The Application of Astrophysics Spectral Databases for SubLIME Data Automation

The SubLIME Lab (Sublimation Laboratory Ice Millimeter/submillimeter Experiment) located at NASA Goddard Space Flight Center studies the connection between ice and gas chemistry of astrophysical and planetary environments by using IR spectroscopy to study ice-phase chemistry and submillimeter spectroscopy to study sublimated products. SubLIME creates a myriad of complex spectra containing hundreds of pure rotational transitions and relies on accurate spectral catalog databases (e.g., JPL and CDMS) to identify the sublimated molecular composition. To alleviate the tedious and time-consuming challenges of spectral assignment, we have automated this process with a Python-based program capable of analyzing these complicated laboratory spectra to find peaks and assign them to molecular catalogs based on user-defined parameters (atomic composition, frequency offset, and intensity cutoff, etc.). Using this program, we analyzed a spectral data set of a methanol (CH₃OH) ice photolysis experiment. Within a 6 GHz spectrum, we were able to identify 177 peaks, assign them to their molecular catalogs, and identify 22 molecules within 45 seconds. Furthermore, the chemical abundance ratios of the assigned products can then be quantified using a rotation diagram analysis. The program creates interactive plots to visualize the identified peaks and LaTeX tables of the spectral assignment for faster data analysis and publication turnover. The results can then be compared to astronomical observations to provide insight on how chemical composition may change due to sublimation. This presentation will describe the automated data analysis procedure and some challenges encountered when using astrophysics spectral databases.