Type: Talk
Session: Tools for Image Cutouts and Reprocessing
Authors: Shenming Fu

Abstract: We will mainly talk about a pipeline that performs rapid image subtraction and source selection to detect transients, with a focus on identifying gravitational wave optical counterparts using the Dark Energy Camera (DECam). This pipeline serves as a broad community effort from NOIRLab. We process DECam data and build difference images using the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST) Science Pipelines software, and we use flags and principal component analysis to select transient candidates from the catalog per exposure, without associating the results from different exposures. Those candidates will be sent to brokers for further classification and alert distribution. We validate our pipeline using archival data that span various types of objects, including variable stars (in a diffuse galaxy or the Milky Way bulge), supernovae, a kilonova (GW170817), stellar flares, and serendipitous sources. Overall, the data processing produces clean light curves that are comparable with published results, which proves the photometric quality of the pipeline. Real transients can be well selected by the pipeline when sufficiently bright (S/N ≳ 15). Although this pipeline is designed for DECam, our method can be easily applied to other instruments and future LSST observations.