Input files

Input rules to MyGIsFOS provide all the needed calculation parameters, the list of stars to be processed, the list of regions to be used, and the synthetic spectra grid. They must be called after the fortran unit used to read them (see below), otherwise the code will not recognize them. However, such names might just be symbolic links to a file of whatever name. For instance, the list of stars to be processed is to be provided as fort.14, but you can always

ln -s my_star_list_file.txt fort.14

And it will work just fine. MyGIsFOS uses a fewother fortran units for input-output, so it is recommended not to have any file called fort.* but the ones here described in the directory where the code is running, to avoid them to interfere with the code or be overwritten.

fort.10: list of files containing the spectral regions used by MyGIsFOS

Measurement and continuum regions are provided in one or more files whose names are entered, one per line, in fort.10. This is done to allow the user to choose how to organize his region lists, so that e.g. one can place regions for each ion into separate files, or, on the other extreme, everything can be placed in a single file. fort.10 format is a simple list of file names, one per line. Any line beginning with a hash (#) is skipped as comment. As an example, fort.10 might look like this:

#this is a comment line

#another comment line

There is no need for the region lists to be given in any order, all the files are read, the regions from each lumped in a single list, oredered for increasing wavelength, into MyGIsFOS.

Region files The files describing the regions whose names are listed in fort.10 have the following format:

#595.643 595.703 2 26 00 1 1 1 0.859 #595.669 Y/Y see next
595.694 595.703 2 26 00 1 1 1 0.859 #595.669 Y/Y
596.104 596.167 2 -1 00 1 1 1 0.0000 #
596.352 596.429 2 -1 00 1 1 1 0.0000 #
596.975 597.041 2 -1 00 1 1 1 0.0000 #
597.825 597.871 2 22 00 1 1 1 0.0000 #

Where the columns are: starting wavelength (nm) ending wavelength (nm), frame number in the synthetic grid, element/ion code, flag for general use, flag for use in Vturb iteration, flag for use in Teff iteration, lower energy (eV), and comment.

fort.11: parameters file

This file contains parameters affecting the general behavior of the code, such as threshold for line rejections or the level of precision to which to stop parameter iteration. It is particular because its format is constrained, i.e. the order of the parameters cannot be changed. A typical example is:

1e-16 #probmin: minimum accepted probability for a line
0.1 #slopemin: minimum accepted slope to trigger Vturb iteration
0.05 #fe2min: minimum FeI/FeII difference to trigger gravity iteration
0.01 #maxexctslope: maximum slope acceptable of the exct. pot. vs. abundance relation
50 #maxtdiff, maximum temperature difference.
0.0005 #ewmin: minimum accepted line EW
0.012 #ewmax: maximum accepted line EW
0.8 #ewdrj: the line is rejected if ABS(EW-OEW).gt.ewdrj*min(EW,OEW)
3. #ew_noise: the line is rejected if EW is smaller than this factor times the noise dominated EW
2. #nclip: number of sigmas for average abundance clipping
0.25 #freecont: maximum admitted continuum variation in MINUIT. -1 locks the continuum.
1000 #nloopmax: maximum number of iterations
0. #fwhm_override: if not 0, assumed line fwhm. If 0, grid broadening is used instead.
2 #nalp2: number of alpha elements to be used in alpha enhancement determination
14 00
20 00 #these are the ions used in alpha enhancement estimation...
0.1 #alphamin: minimum alpha enhancement difference to trigger iteration
0.6 #pnfc: pseudomedian factor in continuum normalization.
6 #policy: parameter damping policy
0 #norenorm: disables pseudonormalization if =1
100 #sncap: artificially caps S/N to this value if not 0

A single value is read from each line, so that everything after the space is ignored. The comments included are just for user’s convenience and can be changed at user’s will. A few notes:

fort.12: the binary synthetic spectra grid

The synthetic grid is contained in a specially formatted binary and linked (or renamed) to fort.12. This is done to reduce its size (even like this, the grid is easily the largest input file of MyGIsFOS, easily passing 1Gb), speed up read-in, and reduce the likelihood of errors. The grid file contains, apart from the actual synthetic spectra, descriptors for the parameter space covered (values in Teff, log g, metallicity etc.) the assumed solar abundances used in the calculation, and the instrumental broadening applied to it. The grid is currently converted to binary by the companion program makegrid, and it's instrumental broadening allied by broadgrid: the grid must be passed to MyGIsFOS already broadened. See the dedicated section for more information.

fort.14: the input star list

This file contains the list of stars to be analyzed by MyGIsFOS. The record for a star looks like the following example

#This is a comment line STAR 17482159 4936 2 0.0 1.5 1 2.5 1 0.0 1 1 FRAME 1 ASCIN 17482159-3706199_final_l.dat FRAME 2 ASCIN 17482159-3706199_final_u.dat