After 10 years of construction, NSF–DOE Vera C. Rubin Observatory is less than one year away from the start of its transformational movie of our changing night sky. In preparation for this monumental production, the observatory has just successfully completed a series of full-system tests using an engineering test camera. This accomplishment sets the stage for the last step of Rubin construction: installation of the 3,200-megapixel LSST Camera (LSSTCam)—the largest digital camera in the world.
Rubin Observatory is jointly funded by the US National Science Foundation and the US Department of Energy’s Office of Science. Rubin is a joint Program of NSF NOIRLab and DOE’s SLAC National Accelerator Laboratory, who will cooperatively operate Rubin.
The engineering test camera, or commissioning camera (ComCam), has a mosaic of nine CCD sensors with a total of 144 megapixels. It covers an area about twice that of a full Moon. Over the seven-week ComCam engineering test campaign, from 24 October to 11 December 2024, approximately 16,000 exposures were acquired to test Rubin Observatory’s hardware and software systems and data pipeline.
ComCam is a much smaller version of the huge LSSTCam. The LSSTCam will next be installed on the telescope in place of ComCam, where it will help carry out Rubin’s 10-year Legacy Survey of Space and Time. With 189 CCD sensors, LSSTCam’s field of view will be 21 times that of ComCam, with each single image capturing an area on the sky about 45 times the size of the full Moon. Coupled with Rubin’s fast-moving, 8.4-meter telescope, the LSSTCam will capture very faint objects and objects that change in position or brightness at a rate the science community has never seen before.
The tests conducted by Rubin’s international commissioning team, which is composed of hundreds of engineers, scientists, and observing specialists, included:
- Verifying the Active Optics System that maintains the precise positions and shapes of the telescope’s three large mirrors as the telescope points in different directions
- Checking that the telescope’s complex systems were all working together
- Demonstrating the early image quality capabilities of the system in all six filters
- Shipping the large amount of data quickly from Chile to the Rubin Data Facility at the Department of Energy’s SLAC National Accelerator Laboratory
- Running the complex data processing pipelines
Rubin Observatory (encompassing the Simonyi Survey Telescope, the camera, data systems, networks, and people) performed exceptionally well during the engineering test phase. It delivered high-quality images within the first hours, even with most of the detailed optical adjustments and environmental controls not yet fully activated. Thanks to the dedicated efforts and talents of thousands of people over many years, the telescope had been assembled with all its complex parts positioned correctly to better than about one millimeter. Equally satisfyingly, the high speed network connecting Chile and the data center at SLAC, the data systems, and algorithms for analyzing the data worked well too.
“The success of the engineering test phase has given a surge of excitement and anticipation to the team,” says Sandrine Thomas, Deputy Director for Rubin Construction. “Reaching this milestone has offered a small taste of what is to come once Rubin Observatory begins its 10-year survey.”
The next few months will focus on installing the LSSTCam—one of the last major steps in the journey toward ‘First Look’ when images from the complete Rubin Observatory will be shared with the world for the first time. Then, after the final phase of full system testing and verification, Rubin Observatory will begin the most comprehensive data-gathering mission in the history of astrophysics.
By repeatedly scanning the entire southern night sky for a whole decade, Rubin will create an ultra-wide, ultra-high-definition time-lapse record of our changing cosmos. This will be the greatest movie of the Universe ever created, bringing the night sky to life and yielding a treasure trove of discoveries: asteroids and comets, pulsating stars, supernova explosions, and so much more. With Rubin data, we will understand our universe better, chronicle its evolution in unprecedented detail, delve into the mysteries of dark energy and dark matter, and reveal answers to questions we have yet to imagine.
Editor's note: A version of this article was originally published as a press release by Rubin Observatory.
