The Rubin Observatory Commissioning Camera (ComCam) is a scaled down (144 Megapixel) version of the 3.2 Gigapixel LSSTCam which will start the Legacy Survey of Space and Time (LSST), currently scheduled to start in 2024. The purpose of the ComCam is to verify the LSSTCam interfaces with the major subsystems of the observatory as well as evaluate the overall performance of the system prior to the start of the commissioning of the LSSTCam hardware on the telescope. With the delivery of all the telescope components to the summit site by 2020, the team has already started the high-level interface verification, exercising the system in a steady state model similar to that expected during the operations phase of the project. Notable activities include a simulated “slew and expose” sequence that includes moving the optical components, a settling time to account for the dynamical environment when on the telescope, and then taking an actual sequence of images with the ComCam. Another critical effort is to verify the performance of the camera refrigeration system, and testing the operational aspects of running such a system on a moving telescope in 2022. Here we present the status of the interface verification and the planned sequence of activities culminating with on-sky performance testing during the early-commissioning phase.
In the last couple of years, the Rubin telescope and site subsystem has made tremendous progress and overcome a few challenges. The insulated cladding on the dome is done and work is now focused on finishing the louvers, weatherproof cladding, interior work, light baffles, and the final fabrications. This has been done concurrently with the installation of the telescope mount, now mostly complete and approaching the beginning of functional testing in September-October, 2022. While work is being done on these two major subsystems, other major components and systems are being integrated and tested in a system spread configuration: M1M3 & M2 mirrors, the camera hexapod/rotator and the control software, including elements of the active optics control and the commissioning camera. Finally, the calibration system - an important contributor to achieving the exquisite photometry required by the Legacy Survey of Space and Time (LSST) - is being finalized.
The Vera C. Rubin Observatory is currently under construction on Cerro Pachón, in Chile. It was designed to conduct a 10-year multi-band survey of the southern sky with frequent re-visits (with both an intra- and extra-night cadence) to identify transient and moving objects. The mirror cell assembly was designed in Tucson, Arizona by the Rubin Observatory engineering department, and was tested twice in Tucson. The first testing campaign was performed at CAID industries, where the mirror cell was fabricated, using a steel mirror surrogate that has the same geometry and mass of the glass mirror2,4. The glass mirror is a single monolith that contains both the primary and tertiary mirrors on a single substrate. The testing results confirmed that the mirror support system was performing within the design specifications, and that it was safe to install the glass mirror on the cell. The second test campaign was performed at the Richard F. Caris Mirror Lab of the University of Arizona using the actual glass mirror16. This test campaign was performed under the test tower, which contains a vibration insensitive interferometer to measure mirror figure. This confirmed the mirror support system could achieve proper optical surface figure control for both primary and tertiary mirrors. After successful test campaigns at CAID, and the mirror Lab, the mirror cell assembly was disassembled, packed and shipped to the Rubin Observatory site at the Cerro Pachón summit in Chile. Upon arrival, the mirror cell has been integrated with the mirror surrogate once again to perform the third test campaign that confirmed the system has arrived safe and operational to the summit. This integrated system will be tested on the telescope mount assembly to verify that it still meets it requirements under the effects of variations in gravitational orientation, and dynamic (slewing) loads.
The Vera C. Rubin Observatory (Rubin Obs) (formerly Large Synoptic Survey Telescope - LSST) is an 8.4-m telescope, now under construction in Chile. In the last couple of years, the telescope has achieved tremendous progress, though like many other projects, progress has been curtailed for over six months due to the worldwide pandemic. This paper provides the high-level status of each of the telescope's subsystem. The summit facility (Cerro Pachon) and base facility (La Serena) have been substantially completed. The dome is expected to be finished by October of 2021, which will also allow the completion of integration and testing of the Telescope Mount Assembly (TMA). The integration and verification of the TMA is planned to be completed by the end of 2021. The two mirror systems, M1M3 and M2, have been fully tested under interferometers, showing they both satisfy their performance requirement, and both have been received at the summit facility. The M2 mirror has been successfully coated with protected aluminum, which is the first scientific coating produced by the new Rubin coating plant. The M1M3 mirror is planned to be coated with the same plant at the beginning of 2022. The auxiliary telescope and its principal spectrograph instrument, which will allow for real-time atmospheric characterization, has been commissioned. The Rubin environment awareness system (EAS), which includes the DIMM, weather station, all-sky camera, and facility environmental control, is operational. Significant progress has been made on the software for all of the above-mentioned subsystems, as well as the comprehensive telescope control system and the telescope operator interfaces.
The Vera C. Rubin Observatory is a joint NSF and DOE construction project with facilities distributed across multiple sites. These sites include the Summit Facility on Cerro Pachón, Chile; the Base Facility in La Serena, Chile; the Project and Operations Center in Tucson, AZ; the Camera integration and testing laboratories at SLAC National Accelerator Laboratory in Menlo Park, CA; and the data support center based at the National Center for SuperComputing Applications at Urbana-Champaign, IL. The Rubin Observatory construction Project has entered its system integration and testing phase where major subsystem components are coming together and being tested and verified at a system level for the first time. The system integration phase of the Project requires a closely coordinated and organized plan to merge, manage, and be able to adapt the complex set of subsystems and activities across the entire observatory as real effects are discovered. In this paper we present our strategy to successfully complete integration, test and commissioning of the systems making up the Rubin Observatory. We include discussion on (i) our strategy for integration activities and the verification of requirements (ii) a brief summary of construction status at the time of this paper, (iii) early integration activities that are used to mitigate risks including the use of the Rubin Observatory's commissioning camera (ComCam), planning for the integration, testing and verification of the primary science instrument - LSSTCam, and lastly, (v) Science Verification through short concentrated survey-like campaigns. Throughout this paper we identify where key performance metrics are addressed that directly impact the Rubin Observatory's 10{year Legacy Survey of Space and Time (LSST) science capabilities - e.g. image quality, telescope dynamics, alert latency, etc...
The optical axis of a Nasmyth telescope should be perpendicular to the Elevation axis and pass through the rotational center of the Tertiary mirror turret rotator. Realized by aligning a laser beam to the rotational center of the two field derotators. A high precision Pentaprism mounted on the Tertiary mirror rotator deviates the laser beam by 90° defining the optical axis onto which the Primary and Secondary mirrors are mounted and aligned. We present method, procedure, tools and results for two examples of Nasmyth Telescopes; the 4.1m SOAR and the LSST's 1.2m Auxiliary Telescope.
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