From spectra with AuxTel to cosmology with LSST
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Cosmology has experienced a great development during the last decades, being today a precision science with the arrival of large cosmological surveys, such as DES, DESI and Euclid. In the coming years, the Large Survey of Space and Time (LSST) will start to carry out a massive survey which will provide data with statistical errors below the systematic uncertainty due to photometric calibration. Given this increase of statistical precision, systematic effects are becoming the main source of uncertainty. In this regard, measuring colours and calibrating them is a crucial task for current and future photometric cosmological surveys in their way to obtain reliable cosmological measurements. This is particularly important for obtaining cosmological information from supernovae and to compute photometric redshifts. One of the main sources of photometric uncertainty is associated with atmospheric transmission. To deal with atmospheric effects, LSST counts with a companion telescope, the Auxiliary Telescope (AuxTel), whose purpose is to measure the atmospheric transparency and to derive colour corrections based on spectroscopic observations. In this presentation we will go through the latest improvements carried out on AuxTel, the methodologies that we are developing to properly extract the spectra and the method that we are proposing to derive colour compensations based on spectroscopic observations with AuxTel to be applied to LSST’s photometry.
