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.

The 2025B Gemini Observatory Call for Proposals has been released. Proposals are being accepted for observations from 1 August, 2025 to 31 January, 2026. Gemini North and Gemini South are expected to have 128 and 159 nights available for science, respectively. A new version of the Phase I Tool (PIT) has been released to support proposal submissions.

The 2025A Gemini Observatory Call for Proposals has been released. Proposals are being accepted for observations from 1 February, 2025 to 31 July, 2025. Gemini North and Gemini South are expected to have 165 and 155 nights available for science, respectively. A new version of the Phase I Tool (PIT) has been released to support proposal submissions.

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

The 2024B Gemini Observatory Call for Proposals has been released. Proposals are being accepted for observations from 1 August, 2024 to 31 January, 2025. Gemini North and Gemini South are expected to have 153 and 157 nights available for science, respectively. A new version of the Phase I Tool (PIT) has been released to support proposal submissions.

Letters of intent are now solicited for new Gemini Large and Long Proposals, to begin in semester 2024B. Letters are due by February 12 2024, and full proposals by April 1 2024.

GMOS-S will be removed from the telescope on Friday, July 21st for the CCDs intervention, with the purpose of replacing the faulty CCD2.
The instrument is scheduled to come back during late August for the commissioning of the upgraded detector array, and expected to be available for Science by September.
 

The GMOS-N B600 grating sensitivity has recently degraded significantly. This overall degradation is in addition to the blue sensitivity loss reported previously. Since the new B480 grating is now available for GMOS-N, we recommend changing B600 programs to the B480 grating. The B480 grating offers a wider wavelength coverage than B600 at a a slightly reduced spectral resolution.

The 2023B Gemini Observatory Call for Proposals has been released. Proposals are being accepted for observations from 1 August 2023 to 31 January 2024. Gemini North and Gemini South are expected to have 162 and 141 nights available for science, respectively. A new version of the Phase I Tool (PIT) has been released to support proposal submissions.

After the GMOS-S detector troubleshooting earlier this semester, the physical location of the array has shifted by a small amount in the -direction. While this did not have harmful consequences, the Y-shift has the effect of the MOS mask slits as defined on the MDF appearing with a small (~20 pix) yet systematic offset with respect to the actual location of the spectra.