Data formatΒΆ

The data file you will need to feed to the fitter should contain one source per line. Each line should contain 3*(n+1) columns, where n is the number of wavelengths/filters for which fluxes are given:

  • Column 1 should contain the source name, with no spaces

  • Columns 2 and 3 should contain the source coordinates

  • Columns 4 to 3+n should contain a flag for each flux, where the flag can take the following values:

    • 0 for data points which are not valid or used

    • 1 for valid data points

    • 2 for lower limits

    • 3 for upper limits

    • 4 for valid data points (as for 1) but where the fluxes and errors are expressed as \(\log_{10}{\rm [flux]}\) and \(\log_{10}{\rm [error]}\). This is useful for sources which have a magnitude with a large error, which can then be converted to \(\log_{10}{\rm [flux]}\) and \(\log_{10}{\rm [error]}\) without worrying about the conversion from magnitude and magnitude error to linear fluxes and errors.

  • Columns 4+n to 3*(n+1) should contain the fluxes and flux uncertainties, alternated, in mJy. For lower and upper limits, the error should be set to the confidence placed on the limit, with 0 corresponding to 0% and 1 corresponding to 100%. For example, in the case of an upper limit, setting the confidence to 1 effectively forbids any models to be larger than the upper limit, while setting the confidence between 0 and 1 allows such models, but introduces a \(\chi^2\) penalty dependent on the confidence. Setting the confidence to 0 effectively disables the upper limit.

We refer to this format as the fitter data format. Note that in a single data file, all lines should have the same number of columns. If one or more fluxes are not available for a specific source, the flag for these fluxes can be set to 0.

An example data file with four fluxes per source is shown here:

SSTGLMC_G009.8925-00.3420 9.89250 -0.34200 1 1 1 1   6.869e+01   6.869e+00   1.512e+02   1.512e+01   1.626e+02   1.626e+01   9.015e+01   9.015e+00
SSTGLMC_G009.8940-00.3367 9.89408 -0.33675 0 0 1 1  -9.999e+02  -9.999e+02  -9.999e+02  -9.999e+02   7.412e+00   7.412e-01   1.199e+01   1.199e+00
SSTGLMC_G009.8943-00.3378 9.89430 -0.33783 0 0 1 1  -9.999e+02  -9.999e+02  -9.999e+02  -9.999e+02   4.462e+00   4.462e-01   6.927e+00   6.927e-01