It was recently reported that the observed counts in spectra seemed to be lower than expected on CCD1 for some programs - also, odd emission-like features (‘spikes’) were noticed in the CCD1 portion on stellar spectra that are known to be featureless.  All this applies only to data acquired during the ‘bad-CTE’ periods of CCD1, i.e. between:

• 2020 Oct 24 - 2021 April 05
• 2019 dec 18 - 2020 March 14
• 2019 april 11 - 2019 June 24
• 2018 May 14 - 2018 May 28 
• 2018 april 15 - 2018 April 27

PIs with GMOS-S data observed during any of these periods are encouraged to assess whether this had a negative impact. PIs can look in the archive to identify the dates for which their data was taken at https://archive.gemini.edu/searchform/cols=CTOWEQ/notengineering/GMOS-S/NotFail/not_site_monitoring/progid=GS-20XYZ-Q-XXX 
(replace XY with the year and Z with the semester and the XXX with the program ID)

Currently, CCD1 is operating OK since the issue disappeared as of April 05, 2021.