LOFAR is preparing the upgrade to the LOFAR2.0 system, which will offer simultaneous low- and high-band observing, increased field-of-view, and various other improvements to the sensitivity and operation of the telescope. The new system will generate considerably more data than the current one. The need for processing and storage of this data represents a significant challenge, as it outstrips current affordable solutions. To realize the goals of the new Observatory, the ILT board has approved a data life cycle that optimises science data processing capacity and efficiency with respect to affordable data storage. This includes data retirement. The ILT anticipates that (final) science data products, generated through standard pipelines (such as image cubes) can be kept available indefinitely (under open access policies), but that raw/intermediate products may only be retained for further processing within a restricted dwell time.

To prepare the ILT infrastructure for the LOFAR2.0 data challenges, a first step needs to be taken now that involves the retirement of early Cycle data from the LOFAR Long-Term Archive (LTA). After careful analysis, it has been concluded that data from Cycle 0 up to and including Cycle 6 is either low in metadata quality or already valorized and published (https://science.astron.nl/telescopes/lofar/science-with-lofar/lofar-papers/) or, based on the download statistics, of little demonstrable interest to the current community. The ILT has therefore approved that mid-2024 this data will be deleted from all LTA sites.

Through this notification, we give the opportunity to any users (i.e. not only the projects’ PI’s) who may need to retrieve data from these early LOFAR Cycles, to signal this to the Observatory to coordinate the data download. The requests will be evaluated by the Observatory for technical feasibility and reviewed by the ILT-board for approval. We emphasize that all data concerned is public data.