From e2a835d1b22e9177ac81376ea1a29e856de39a30 Mon Sep 17 00:00:00 2001 From: tguillemLSST Date: Thu, 12 Dec 2024 06:36:04 -0800 Subject: [PATCH] up --- sections/biasStability.rst | 20 +++++++++----------- 1 file changed, 9 insertions(+), 11 deletions(-) diff --git a/sections/biasStability.rst b/sections/biasStability.rst index 3d1ed0d..3af302c 100644 --- a/sections/biasStability.rst +++ b/sections/biasStability.rst @@ -1,21 +1,19 @@ Bias stability ############################################ -Bias instabilities are of 2 kinds : +Bias instabilities (typically above the 1-ADU level) are observed over a significant number of sensors for both ITL and e2v CCDs. The main issues are referred as : -#. ITL bias jumps -#. e2v 2D shapes. +#. The ITL bias jumps : large variation of the column-wise structure from exposure to exposure. +#. The e2v yellow corners : residual 2D shape of the bias even after 2D-overscan correction. These residuals depend on the acquisition sequence and of the exposure time. -Both observed in Run 6 and deeply studied. Issue 1 considered as hardware-level issue, tried to mitigate issue 2 by acquisition optimization in Run 7. +Both issues were observed and deeply studied in Run 6 EO data and deeply studied. The ITL issue is thought to be an hardware-level issue (phase shifts between Readout Electronics Boards). We tried to mitigate the e2v issue by optimizing the acquisition configuration in Run 7. -For the baseline configuration (see conclusion), three stability runs were recorded : +For the baseline acquisition configuration (see conclusion), three relevant stability runs were recorded : -#. Run E2136 : 15-s darks with long delays -#. Run E2236 : 50 15-s darks, 50 biases -#. Run E2330 : 15-s and 30-s darks with delays +#. Run E2136 : 15-s darks with some very long delays throughout the run +#. Run E2236 : 50 15-s darks, 50 biases recorded with 30-s delays between exposures +#. Run E2330 : 15-s and 30-s darks with variables delays between exposures -eo_pipe bias stability task : bias + serial overscan correction, mean of the image - -Plots +To process these runs, the eo_pipe bias stability task is used : for the ISR part, a serial ('mean_per_row') overscan correction and a bias subtraction (computed from the corresponding B-protocol run) are applied. The final data product is the mean of the per-amplifier science image over the full set of exposures of the run. Two typical examples are shown in the figures below. .. list-table::