Small-Sized Telescope Harmonization Process and Status

By: Wolfgang Wild, CTAO Project Manager

CTA is a large science infrastructure with many individual units and a high degree of complexity. There are many good reasons to design and implement the simplest and most harmonized system possible. In fact, a high degree of simplification will be a crucial success factor both during construction and operation. This need for harmonization applies to many subsystems and components of the array. One prominent area concerns the Small-Sized Telescope (SST) where harmonization is of very high importance due to the large number of units to be built, operated and maintained.

Recognizing this, the CTA Observatory (CTAO) Project Office initiated discussions among the SST technical teams and shareholders in February 2018. As a result, the shareholders and those observers interested in providing SSTs as an in-kind contribution unanimously agreed on 9 May 2018 to implement only one SST design at the observatory.

Concerning the process to arrive at a single SST design from three proposed designs, the CTAO Council mandated the CTA Project Manager to carry out an SST harmonization review involving external experts. Following this mandate, a Request for Information was issued on 1 August 2018, resulting in three submissions by the deadline of 31 October 2018.

In November 2018, the Council unanimously approved the appointment of the members and charges of the external SST Harmonization Review Panel. The panel formed and conducted four remote conferences between 7 January and 4 March 2019 and held a final in-person meeting with the three SST teams on 27-29 March 2019. The report of the panel was delivered on 3 April 2019 and was immediately made available to the Council and the submitting teams.

Based on the review findings and recommendations, and taking into account funding considerations, the CTAO Management formulated its proposal for a unified SST design (the “CTA-SST”). In its June 2019 meeting and following the CTAO Management proposal, the Council decided that “the CTA-SST design should be based on the ASTRI/CHEC design (pictured above), taking into account the experience gained from all designs.” Since June 2019, various discussions have taken place among the teams and shareholders interested in joining the common SST effort. It is expected that a CTA-SST Consortium will form by the Council meeting this November. The teams that have decided not to join the CTA-SST Consortium are looking into other areas of contribution to CTA.

As expected, reaching this point has not been an easy process. We recognize the years of dedication and hard work that have been invested into each of the proposed designs. I would like to thank the SST teams and the panel of reviewers for their participation and diligence as we continue our pursuit to build the best instrument possible for our collective goals.