SCORPIO: Opto-Mechanical-Thermal (OMT) Integration to Commence in Spain FY25Q3

In January a long-awaited milestone for SCORPIO, the Spectrograph and Camera for Observations of Rapid Phenomena in the Infrared and Optical, was realized: the cryostat and electronics were shipped from the prime contractor, Southwest Research Institute (SwRI) in San Antonio, TX, to their Opto-Mechanical-Thermal (OMT) integration subcontractor, Fractal, in Spain. Survival testing is underway, with the leak check completed and the first thermal cycle planned for the end of April. Over the next 12 months, the near-infrared and visual subsystems will undergo integration, alignment, and testing. Several months of functional and pre-acceptance system testing will follow, concluding the Build Phase. The next phase, Telescope Integration and Commissioning, is expected to kick off in Spring 2026 with the delivery of SCORPIO to Gemini South.

SwRI’s delivery of the near-infrared detectors and the associated cryo-cables will require careful attention. The design progress has been delayed by persistent stray light in the test chamber and a major relocation/rebuild of the test lab at SwRI headquarters. The next test cycle is planned for the end of the month. Without further performance issues, the design will be finalized, cables will be fabricated, and detector calibration will resume.

Gemini, SwRI, and Fractal are collaboratively adapting to meet these challenges and drive the project forward. Gemini Engineering continues to support the design centers in resolving issues and is taking on a more active role traditionally held by the prime contractor.

• Gemini Engineering led the redesign of the atmospheric dispersion corrector (ADC) assembly. The original components are being shipped to Chile for further evaluation and reuse potential.
• Gemini Engineering has accepted responsibility for completing the Instrument Software and Data Reduction Pipeline. Although detailed handover plans are still being finalized, Gemini teams are already making considerable progress.
• Gemini Engineering staff traveled from Chile to Spain to assemble the helium cooling system, enabling instrument operation and testing using a configuration that more closely matches that of Gemini South.

Additional initiatives undertaken by Gemini to enhance collaboration and planning include:

• Development of an integrated master schedule that consolidates the work packages of all three organizations into a unified timeline to enhance project visibility, monitor progress, and support more informed decision-making.
• Resuming monthly meetings of the Acceptance & Commissioning Working Group to develop the comprehensive plans and procedural framework necessary for the formal acceptance of SCORPIO. This effort includes the systematic characterization of instrument performance across all observing modes and the verification and closure of any outstanding Concept of Operations and Science Requirements.
• Restructuring the Pre-Integration Review to prioritize critical deliverables, save time, and alleviate pressure on SwRI’s overextended personnel and budget resources.

SCORPIO is an eight-channel imager and spectrograph covering 0.37–2.35 microns across a 3 x 3 arcminute field. It provides R∼4000 spectroscopy and simultaneous imaging in g, r, i, z, Y, J, H, and KS bands. With negligible readout time, it enables high-time-resolution observations. SCORPIO is optimized for transient characterization and rapid follow-up, supporting diverse science from Solar System bodies to exoplanets, compact objects, active galactic nuclei, and explosive events. With SCORPIO, Gemini South will play a significant role in the era of NSF–DOE Vera C. Rubin Observatory by enabling rapid-response follow-up observations.