This is  instrument performance plot for the extinction corrected <b>photometric
zeropoints</b> (at airmass X=0), derived from photometric standard star calibration
frames observed in <b>Y </b>filter.<br>

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<b> On 2016-11-19 new, CASU pipeline was adopted (green vertical
line), which uses revised method for calculating zeropoints. It takes
into accout DET.NDIT in the total observing time (DET.DITxDET.NDIT)
rather than DET.DIT as was done by the previous pipeline. To
bring the values to the same level, the CASU zeropoints are
corrected by <br>
"+ 2.5 * log10(NDIT)" in this plot. Only data taken with DET.NDIT=5 are plotted.</b> 

</font><p><font size="2"> The reference values for each detector are currently identical to
the median of the measured values.</font><p><font size="2">

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<b>Fig. 1.</b> <b>chip4</b>: The zeropoints for chip #4. Reference value: 26.3 mag <br>
<b>Fig. 2.</b> <b>chip3</b>: The zeropoints for chip #3. Reference value: 26.3 mag <br>
<b>Fig. 3.</b> <b>Average</b>: The zeropoints averaged over all detectors.
This view is sensitive to common changes. Reference value: 26.3 mag <br>
<b>Fig. 4.</b> <b>chip1</b>: The zeropoints for chip #1. Reference value: 26.3 mag <br>
<b>Fig. 5.</b> <b>chip2</b>: The zeropoints for chip #2. Reference value: 26.3 mag <br>
<b>Fig. 6.</b> <b>Scatter View</b>: The standard deviation of the zeropoints, obtained from the sample of all detectors.
This view is sensitive changes of individual detectors.
</font><p><font size="2">Major M1 mirror recoating events are marked with a blue vertical bar.