Weeks 14-15 of the on-sky commissioning campaign with LSSTCam included continuation of the SV surveys and other targeted observations, ongoing on-sky engineering with an emphasis on characterizing and enhancing the delivered image quality, as well as in-dome calibration systems commissioning. The nights of 24-31 July were all dedicated to closed-dome activities due to winter weather conditions, with the exception of on-sky engineering on 28 July.
Activities during the past two weeks:
- During nights with planned SV survey operations driven by the Feature Based Scheduler (FBS), the rate of acquired visits matched expectations from the survey simulations. As noted previously, while the system has demonstrated capability to meet the LSST design specifications for delivered image quality, the distribution of delivered image quality during the SV surveys is not yet consistently meeting the design specifications for the LSST 10-year survey. Currently, the leading causes of image degradation are understood to be related to dome seeing, mirror seeing, and the static optics alignment during individual visits. The consistency of the delivered image quality is expected to improve with ongoing work on the dome ventilation and Environment Awareness System (EAS), primary-tertiary mirror (M1M3) thermal control, and optimization of the Active Optics System (AOS) control loops.
- Testing to validate the AOS open loop look-up tables (LUTs) for elevation and physical rotator angle over an extended operational range.
- Target-of-opportunity observations for the gravitational wave event LIGO/Virgo/KAGRA S250725j were acquired on 28 July 2025.
- Multiband observations of the LSST Deep Drilling Field (DDF) ELAIS-S1 with a larger dither pattern than the standard LSST DDF observation strategy were taken to evaluate the impacts of reflected, stray, and scattered light, as well as internal calibration. These observations will be used as input to optimizing the dither strategy for the LSST DDFs.
- Multiband observations of the New Horizons field to evaluate difference imaging performance in dense stellar fields.
- Continued observations of a moderately dense stellar field to complete a full set of ugrizy measurements after the sequencer update for LSSTCam. These observations are used to refine the astrometric camera distortion model and photometric illumination correction, and to evaluate the internal astrometric and photometric calibration performance.
- Measurements to produce monochromatic flats for the griz bands to characterize the chromatic response of the system.
- Continued work on the M1M3 thermal control system.
- The LSSTCam Filter Exchange System (FES) experienced a fault on 24 July 2025 that impacted one of the filter sockets. The g band filter was successfully removed from the socket and inspected, and the engineering pinhole filter was installed in its place. The currently loaded filter set is uriz + pinhole. Currently, four of the five LSSTCam filter sockets are available for use. Rubin Observatory is developing plans for a schedule of filter swaps and corresponding strategy for the remaining SV survey operations considering availability of four filter sockets.
Several reports and analyses from the on-sky commissioning campaigns were presented at the Rubin Community Workshop in multiple plenary and breakout sessions.
The Rubin Observatory Survey Strategy Team is developing and deploying tools to provide quantitative details and visualizations of the progress of on-sky observing campaigns, including the SV surveys. These resources include roughly weekly summaries of the SV survey progress (with completed visits and simulations for the remaining SV surveys) and nightly observing reports.
The cadence of these narrative commissioning updates might be reduced in the coming weeks as the Observatory directs effort towards generating other tooling and report mechanisms to describe survey progress (as above). Major activities and milestones will continue to be reported throughout the on-sky commissioning campaign.
If there’s no transmission to the MPC then what are my possibilities to know about an identification of a dwarf planet during the SV Survey ??
: I am not professional and don’t have access to the Rubin Science Platform…
