This plot shows the IRDIS DBI background in ADU/sec.
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<ul>
<li> (1) negligible background in the H-band (no ND filter)
<li> (2) stable background for the K-band
<li> (3) no background for H-band plus neutral density filters
<li> (4) K-band background correlates with the temperature of the neutral density filters. 
Both temperature values (red and green little dots) are given in [C] and have been scaled via:
<br>T(in the plot) = 1.452 T - 1.409<br> to fit the background rate values given in
[ADU/sec].

</ul>

Note for (4): The neutral density filters (here ND_1.0 and ND_2.0)
used for IRDIS are located in the CPI. The same background is measured
for both ND filters, hence it is independent on the ND filter throughput. 
The background is correlated with the CPI temperature.