Doc:
Issue
Date
Page
VLT-MAN-ESO-14650-4942
P96
24.06.2015
45 of 161
ESO, Karl-Schwarzschild-Str. 2, 85748 Garching bei München, Germany
The figures below for the 0.9” and 0.6” slits with/without filter show the different noises at
different wavelength taking into account all the sources of background noises:
thermal background, RON, sky background, dark current.
The black curve corresponds to the RON. The back dashed curve corresponds to the dark
current. The dashed color curves correspond to the measurements at different wavelength
for the slit without filter, the normal color curves correspond to the measurements at different
wavelength for the slit with filter.
A Background with 0.9” slits with/without filters
a) For 0.9” slit with K-band blocking filter:
Unfortunately, the background is always RON limited for DIT shorter than 1000s
whatever the wavelength is for this slit with filter despite a strong decrease of the
RON. For DIT longer than 1000s, the background is sly limited at least at the
1682nm.
b) For normal 0.9” slit without filter:
For this slit, the background is RON limited for DIT up to 200s-300s at
wavelengths 1682nm and 1300nm. Then for longer DIT the background is sky
limited.