LBC
During SSD, the filters and accessible lenses were cleaned, and the TMS collimators were reinstalled and realigned. A software service was put in place to simplify operation of the LBCs with TMS.
During restart, the LBCs were run through tests, checking for gross focal-plane tilt, running science-like scripts that dithered and guided, and executing non-sidereal observations. Photometric standard star fields were also observed, results of which will be made available soon.
The LBCs are fully checked out and ready for science.
MODS
During SSD, all of the mask frames were replaced by new ones with steel stow sensor targets that enable a larger sensor gap which will reduce the risk of collisions like those which occurred during the 2021B and 2022A semesters. Rick Pogge & Mark Derwent (OSU) inspected the slitmask cassettes and optics as well.
During restart, tests were made to ensure that the instruments were aligned at the focal station, and science-like and spectrophotometric and photometric standard star scripts were run which used all modes. Standard star data are being reduced and the results will be made available soon. The instruments are ready for science with the following caveats: 1) a problem which emerged with the MODS1 Blue IMCS, where one or more quad cell readings would be 0 causing lock to fail, is still being worked on. This problem appeared only once during on-sky checkouts. And 2), another issue which was first seen in early 2022 has reappeared: a variable bias level in one of the readout channels in the lower right quadrant of MODS1B. The prescan can be used to correct for this in the full frame (8K x 3K) 2D spectra, but the smaller readout regions used by imaging and prism modes do not have a prescan. It is recommended to avoid placing targets or spectra in the lower right quadrant when possible. The chronic problems of long, ~100-sec, readout delays, which affect a fraction (10-20%; to be confirmed) of MODS1R and MODS2B images, remain.
LUCI
Please see LUCI1 and LUC2 2023B restart delays for details
The work on LUCI1 is wrapping up and it will start cooling in the lab next week. Immediately following its installation on the telescope, LUCI2 will be moved in to the lab for repairs to address the leak discovered at the end of SSD 2023B.
LUCI1 and LUCI2 are unavailable for science at this time.
PEPSI
See PEPSI upgrades And Work Status SSD23 for details about the recent PEPSI overhaul. PEPSI Camera focus has been determined. A full CCD report is being generated. The CCD gain is 2.3 e/ADU on average. We aligned on sky and took several spectrophotometric standards. Ilya reviewed and found the results are good. He is actively updating the ETC with the results. PEPSI is released for science.
