Science News
MODS Controller Upgrade
Posted Aug 19, 2025
MODS Controller Upgrade – Instrument Availability Delayed
update: Nov 26th
The MODS instruments underwent controller upgrades this summer, replacing the legacy head electronics and a set of aging computers. These upgrades were carried out to ensure the long-term reliability, robustness, and stability of the instruments. Additionally, preliminary testing shows a significant reduction in readout overheads.
Significant progress was made on the controller configuration while both MODS were off the telescope for the PEPSI-POL block, and both MODS will remain in the high bay while this work continues. They are scheduled to be mounted in the second week of December. Some time will be required for on-telescope testing and verification before they can be released for science, possibly in the second half of December.
MODS2 Mask Cassette Issues
Posted Jun 28, 2025
On the night of June 26 UT when moving the 2.4″ longslit into the focal plane, the mask failed to insert into the focal plane despite the software thinking so. When the instrument was opened, the grabber was found to be in the FPU but the mask was still in the cassette. Further tests showed the same issue at the same telescope/instrument orientation (EL=40 deg., instrument rotation=238 deg.). A temporary solution was found by removing all of the custom masks in slots 13-24 and placing the 2.4″ long slit mask into position 24, after which it was inserting into the FPU without issue.
MOS Mask Milling Machine Issue – Resolved
Posted Apr 10, 2025
April 11, 2025: Problem with the oxygen regulator was found and resolved. The MOS mask milling machine has been returned to operation.
April 9, 2025: The laser for the MOS mask milling machine recently stopped working. Currently all mask milling for LUCI and MODS is halted while the issue is resolved.
LUCI1 Filter Wheel#2 (Broadband) Switch Issue
Posted Apr 03, 2025
Apr 2, 2025: Flaky switch on LUCI1 Filter Wheel #2 (broadband filters).
LUCI1’s Filter Wheel #2, where the broadband filters are located, is showing a flaky position sensing switch that affects all higher-numbered filters, which includes all but the zJspec and J filters. LBTO assistance will be needed to safely drive LUCI observations until this gets repaired.
LUCI1 Critical MOS error Recovery Status
Posted Mar 09, 2025
Mar 13, 2025: All normal modes with LUCI1 are released for science.
N375 and N30 imaging, as well as G210 and G200 spectroscopic modes have all been released for normal science use.
Mar 9, 2025: LUCI1 All modes **NOT** using G210 or G040 are released for science.
LUCI recalibration is underway. All modes **NOT** using G210 or G040 are released for science.
LUCI1 is working well mechanically and all the major modes have new flexure tables. In G210 there is still an issue with the wavelength calibration which is being investigated and reviewed.
Feb 13, 2025: LUCI1 Troubleshooting/Cooling in the lab
Maintenance work and testing continued through the month of January.and beginning of February. The MOS translator issue was addressed, as well as issues with the LUCI1 grating turret. Other general maintenance items were also taken care of while the instrument was disassembled. LUCI1 has passed a full warm checkout and is now cooling in the lab.
Jan 06, 2025: LUCI1 Lab Troubleshooting
LUCI1 troubleshooting in the lab is ongoing. The MOS unit is now able to reliable move the mask with the unit warm. Several motors are scheduled for replacement.
Dec 30, 2024: LUCI1 Removed from telescope
The MOS troubleshooting revealed an issue internal to the instrument. LUCI1 was removed from the telescope to allow for continued troubleshooting and repairs in the lab.
Dec 9, 2024: LUCI1 Offline with MOS error
LUCI1 experience a critical MOS error on December 09, 2024. LUCI1 taken offline for troubleshooting.
SX ASM Status Update
Posted Feb 14, 2025
Update Feb 24, 2025
On-sky seeing limited checkouts were completed on UTFeb24. The binodal astigmatism was measured and collimation tables updated. The SX ASM is released for all available seeing-limited science modes without restrictions.
Update Feb 14, 2025
ASM and AO calibration and checkout teams were able to swiftly integrate, calibrate, and checkout the unit for SHARK-NIR science. The SX AO has been released for shared-risk SHARK-NIR science.
LUCI1 remains off the telescope (see here for details). The AO team is working to test the SX LUCI WFS and SX ASM with IRTC1 in place of LUCI1 to ensure the system is ready when LUCI1 becomes operational.
Modes available for shared-risk release include:
- SX PEPSI PFU
- MODS1 Longslit Spectroscopy
- SHARK-NIR AO
Wide field imaging and MOS spectroscopy remain unavailable pending the measurement of the field aberration.
Update Feb 08, 2025:
The TS5 was partially realuminized to recoat the impacted area on Jan 25, 2025 and reintegrated with the SX ASM on Jan 31, 2025. After passing lab tests, the unit was installed on the telescope on Feb 07, 2025. The flat was verified for seeing limited operations and the unit was released for seeing-limited shared-risk science.
The science modes available for shared risk seeing limited science include SX PEPSI PFU, and MODS1 for longslit spectroscopy with the caveat that sources may not be optimally collimated. MODS imaging and MODS MOS Spectroscopy should wait until we can execute the field aberration work. LUCI1 is pending installation on the telescope (see note here for details).
Update Jan 09, 2025:
Several actuators were replaced on the SX ASM. TS5 recoating operation is scheduled for the week of January 20 at Sunnyside. The ASM team is preparing SX ASM to integrate with the recoated TS5 the week of January 27.
Update Sept 20, 2024:
Assessments by the AO team have revealed that the rear-side surface of the SX thin shell (TS5) suffered significant water damage that will very likely require recoating. Planning for recoating the thin shell is happening now and the optimistic timeline is that this would enable the SX ASM to return to service sometime in November. The AO team has now shifted efforts to the DX ASM.
Update Sept 9, 2024:
The preliminary inspection by the ASM team shows signs of watermarks and possible burns in one of the distribution boards. After disconnecting the affected board, the team powered on the rest of the unit and measured the gap for all but ~ 6% of the thin shell’s area. The measurements suggest that the water intrusion is receding (leaving the gap), which is encouraging. The team will thoroughly assess the water damage when they lower the thin shell, which is expected around September 17.
Initial Note: Sept 2, 2024
On UT Sept 1 the telescope experienced a water intrusion event. The SX ASM thin shell had liquid gap contamination impacting the outer rings between 7-9 O’clock. The unit was removed on Sept 2 for repairs. The timeline for repairs is TBD.
The rigid secondary remains installed in place of the DX side while the DX ASM campaign wraps up. The SX side of the telescope will remain without a secondary mirror until the DX ASM is installed later this month.
