Comprehensive magnetogram portal and archive service system (COMPASS): an IIIF-based portal for over 1.4 million historical magnetogram records

Historical magnetograms are fundamental records for space weather, space climate, and geomagnetism. However, they have rarely been published in searchable or viewable formats, posing a significant barrier to their use by the scientific community. To address this challenge, we developed the Comprehensive Magnetogram Portal and Archive Service System (COMPASS), an online platform for publishing and exploring historical magnetogram records. This paper presents two main contributions: the first public release of a historical magnetogram archive comprising over 1.4 million images, and a web portal that applies the International Image Interoperability Framework (IIIF) to make this dataset searchable and usable. Through its IIIF-compliant architecture, the portal enables researchers to interactively search, view, download, and compare these high-resolution images, which represent over 100 years of data from more than 100 observatories. The adoption of the IIIF standard transforms this large and diverse collection into an interoperable, analysis-ready resource for the research community. COMPASS is expected to accelerate cross-disciplinary collaborative studies of historical geomagnetic variability.