2025ApJ...992...23T

While plane-of-sky magnetic field observations in molecular clouds are now common, observations of their line-of-sight magnetic field remain limited. To address this issue, M. Tahani et al. developed a technique based on Faraday rotation. The technique incorporates an ON-OFF approach to identify the rotation measure induced by the magnetic fields associated with the cloud. The upcoming abundance of observations of Faraday rotation from the Square Kilometre Array and its pathfinders necessitates robustly tested software to automatically obtain line-of-sight magnetic fields of molecular clouds. We developed software, called MC-BLOS (for molecular cloud line-of-sight magnetic field; DOI:10.5281/zenodo.15338512), to carry out the technique in an automated manner. The software's inputs are Faraday rotation of point sources, maps of extinction or column density, results from chemical evolution code, and a parameter file that allows the user to specify the cloud name or other parameters pertaining to the technique. For each cloud, the software invokes a set of predefined initial parameters such as density, temperature, and surrounding boundary, which the user can modify. The software then runs the technique automatically, outputting line-of-sight magnetic field maps and tables (including uncertainties) at the end of the process. MC-BLOS generates diagnostic files for result evaluation and input parameter refinement, allowing for expert judgment in parameter selection. We have tested the software on previously published clouds, and the results are consistent within the reported uncertainty range. This software will facilitate the analysis of forthcoming observations of Faraday rotation, enabling a better understanding of the role of magnetic fields in molecular cloud dynamics and star formation.