Searches After Gravitational-waves Using ARizona Observatories (SAGUARO): Updating Optical Counterpart Search Methods

The Searches After Gravitational-waves Using ARizona Observatories (SAGUARO) program has been working to identify optical counterparts to gravitational wave (GW) events since 2019. During the third LIGO-Virgo observing run (O3), we utilized the 1.5m Mt. Lemmon telescope located near Tucson, Arizona as our discovery engine. Using this telescope, we were able to tile portions of GW event localizations in an effort to identify optical counterpart candidates through image subtraction. The 2.3m Bok telescope located on Kitt Peak is currently undergoing updates, and will soon be added to SAGUARO’s telescope network. It has the potential to improve our search methods by acting as a second discovery engine alongside the Mt. Lemmon telescope, giving us deeper images and more options for a tiling strategy. In preparation for this telescope integration and the upcoming LIGO-Virgo observing run (O4), we have started making updates to our pipeline to ensure that data from the Bok telescope can be run through our real-time data reduction and image subtraction software. We present the first results of the integration of the Bok data into the SAGUARO pipeline, as well as recommendations for additional updates needed for O4.