Celestial Standards
Meridian: A shared reference that can be examined.
Meridian brings observatories together to compare measurements, maintain common references and document the revisions that make a sky record usable.
Historical sky imagery · NASA/JPL, Spitzer Helix nebula, 2007; not a post-Break reference catalogue · Image credits
Scientific purpose
The program supports cross-observatory calibration and reference comparison. It preserves source observations, instrument checks and the reduction choices behind a reference product. Previous versions remain available as part of the scientific record.
Observing approach
Teams compare independent observations rather than relying on a single instrument. When a reference changes, the record identifies the change and the limits of transforming earlier measurements.
Interpretation and limits
A reference is a documented comparison system, not an explanation of every discrepancy. Meridian separates measurements from hypotheses about their cause and keeps uncertainty attached to each revision.
Program record
Published methods and records use the Foundation’s common provenance and correction requirements. The responsible office coordinates scientific questions with the relevant research team.