At the end of October 2018 the SKA SDP Consortium submitted its Critical Design Review (CDR) documentation pack. Contained in this were the formal deliverables of the design consortium covering all aspects of the SDP architecture, system engineering and programmatics (the documents are available here).  The documents were received by the CDR reviewers (consisting of 3 external members and 15 internal to SKAO) who proceeded to generate clarification questions, requests and notes in the form of observations (called OARs after the Observation Action Register approach commonly used for them). Where possible these were addressed via communication exchanges in JIRA OAR tickets.

From 15th to 19th January 2019 members of the SDP Consortium then visited the SKAO HQ at Jodrell Bank (see figure 1), where direct discussions took place in the new SKAO Council Chamber (see figure 2), to further explore the architecture and identify risks as part of an SEI Architecture Tradeoff Analysis Method (ATAM).