This documentation manual covers the basic usage of the Weeds extension. More detailed information on each command is available using the Gildas online help, e.g.:
[fontsize=\scriptsize]
LAS90> help modsource
WEEDS\MODSOURCE = "python weeds/modsource.py"
[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
database for each species:
7) The name of the database to use for this species. If
empty, the default database (selected with USE IN) is
used.
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.
For a more detailed description of the Weeds extension, we refer the interested reader to Maret, Hily-Blant, Pety et al., Astronomy & Astrophysics 526, A47 (2011). This paper describes the implementation of the extension, and gives more details about the spectroscopic databases that it uses, and explains how spectra are modeled7,
Weeds developers can be contacted by email at gildas@iram.fr. Bug reports should also be sent to this address.