Session Parameters

 

Table 7.6: Command parameters (1)

Parameters: CALIBRATE command (See also next table)
Parameter	Description
INSTR	Defines the spectrograph (e.g. CASPEC, EFOSC).
GRATING	Defines the grating or instrument configuration.
CCD	Defines the CCD.
CCDBIN	Binning factor along X and Y. This parameter has impact on the wavelength calibration.
SCAN	Limits of the scanned area of the CCD. This parameter has impact on order definition (method Hough) and background estimates.
ORDREF	Order reference frame
DEFMTD	Order definition method ( STD, COM, HOUGH).
DEFPOL	Degree of the bivariate polynomial used in the definition of the orders, see Section 7.2.
WIDTH1	Defines the width in pixels of the orders perpendicular to the dispersion direction. It is used to detect the orders as described in Section 7.2 (methods STD, COM). Typical values are between 2 and 15, depending on the observing slit.
THRES1	Defines the threshold to detect orders on the order reference image as described in Section 7.2 (methods STD, COM).
SLOPE	Mean slope of the orders in pixel space (methods STD, COM).

 

 

Table 7.7: Command parameters (2)

Parameters: CALIBRATE command (Continued)
Parameter	Description
NBORDI	Number of orders to be detected (method HOUGH).
WIDTHI	This parameter is used to remove the traces of the orders in Hough space during the detection. Its minimum value is the half-width in pixels of the orders perpendicular to the dispersion direction. Its maximum value is the interorder distance minus the half-width of the orders (method HOUGH).
THRESI	Defines the threshold for the order detection (equivalent to THRES1)
WLC	Raw wavelength calibration image.
LINCAT	System table with comparison lines.
EXTMTD	Extraction method ( AVERAGE, LINEAR, OPTIMAL).
SLIT	Width of the extraction slit in pixels.
OFFSET	Offset of the extraction slit. The offset is given in pixels, positive values are above the center and negative offsets are below the center of the orders as shown in the image monitor (command LOAD/ECHELLE).
SEAMTD	Searching method ( GAUSSIAN, GRAVITY). This parameter controls the definition of the center of the calibration lines.
WIDTH2	Defines the width of the calibration lines in pixels.
THRES2	Defines the threshold above the local background to detect comparison lines. The actual value should be chosen to detect about 10 to 20 lines per order.
WLCMTD	Wavelength calibration method ( PAIR, ANGLE, TWO-D, GUESS, RESTART, ORDER). This parameter controls the execution of IDENTIFY/ECHELLE.
WLCOPT	Dispersion relation option (1D, 2D)
GUESS	Optional reference to a previous session with the same instrument configuration, to be used as a guess for the dispersion coefficients (required if WLCMTD=GUESS).
WLCVISU	Visualisation of intermediate results (YES/NO).
DC	Is the degree of the polynomial used in the dispersion relation, see Section 7.6.
TOL	Defines a tolerance window for the last step of single-order computation of the dispersion relations.
WLCLOOP	Three parameters to control the iterative identification of lines by improvement of a global solution. WLCLOOP(1) = Minimum initial accuracy of the solution (pixels) WLCLOOP(2) = Tolerance on the distance of the nearest neighbours. A value of e.g. 0.2 means that the nearest neighbour must be found at least at 5 times (=1/0.2) the residual to confirm the identification. Optimal values of this parameter are in the range 0. to 0.5. WLCLOOP(3) = Maximal allowed accuracy of the loop.
WLCNITER	Two parameters for the minimum and maximum number of iterations of the identification loop.

