EIS continues calibration operation (eg. REGCAL071
/REGCAL072) to generate hot and warm pixels maps for EIS_PREP routine use: e.g. to mark the hot/warm pixel positions and smooth the values on those positions.
The hot/warm pixels maps are distributed with SolarSoft under hinode/eis/data/cal branch.
Before EIS launch, the CCD read-out section was assumed in the middle 512 rows of the CCD. That means EIS_PREP only needs hot/warm pixels maps of middle section of CCDs.
However, in post-launch phase, the top and bottom of the CCDs were introduced to cover whole CCDs area (ie. Y-axis: 0-1023 rows, X-axis: 0-4095 columns). Thus hot/warm pixels maps for EIS CCDs have been generated accordingly as top and bottom maps (in detail: REGCAL072 study for top of CCDs and REGCAL071 study for bottom). The EIS_PREP routine has also changed in order to use top and bottom hot/warm pixels maps.
The EIS camera electronics do not readout CCD row 0 in the y-direction (this is due to how the electronics work, row 0 is always discarded), so for the bottom of the CCDs EIS camera readout from row 1 to row 512 (inclusive), and for the top the camera readout from row 512 to row 1023 (inclusive).
So we can see there is an overlap at the 512th row, ie.:
| Bottom half: | row 1 -- row 512 |
| Top Half: | row 512 -- row 1023 |
"The overlapping row (512) is there because the MDP requires that data to be a multiple of 8 in both the X and Y directions. Rows 1 to 511 is not a multiple of 8, hence we have to read rows 1 to 512 (inclusive). For the top half we must read 512 for 512 (i.e. rows 512 to 1023), hence the overlap in row 512."
-- Jian Sun (2008-10-17)