The 35th annual conference on Astronomical Data Analysis Software & Systems 2025 in Görlitz, Germany

In an era of increasingly complex and numerous astronomical instruments, a standardized description of observation targets becomes more and more crucial for efficient planning and archiving of astronomical observations.

To ensure seamless out-of-the-box interoperability between different systems and instruments, ESO has internally proposed a new unified standard (ESO-371803, “Astronomical Targets at LPO”) to describe astronomical target objects and scenes. The scope of this standard includes Data Flow System (DFS) tools such as the Phase 1 & 2 preparation systems, Exposure Time Calculator (ETC), Observation Preparation Tool, as well as back-end applications such as Pipelines, Quality Control and Science Archives.

The ScopeSim general purpose astronomical observations simulator (Leschinski et al. 2020) aims to become an integral part of the Phase 2 preparation system in the form of an “Exposure Time Simulator” (ETS) front-end, specifically for instruments on ESO’s under-construction “Extremely Large Telescope” (ELT). To support this, we are developing a new simplified target description package ScopeSim-Targets to become part of the overall ScopeSim ecosystem (Haberhauer et al. 2024). ScopeSim-Targets is designed to bridge the gap between ScopeSim and ESO’s DFS infrastructure.

The new package enables users to take full advantage of the enhanced whole-scene simulation capabilities provided by ScopeSim and subsequently directly re-use their target descriptions in ESO’s proposal tools, creating a streamlined end-to-end workflow user experience. This also introduces an essential ability for both science users and operators to efficiently communicate and plan observations at such a complex machine as the ELT and its instruments.

Additionally, the new syntax is designed to be considerably more self-consistent and straightforward from the user’s perspective compared to the previously used ScopeSim_Templates package. On the implementation side, the new package will heavily utilize the extensive and well-tested framework provided by the astropy.modeling sub-package wherever applicable.