The Calar Alto Schmidt-Lemaitre Explorer (CASTLE) is an innovative 35 cm robotic telescope aimed at demonstrating the impact and performance of curved detectors for astronomical observations. This telescope will use a spherically curved science-grade sensor matching its curved focal surface and it will be installed at the Calar Alto Observatory in Spain. In this paper we will show the design and we will present the status of the opto-mechanical design and construction. We will also show the preliminary results of the straylight analysis and the general plan towards commissioning and first light in 2021/2022. © 2020 SPIE.

The authors acknowledge the support of the European Research council through the H2020 - ERC-STG-2015 – 678777 ICARUS program, the H2020-ERC-PoC-2018 - CURVE-X - 839271, the MERAC foundation and the European Astronomical Society who are funding the project. This activity was partially funded by the French Research Agency (ANR) through the LabEx FOCUS ANR-11-LABX-0013.

Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation IV 2020; Virtual, Online; United States; 14 December 2020 through 22 December 2020; Code 166575.--Proceedings of SPIE - The International Society for Optical Engineering Volume 11451, 2020, Article number 114510A