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. 

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.

Flexure effects within GMOS can result in wavelength zeropoint shifts if the on-sky science data are wavelength-calibrated using daytime CuAr arc exposures.