VLT-MAN-ESO-14650-4942
P96
24.06.2015
61 of 161
ESO, Karl-Schwarzschild-Str. 2, 85748 Garching bei München, Germany
2.4.10 NIR 11
th
order vignetting (K band)
The flux in this 11
th
order decreases towards the top of the order by a factor of ~10% and is
due to a bad design of the mask located in front of the NIR array. The same effect is present
in the blue part of the 10
th
order.
Figure 15: NIR11
th
order vignetting corresponding to a flux decrease (arrow). Figure from L.
Christensen (technical note).
Trying to correct this vignetting would imply a major operation on the NIR arm with possible
risks to degrade much more the NIR performances than they currently are.
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