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%++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
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%.COPYRIGHT (c) 1994 European Southern Observatory
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%.KEYWORDS MIDAS, help files, WLDEF/MOS
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%.PURPOSE On-line help file for the command: WLDEF/MOS
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%.VERSION 1.0 4-AUG-1994 : Creation, SM
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%----------------------------------------------------------------
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WLDEF/MOS 04-AUG-1994 SM
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WLDEF/MOS [wlc] [t,w] [ybin] [meth] [tol] [wlcord] [wlcmtd] [plotc]
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Search for lines in MOS slitlets, centers them and fits the
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WLDEF/MOS [wlc] [t,w] [ybin] [meth] [tol] [wlcord] [wlcmtd] [plotc]
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wlc = wavelength calibration image. \\
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Session Keyword: WLC \\
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t,w = threshold, window \\.
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Session Keyword: SEAPAR \\
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ybin = step, binning factor in y-direction.
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Session Keyword: YBIN \\
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meth = centering method (gaussian or gravity). \\
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Session Keyword: CENTMET \\
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Default value: gravity
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tol = tolerance for line identification\\
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(> 0 pixels, < 0 wavelength units)\\
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Session keyword: TOL\\
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wlcord = degree of fit to dispersion relation\\
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Session keyword: WLCORD(1)\\
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wlcmtd = method of fit\\
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Session keyword: WLCMTD\\
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L(inear) central wavelength and dispersion are given
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F(ors) mode for FORS observations: grism number,
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central wavelength and average linear dispersion
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C(onstant linelist) - in each slitlet the lines are
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identified for the first row and kept for the
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whole slitlet. In this mode, the dispersion
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relation may gradually evolve throughout the
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slitlet, because the dispersion relation from
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one row is used to identify the lines in the
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next row. But all lines are kept, you cannot
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throw out bad lines this way!
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V(ariable linelist) - for each row the dispersion
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relation of the first row is used to identify
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the lines and bad lines are thrown out.
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F(it all) - This mode is a combination of V and C: the
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dispersion relation may evolve gradually along the
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slitlet AND bad lines are thrown out. As this mode
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may produce rather unstable fits you should only
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use it for very good-natured data!
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plotc = plot of residuals (y or n)\\
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Session keywords: PLOTC\\
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SEARCH/MOS, CALIBRATE/MOS
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This command combines SEARCH/MOS and CALIBR/MOS. At first it
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searches the frame WLC, using the parameters threshold, window,
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binning and step in y, and centering method as giving in
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parameters 2 -- 4 (or the resp. keywords). The results
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are written to table given the keyword LINPOS and the
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slitlet positions are taken from table given keyword MOS.
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Then it takes either the grism number from the header of
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WLC (WLCMTD(1) = F) or reads the keywords AVDISP (average
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dispersion) and WCENTER (central wavel.) (WLCMTD(1) = L).
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Using the numbers obtained this way it performs the
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identification of the lines and fits the dispersion
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relation with a polynomial (type keyword POLTYP) of
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degree given by parameter 6. The resulting coefficients
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are stored in the table given by keyword LINFIT and
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- depending on the last parameter - plotted.
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For a detailed description of the fitting procedure see
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on-line help of CALIBRATE/MOS.
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WLDEF/MOS ? ? 10,3 ? -2 3 FC y
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Takes the frame name from keyword WLC and does a line search with
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threshold and width of search window defined by keyword SEAPAR and
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centers the detected lines with the method defined in keyword
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CENTMET. It scans every 10th CCD row and averages 3 rows before
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searching the lines. It takes central wavelength and average
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dispersion/pixel from the keyword belonging to the grism used
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(e.g. FORS01 for grism #1) and does not throw out any bad lines
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during the fit and identification procedure. The tolerance for
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identification is 2 wavelength units and the fit is a 3rd order
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polynomial. The residuals are plotted.