The Telluric Corrected IAG Solar Flux Atlas

The telluric-corrected IAG solar flux atlas was derived from ~100 spectra taken on the Vacuum Vertical Telescope (VVT) at the Institut für Astrophysik in Göttingen, Germany. The resolution of the data is R~10⁶ . The spectra are iodine calibrated and span from 9020-19990cm^-1 (500-1100nm).

The data are presented in fits tables. The IAG telluric corrected solar atlas is "iag_telfree.fits" with column names 'v', 's', 'err', 'flags' for the wavenumber array, solar spectrum, error, and flag array. Please refer to 'open_data.py' for details on the telluric spectra column names - this script will open the solar atlas and telluric spectra and plot each (check that the filenames and data path are correct before running).

Things to watch out for:

1. There are a few places where the continuum correction did not work well. Continuum stitching occurs at every multiple of 10cm-1. If you see a weird feature at one of these points, it could be due to mismatched continua on either end. Also around the laser line at 633nm the continuum offsets between spectra are not corrected well. This is due due to limitations in how offsets are corrected for in the fits, but this can be corrected for by performing your own continuum normalization to the spectra in this region.
2. Sometimes the spline model would try to fill in the core of a telluric line. These usually are identifiable using the flag array if you are using the solar model, but may affect telluric analysis since a slight over subtraction occurred in these lines. This effect is worse when the continuum is low (notably around 9200cm-1, 15233cm-1, and 16955cm-1). One could excise these points using the flag array to identify them and then interpolate over these regions if desired.
3. The iodine lines cause small, sharp residuals in the blue end of the spectra due to changes in the cell’s spectrum w.r.t. the template over time. The solar spectrum uncertainties capture these well, but note that these residuals will be worse in the telluric spectra.
4. All spectra were shifted to match the wavelength solution of the Salami & Ross 2005 iodine template

For more details, please refer to the paper, Baker et al 2020, The IAG Solar Flux Atlas: Telluric Correction with a Semi-Empirical Model. Questions are welcome; feel free to direct them to the corresponding author.