The Astrophysics Cross-Observatory Science Support (ACROSS) initiative aims to advance time-domain and multimessenger (TDAMM) science by facilitating the coordination of observational resources and scientific expertise. Its goal is to enable rapid, unified, and effective responses to astrophysical events — maximizing the scientific return of the astrophysics community.

ACROSS is a NASA-led effort, initially focused on supporting NASA's own fleet of space observatories, with the longer-term vision of potentially expanding to include observatories across the broader astrophysics community.

Advancing this field relies not only on technological innovation and scientific insight, but equally on the collaboration, communication, and infrastructure necessary to support multifaceted exploration of the universe.

The ACROSS system aggregates and normalizes supported mission schedule and observation data to provide a single queryable source for science situational awareness across NASA's ground and space observatories. By providing a unified interface to access and analyze this data, ACROSS empowers scientists to make informed decisions about observation planning, coordination, and execution.

ACROSS is committed to making astrophysics scheduling and observation data as openly accessible as possible. No account or login is required to read data from the ACROSS API. All GET endpoints are publicly accessible without authentication, allowing anyone to query schedules, observations, observatory configurations, and visibility information freely.

Authentication is only required for write operations — such as submitting or updating schedule data on behalf of an observatory. These actions require credentials issued to registered observatory partners.