ESO
SINFONI Pipeline User Manual
Doc:
VLT-MAN-ESO-19500-3600
Issue:
Issue 1.0
Date:
Date 2005-10-19
Page:
78 of 88
A more accurate method is described in the following and needs to be implemented.
The spectral type of the star is determined looking into a catalogue.
From this information is obtained the star energy distribution.
This curve is scaled so that the value at the central flux is
'
.
3. The result of step 1 is divided by the one from step 2. This is the efficiency.
10.1.18
Strehl computation
The central maximum in units of the total flux of a PSF is a measure of the image quality and AO performance.
The Strehl ratio is the observed ratio in units of theoretically possible (diffraction limited) ratio. It is a number
usually between
0.01 (seeing limited) and 0.6-0.8 depending on the performance and the ambient conditions.
10.1.19
Encircled energy computation
The encircled energy is the signal integrated in a given area centered on the position where the object reaches
its maximum. For this computation it is critical to estimate the flux of the background.
10.1.20
Spectrum extraction
The standard star spectrum is extracted by summing the object signal in each plane of the cube. The residual sky
background contribution is given by the constant term of a 2D Gaussian fit of the image obtained by averaging
the cube along z, in a range of factor times the mean FWHM (FWHM=0.5*(FWHM_Y)) of the
observed standard star.
10.1.21
Standard star position detection
The recipe determines the position of the maximum in the image obtained by collapsing the cube along the
z-axis. Then the STD star object (which is assumed to be the only object in the FOV) is more accurately located
using a centroid algorithm assuming a 2D Gaussian shape approximation for the object PSF, which also allows
to estimate the STD star FWHM along the X and Y directions.
10.2
Recipes
10.2.1
Detector linearity and non-linear bad pixel map determination: si_rec_detlin
The si_rec_distortion recipe computes the detector non-linearity coefficient as described in 10.1.3 (using meth-
ods 1 and 2). The detector gain is also computed as described in 10.1.5. In this way several pieces of information
are generated: a table with information on detector non-linearity (obtained with method 1), a table with infor-
mation on the gain, a cube with the coefficients of a polynomial fit to each pixel intensity which provides
pixel-by-pixel information on the detector non-linearity, a bad pixel map with non-linear pixels (the last two
products are obtained as described using method 2 as described in 10.1.3).