 

 

Table 7.8: Command parameters (3)

Parameters: FLAT command
Parameter	Description
FFOPT	Flat-Fielding option ( YES/NO). If the value NO is assigned to this paramter, no Flat-Field correction is performed
FLAT	Raw flat field image.
CORRECT	Flat field correction image.
BLAZE	Smoothed flat field used in the normalisation of the flat field.
BKGMTD	Background estimation method ( POLY, SPLINE, SMOOTH).
BKGVISU	Visualisation of intermediate results ( YES/NO).
BKGSTEP	Step in pixels of the grid of background reference positions.
BKGPOL	Degree of the bivariate polynomial for background fiting (method POLY).
BKGRAD	Radius (radx, rady) in pixels of the window for local estimate of the background. The window is parallel to the orders (radx is measured along the orders, rady is parallel to the columns). (method SPLINE)
BKGDEG	Degree of spline polynomials (method SPLINE).
BKGSMO	Smoothing factor for smoothing spline interpolation. See Section  7.4 (method SPLINE).
EXTMTD	(See definition in Table 7.7)
SLIT	(See definition in Table 7.7)
OFFSET	(See definition in Table 7.7)
SAMPLE	Defines the wavelength step of the spectrum sampled in wavelengths. It can either be a real number indicating the step in units of Ångstrøm or a reference file corresponding to an image sampled in the space order-wavelength.
Parameters: FILTER command
Parameter	Description
BKGxxx	All background parameters : see definitions above.
MEDFILT	widx,widy,no_iter. See help of command FILTER/ECHELLE.
CRFILT	radx,rady,mthresh.
CCDFILT	read-out noise (in e-), inverse gain factor (e-/ADU), threshold (in units of standard deviation).

 

 

Table 7.9: Command parameters (4)

Parameters: RESPONSE command
Parameter	Description
STD	Raw Standard star, in STANDARD reduction mode.
RESPONSE	Computed instrument response in STANDARD reduction. If the name NULL is assigned to this parameter no response correction is applied in the REDUCE command. Instead, the blaze function is fitted.
FLUXTAB	Table with absolute fluxes for the Standard star, in STANDARD reduction mode. The tables are in the area MID_STANDARD
FILTMED	Radius in x and y, threshold, as in command FILTER/MEDIAN used to smooth the response function.
FILTSMO	Radius in x and y, threshold, as in command FILTER/SMOOTH used to smooth the response function.
PIXNUL	Number of pixels to set to zero at the edges of each order.
BKGxxx	All background parameters : see definitions in Table 7.8)
FFOPT	Flat-Fielding option ( YES/NO)
CORRECT	Flat field correction image (required if FFOPT=YES).
BLAZE	Smoothed flat field (required if FFOPT=YES).
EXTMTD	(See definition in Table 7.7)
SLIT	(See definition in Table 7.7)
OFFSET	(See definition in Table 7.7)
SAMPLE	(See definition in Table 7.7)
Parameters: REDUCE command
Parameter	Description
BKGxxx	All background parameters : see definitions in Table 7.8)
FFOPT	Flat-Fielding option ( YES/NO)
CORRECT	Flat field correction image (required if FFOPT=YES).
BLAZE	Smoothed flat field (required if FFOPT=YES).
EXTMTD	(See definition in Table 7.7)
SLIT	(See definition in Table 7.7)
OFFSET	(See definition in Table 7.7)
SAMPLE	(See definition in Table 7.7)
RESPOPT	Option for the response corection ( YES/NO).
RESPMTD	Method for the instrumental response correction ( STD, IUE).
RESPONSE	Name of the response image as produced by RESPONSE/ECHELLE (required if RESPMTD=STD).
RIPMTD	Defines the ripple correction algorithm as SINC for the method fitting the blaze function, described by Ahmad(1981), and as OVER for the method using the overlapping region of the orders, proposed by Barker (1984) (required if RESPMTD=IUE).
RIPK	Defines the initial guess for the parameter k in Equation 7.5. The default value is updated during the wavelength calibration.
ALPHA	Defines the initial guess for the parameter $\alpha$ in Equation 7.5.
MGOPT	Merging option ( YES/NO).
MRGMTD	Merging method ( AVERAGE, NOAPPEND).
DELTA	Interval (in wavelength units) to be skipped at the edges of each order.