GNIRS recently began showing an issue that affects every 8th column on the top right quadrant of the detector, an issue that impacts all GNIRS modes. This issue first appeared on the 25th of October, 2022. Investigations to mitigate or fix the issue are currently ongoing. For the time being, PIs are advised to consider all pixels associated with these columns as bad pixels and not to use them for science and/or calibrations.
The figures below show a flat taken in Cross Dispersed Mode with the 32l/mm grating. The impact of noisy columns is highlighted by the horizontal projection crossing the 8th order.
An updated bad pixel mask that masks every 8th column in the upper right quadrant in addition to the previously known bad pixels can be downloaded here. Note that this bad pixel mask is for use with Gemini IRAF, the equivalent BPM has been archived for DRAGONS.
Note that for data taken later than April 22nd, 2024, this issue is now fixed (see the announcement here).
