A Comparative Study of Different Gaussian Process Methods in Exoplanet Atmospheric Transmission Spectroscopy Data Processing
The transit method is one of the important ways to study the atmosphere of exoplanets.Whe observing the atmosphere of exoplanets on the ground,the traditional transit method usually observes one or more comparison stars nearby the target star at the same time,and a series of differential spectra can be obtained.The system noise caused by the earth's atmosphere and instrument effect in the transit light curve will be modelled and removed using Gaussian process regression.Here we try a new method,that is,instead of using the differential spectroscopy,the light curves of the comparison stars are used as the relevant quantity of the Gaussian process to explore the system noise in the light curve,which allows for more flexible nonlinear mapping between the light curve of the target star and the simultaneously recorded time series,and thus can be used to explore the system noise existing in the transit signal in details.Furthermore,we also tested the case of no comparison stars.We applied the new method to one transit spectral data of the hot Jupiter WASP-69b.We find that for this WASP-69b transit data,the new method obtains better white-light transit depth accuracies than the traditional method when a reference star is used,the residuals of the spectroscopic light curves are generally smaller than those obtained by the traditional method,and acceptable results can still be obtained without a reference star and with a known transit center time.More tests on transiting data will further validate the advantages and applicability of the new method.
techniques:spectroscopicplanets and satellites:individual:WASP-69bmethods:data anal-ysismethods:statistical
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