Throughput measurements in preparation for the switchover to the new GMOS-N R400 grating on August 1st, 2025 (HST) confirm the improved throughput of the new grating compared to the current GMOS-N R400 grating.
The GMOS-N B480 grating is available again for scientific use after successful servicing of the bearings and springs that secure the grating in its holder.
The current R400 grating—one of GMOS-N’s most frequently used—is as old as the instrument itself, and the GMOS-N team has noted significant throughput degradation.
The spring and bearings securing the GMOS-N B480 grating within its frame have not been functioning properly and need replacement. The net effects have been possible wavelength zeropoint shifts depending on the gravity vector. These shifts have not been a major concern for science quality, since they can typically be calibrated out via the on-sky arcs or via skylines, per these instructions.
We are pleased to announce that the first observing block using the new facility instrument IGRINS-2 at Gemini north has been successfully completed. Data has been reduced using the custom IGRINS Pipeline Package (see this page for details) and is now available to PIs on the Gemini data Archive.
GHOST has returned to service following the successful replacement of the ThAr arc lamp in GCAL. Arc counts have returned to normal, and the instrument will be offered again starting tonight (2025-03-26 UT).
Important information for PIs:
A degradation in the arc lamp was identified beginning around 2025-02-13 UT, which affected the wavelength calibration of data taken during that period.
GHOST is currently unavailable due to the replacement of the ThAr arc lamp. Troubleshooting began on Tuesday, Mar 25, and is still ongoing.
A sudden drop in arc lamp intensity was identified starting on Feb 13, which has continued to decline over time. This degradation has affected the wavelength calibration, introducing uncertainties in the data.
PIs of GHOST programs taken between Feb 13 and now are advised to use arc images acquired before Feb 13 for wavelength calibration.
Seven lens interfaces in the GMOS-N collimator were refilled with index-matching oil on 5 March 2025 HST. This work was performed to address the known recurring issue of air bubbles developing in the GMOS lens interfaces.
The air bubbles move with changes in telescope elevation and cass rotator angle and can cause a shifting partial obscuration in the lower part of the GMOS frames. This results in a limited flat fielding accuracy, particularly impacting imaging data that use the entire GMOS field of view.
We are pleased to announce that a video tutorial for setting up GHOST Phase II is now available online. Check it out here: https://noirlab.edu/science/videos/ghost
We hope you find it helpful!
MAROON-X experienced two shifts in the echelle image in 24A: the first due to an earthquake on Feb 9, 2024, and the second due to a loss of observatory power on June 13, 2024. This has impacted two key steps in the reduction process. As a result, the radial velocities from 24A based on the existing reduction are currently uncertain to ~20 m/s. All data from 24B so far seem to be within specifications. The instrument team in Chicago has been adjusting the reduction procedure with the aim of resolving this issue and restoring the nominal data quality.