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Post-SM4 Internal CTE for WFC

WFC Serial EPER

EPER serial CTE has worsened a bit but is <10% of its parallel counterpart. Discontinuity in Amp A, which was mentioned in ACS ISR 2005-03, is still present. There is some evidence suggesting chip dependence, also mentioned in the ISR.

ACS ISR 2005-03 did not publish coefficients for EPER Serial CTE. Below is the table with the new coefficients. MJD limits are defined such that MJD1 <= MJD < MJD2. There is a hint of discontinuity around the time of -77C to -81C temperature change, especially for WFC2, but a continuous straight line still fits pretty well for now. Their fits are shown in the plots to follow.

MJD1 MJD2 Chip n c p Notes about MJD2
52335 58849 WFC1a 2.589x10-5 6.367x10-8 -4.265x10-1 A distant future
WFC2b -3.912x10-6 2.852x10-8 -3.636x10-1
a Amps A and B. For A, only <3000e used.
b Amps C and D.

CTE vs Signal

WFC1:

WFC2:

Here is the legend:

CTE vs Time

WFC1 (Amp A ~7200e data are shown but not used):

WFC2:

Here is the legend: