Tuning the Legacy Survey of Space and Time (LSST) Observing Strategy for Solar System Science: Incremental Templates in Year 1

The Vera C. Rubin Observatory is due to commence the 10-year \gls*{lsst} at the end of 2025. To detect transient/variable sources and identify \glspl*{sso}, the processing pipelines require templates of the static sky to perform difference imaging. During the first year of the LSST, templates must be generated as the survey progresses, otherwise \glspl*{sso} cannot be discovered nightly. The incremental template generation strategy has not been finalized; therefore, we use the \gls*{maf} and a simulation of the survey cadence (\baselinefull) to explore template generation in Year 1. We have assessed the effects of generating templates over timescales of days-weeks, when at least four images of sufficient quality are available for $\geq90\%$ of the visit. We predict that \gls*{sso} discoveries will begin $\sim$2-3 months after the start of the survey. We find that the ability of the LSST to discover \gls*{sso}s in real-time is reduced in Year 1. This is especially true for detections in areas of the sky that receive fewer visits, such as the \gls*{nes}, and in less commonly used filters, such as the $u$ and $g$-bands. The lack of templates in the \gls*{nes} dominates the loss of real-time \gls*{sso} discoveries; across the whole sky the \gls*{maf} \gls*{mba} discovery metric decreases by up to 63\% compared to the baseline observing strategy, whereas the metric decreases by up to 79\% for \glspl*{mba} in the \gls*{nes} alone.