## WFC Parallel EPER

Old coefficients are given in Table 2 of ACS ISR 2005-03. Below is the table with the new coefficients. MJD limits are defined such that MJD1 <= MJD < MJD2. The discontinuities are an educated guess based on known temperature changes and observed CTE trends. Their fits are shown in the plots to follow.

MJD1 | MJD2 | n | c | p | Notes about MJD2 |
---|---|---|---|---|---|

52335 | 53552 | 8.086x10^{-5} |
2.329x10^{-6} |
-5.799x10^{-1} |
Aft shroud temperature test |

53552 | 53918 | -5.520x10^{-4} |
2.569x10^{-6} |
-5.616x10^{-1} |
-77C to -81C; Switched to Side-2 |

53918 | 58849 | -6.947x10^{-4} |
2.739x10^{-6} |
-5.532x10^{-1} |
A distant future |

#### CTE vs Signal

Here are the fit residuals:

Here is the legend:

#### CTE vs Time

"Problematic" point is as re-defined by M. Mutchler during SM4 SMOV (2009; private communication) based on initial prediction in ACS-R Multi-Parameter Optimization Constraints (ACS TIR 2008-04).

Here are the fit residuals:

Here is the legend:

#### These are no longer good fits

Least-square straight lines do not fit so well anymore without having to break the data into separate segments as above.

Here are the fit residuals for the plot above:

Predictions using fits from ACS ISR 2005-03 do not fit post-SM4 data well.

Here are the fit residuals for the plot above: