The Per-Source Observation (PSO) approach for monitoring amplitude calibrators

The Per-Source Observation (PSO) approach for monitoring the secondary amplitude calibrators (quasars) on a per-source basis is a scheduling advancement over the previous per-group observing before Cycle 9. In this poster, we will present the motivation, requirements, and current implementation of this new observing approach. This includes changes in the cadence for the monitoring in Band 3, an increase in the number of bands regularly monitored, including Band 9 to support high-frequency observing, and the newly available ALMA Band 1. The observing strategy optimizes the number of sources observed depending on their need for flux density updates. It also considers the available weather conditions and optimizes for high elevation. Further, the availability of solar system objects as primary flux density calibrators is considered, and additional quasars are assigned as flux density transfer sources, while minimizing the time between comparison observations. This poster provides additional details specifically on the PSO implementation and evaluation of its global impact on the amplitude calibrator monitoring in science operations, complementing the poster presentation on "Operational Aspects of ALMA Flux Density Calibration".