawn at the rest frequency of the line. An optional NCHAN parameter may be given to define the frequency interval to be plotted around the line, expressed in number of channels (default 100) Arguments: NCHAN the frequency interval to be plotted, in channels (default 100) 1 MODSHOW [WEEDS\]MODSHOW Plot the results of MODSHOW over the current spectra. The command en- sures that the x-axis range and y-axis range are fixed so one can com- pare the predictions of the model with the observed spectra. 1 MODSOURCE [WEEDS\]MODSOURCE MODFILE ANTSIZE [/BACKGROUND TBG] [/OPACITY I] [/VERBOSE] Model the emission of a source at the local thermodynamic equilibrium (LTE). The model paramaters (column density, kinetic temperature, source size, line width and velocity offset for each species) are read from MODFILE. The modeled antenna temperature is stored in the TB_MODEL memo- ry. For convenience the current spectra is also stored in a memory, OBS, so one can easily overplot the result of the model on the observed spec- tra. Arguments: MODFILE the name of the file containing the parameters. The file must have one line per species with at least six columns containing respectively: 1) The species name 2) The column density for this species in cm-2 3) The exitation temperature in K 4) The source size in arcsecs 5) The offset velocity from the source VLSR, in km/s 6) The line FWHM in km/s One additional column may be used to select a different origin for each species: 7) The origin of this species (e.g. JPL or CDMS). If emp- ty, species with any origin are selected. The following options may be used at the end of the line: /ABSORPTION If this option is set, the component is as- sumed to be a foreground layer. See Belloche et al. A&A 559, A47 (2013) for details. /PARTFUNC Q Set the log10 of the partition function at the excitation temperature to Q. If not set, the partition function values (log-log interpolated/extrapolated at the excitation temperature) from the selected database are used. Lines that start with a "!" are treated as comments. ANTSIZE the antenna size in meters Options: /BACKGROUND set the background temperature to TBG, in K. Default is 2.73. /OPACITY I store the opacity of the Ith component in the TAU_MODEL memory. Components are numbered in the same order as in MODFILE, starting from 1. /VERBOSE prints partition function, lines frequencies, upper level energies and degeneracies, Einstein coefficients and opac- ity at the line center. 1 SCANFIND [WEEDS\]SCANFIND RESTFREQ This function loops over the scan index until it finds one that covers the given rest frequency. When the scan is found, it is loaded. Note that if several scans covers the same frequency, the command will find only the first one; other will be ignored. Arguments: RESTFREQ the rest frequency to search, in MHz. 1 ENDOFHELP