LUCI2 G200 Available – problem understood! (June 28, 2024)
The G200 tilt issue is now understood. The “in position” switches turn on just before the grating wheel engages the detent. With a few dropped steps this can leave the grating wheel out of position, though the software thinks it is correct. It won’t be possible to fix this until the next time LUCI2 is opened, but it should be reliably correctable.
Recovery requires LBTO personnel to move the grating wheel motor +10 steps to bump it into the detent. Calibrations have been updated. I don’t consider this shared risk anymore.
LUCI2 G200 Available – shared risk (June 25, 2024)
We are releasing the G200 grating in shared risk for science observing. While the problem described below persists and we continue to investigate, it seems to work most of the time and there is a workaround we can try if it is out of position. This requires involvement of the LBTO support person assigned to your run as it involves working with the low-level LUCI engineering GUIs, so please notify them if you plan to use the G200 grating.
LUCI2 G200 Unavailable (June 2, 2024)
An issue was noted with the G200 calibration during checkouts. While this is being investigated the G200 will remain unavailable for science. All other modes are released.
LUCI2 Commonly Used Modes Released for Science (May 30, 2024)
The G200 with the N1.8 has completed calibration. The repairs to the tilt sensor recently made appear to have resolved the issues experienced with the G200 tilt sensor, and it now is reliably going to the requested wavelength. N375 Imaging, N375 & N1.8 G210, and N1.8 G200 are released for science with the following caveats:
- The existing flexure and wavelength calibration tables remain in place for the G210. The risk from operations without these recalibrations/checks is expected to be low since the disassembly for the repairs was minimal.
- The less commonly used mode of N375 G200 spectroscopy is pending flexure recalibration.
The AO system has been checked out and a first pass of NCPA tables has been generated. The NCPA amplitude has changed with the recent thermal cycling and further work is needed to refine the NCPA tables. Work is underway to improve these NCPA coefficients. Full AO for bright sources remains unavailable until these tables are refined. ESM is fully available in all modes.
LUCI2 Installed and Released for Science with Caveats (May 24, 2024)
LUCI2 was installed on the telescope on May 23rd. The functional checkout on the telescope was successful. The instrument was released for Imaging with the N375 and spectroscopy with the G210 N1.8 on May 24th with the following caveats:
- The G200 remains unavailable pending recalibration and checks
- The existing flexure and wavelength calibration tables remain in place for the G210. The risk from operations without these recalibrations/checks is expected to be low since the disassembly for the repairs was minimal. Images taken support this
- AO checks are underway for FULL AO. ESM has been released for science.
LUCI2 Removed for repairs (May 7, 2024)
LUCI2 was removed from the telescope for repairs on May7th. The repairs will take place in the lab over the next week with an expected reinstall date of May22 and return the instrument for science readiness around May 28th.
LUCI2 Schedule Repairs (Apr 29, 2024)
LUCI2 is schedule for removal from the telescope on May 7th or 8th for repairs to the G200 Grating. Testing has shown that the problem lies within the LUCI2 instrument, with the LUCI2 tilt sensor. This intervention was deemed necessary for instrument safety and longevity.
This intervention will address the LUCI2 tilt sensor, with plans to reinstall LUCI2 around May 22nd and return the instrument for science readiness around May 28th.
LUCI2 G200 Displaced Spectra (Apr16, 2024)
The LUCI2 G200 grating has been having increasing trouble reliably reaching the central wavelength requested. Users/observers should frequently check the grating position for both science and calibration exposures by comparing to known good data or between LUCI1 and LUCI2. Troubleshooting notes and recovery suggestions have been added to the LUCI pages (here). If the problem persists after trying to recover, it may be necessary to switch to programs not using G200. The problem could be in the external electronics or the internal tilt sensor at the grating. Testing to determine this should be done in the next few weeks.
Note that the G210 grating is unaffected by this problem. Programs using the G200 grating in LUCI2 could be redesigned to use G210 instead, with the obvious trade-off of higher reliability of G210 vs. extra time to observe two bands for programs that require the full wavelength coverage.
