2025-11-28 Early Operations Update

News
#1

Week 5 of Early Operations

A theme for the week has been characterizing the convergence and stability of the Active Optics System (AOS) closed loop control system in multiple modes. First, the team ran stability tests at a fixed telescope orientation with many iterations of closed loop corrections in a scripted mode. Next, the team ran the AOS in survey mode with observations driven by the Feature Based Scheduler (FBS) using a highly simplified survey configuration with fixed telescope pointing, and periodically perturbing the optics to study the AOS closed loop response. The team is using the data to tune the performance of the proportional-integral-derivative (PID) controller used by the AOS closed loop and optimize the gains for stable and efficient convergence. The team will run successive versions of this test with increasing complexity until approximating full survey operations.

Towards the end of the week, the team began a planned multi-night test running the pre-LSST survey with the Feature Based Scheduler (FBS) for full nights in a “constrained mode” with limits imposed on the physical rotator angle range and elevation angle range, and using only a single filter throughout the night. The objective is to help disentagle contributions of the delivered image quality while observing in a wide-area survey mode, in particular, characterizing the performance of the AOS closed loop for short slews and smooth changes in the optical state, and limiting abrupt visit-to-visit changes that are more diagnostic of the AOS open loop performance.

Earlier in the week, the team completed a fourth epoch of Target of Opportunity (ToO) observations for 251112cm, concluding the planned Rubin ToO observations for this event.

Other on-sky tests included validation of a pointing model update and continued validation of the filter focus offset look-up table (LUT).

Six dome louvers are now qualified for nighttime operation.

The u filter was swapped out in exchange for the y filter on 25 November, such that the currently installed filter set is grizy.

#2

Great to see the continued progress on AOS closed-loop stability, PID gain optimization, and the constrained-mode FBS survey tests. These results are highly relevant to the performance of small-body detection pipelines.

My current work focuses on a focal-geometry orbital classifier and a curvature-based diagnostic for distinguishing solar-system and interstellar trajectories from short-arc tracklets. Because the method operates prior to orbit fitting, it may complement early-operations evaluation of astrometric stability, short-arc linking, and non-sidereal detection sensitivity.

For context, I recently posted a proposal describing a lightweight focal-geometry and curvature classifier (FGOC) designed for DIASource-level prompt processing:

FGOC produces deterministic geometric–curvature features (<1 ms per arc) without modifying any existing AP/MOPS logic, and may offer a complementary perspective for characterizing early-ops astrometric behavior or tracklet dynamics.

If there is interest, I would be happy to provide a concise technical summary or benchmark examples for possible assessment during early-ops testing.