Analysis of Alternating Exposure Mode Data

Alternating exposure mode results

Date	ObsID	I-array CTI		S3 Rejects		Linear Fit
		(x 10^-5)		(cts/frame)		Intercept	Slope
		3.2 sec	4.0 sec	3.2 sec	4.0 sec	(x 10^-5)	(x 10^-7 /(cts/frame))
28 Mar 2000	62102	12.13 ± 0.07	11.93 ± 0.06	57.2 ± 0.3	68.8 ± 0.3	13.1 ± 0.6	-1.7 ± 0.8
18 Sep 2000	61919	12.75 ± 0.07	12.62 ± 0.06	43.3 ± 0.3	51.9 ± 0.2	13.4 ± 0.6	-1.5 ± 1.1
26 Sep 2000	61907	12.51 ± 0.08	12.44 ± 0.06	50.9 ± 0.3	61.8 ± 0.3	12.8 ± 0.6	-0.6 ± 0.9
01 Mar 2001	61720	12.65 ± 0.08	12.48 ± 0.06	53.6 ± 0.3	64.1 ± 0.3	13.5 ± 0.6	-1.7 ± 0.9
28 Aug 2001	61492	12.97 ± 0.08	12.93 ± 0.07	51.1 ± 0.2	59.6 ± 0.2	13.3 ± 0.7	-0.6 ± 1.2
31 Jan 2002	61327	13.00 ± 0.08	12.95 ± 0.07	54.8 ± 0.2	63.7 ± 0.2	13.4 ± 0.7	-0.7 ± 1.1
19 Jul 2002	61114	12.98 ± 0.08	12.88 ± 0.07	61.3 ± 0.2	72.7 ± 0.3	13.5 ± 0.7	-0.8 ± 0.9
03 Feb 2003	60861	13.23 ± 0.08	13.09 ± 0.06	55.3 ± 0.2	65.4 ± 0.2	14.0 ± 0.7	-1.4 ± 1.0
16 Jul 2003	60647	13.39 ± 0.07	13.28 ± 0.05	55.1 ± 0.2	66.0 ± 0.2	13.9 ± 0.5	-1.0 ± 0.8
17 Aug 2003	60585	13.45 ± 0.07	13.31 ± 0.05	55.4 ± 0.2	66.2 ± 0.2	14.2 ± 0.5	-1.4 ± 0.8
24 Feb 2004	60358	13.38 ± 0.08	13.29 ± 0.06	60.6 ± 0.2	71.6 ± 0.3	13.9 ± 0.7	-0.8 ± 0.9
26 Mar 2004	60305	13.26 ± 0.10	13.17 ± 0.08	62.5 ± 0.3	75.2 ± 0.3	13.7 ± 0.7	-0.7 ± 1.0
Mean fit						13.58 ± 0.18	-1.11 ± 0.27

Methods for using alternating exposure data to determine rate of CTI increase

Current CTI detrending uses a weighted mean of the slope fit to each of the alternating exposure mode observations, i.e. -1.11 x 10^-7 CTI / (S3 rej / frame).
CTI increase = 3.35 ± 0.07 x 10^-6 / year (2.48%) (as of 04/02/2004)
The intercept of the linear fit to each alternating exposure mode data is a measure of the mean I-array CTI in the absence of background at the time of the measurement. The slope of the CTI/background relation is a free parameter for each ObsID.
CTI increase = 2.5 ± 1.3 x 10^-6 / year (1.9%)
Fixing the detrend slope to it's mean value (-1.11 x 10^-7 CTI / (S3 rej / frame)), the intercepts can again be used to measure I-array CTI in the absence of background.
CTI increase = 3.0 ± 0.3 x 10^-6 / year (2.3%)