%++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ %.COPYRIGHT (c) 1990 European Southern Observatory %.IDENT calibwfors.hlq %.AUTHOR SM, LSW %.KEYWORDS MIDAS, help files, CALIBRATE/MOS %.PURPOSE On-line help file for the command: IDENT/MOS %.VERSION 1.0 09-SEP-1993 : Creation, SM %---------------------------------------------------------------- \se SECTION./MOS \es\co CALIBRATE/MOS 09-SEP-1993 SM \oc\su CALIBRATE/MOS [tol] [degree] [mode] [wcenter],[avdisp] [plotc] display determination of calibration coefficients \us\pu Purpose: Computes wavelength dispersion coefficients \up\sy Syntax: CALIBRATE/MOS [tol] [degree] [mode] [wcenter],[avdisp] [plotc] [disp] \ys\pa tol = tolerance (> 0 in pixels, < 0 in wavelength units) Session keyword: TOL Default: 2 degree = order of fit for dispersion relation Session keyword: WLCORD(1) Default: 2 mode = two-character flag: Session keyword: WLCMTD Default: RC operation mode: I(dent) lines have been identified by IDENTIFY/MOS L(inear) central wavelength and dispersion are given R(ecall) central wavelength and dispersion are given, for one slitlet method linear is applied. Then the first successfull dispersion relation is recalled for the other slitlets. fit mode: C(onstant linelist) - in each slitlet the lines are identified for all rows and a global fit for the whole slitlet is achieved. V(ariable linelist) - for each row the dispersion relation of the first row is used to identify the lines and bad lines are thrown out. T(wo-dimensional fit) - The dispersion relation is fitted in two dimensions - the dispersion and the spatial direction. In dispersion direction polynoms like given in POLYPE are fitted but in spatial direction normal polynoms. wcenter = central wavelength (for mode LINEAR and RECALL) Session keyword: WCENTER Default: 0 avdisp = average dispersion (wavelength/pixel) (only for mode LINEAR and RECALL) Session keyword: AVDISP Default: 0 plotc = plot option for residuals (default: N) Session keyword: PLOTC Default: N disp = display level for results Session keyword: DISP Default: 0 < 50 no display (except positions of bad lines) >= 50 ... < 100 additional display of parameters and first results for each slitlet >= 100 additional display of results for each scanned line \ap\sa See also: SEARCH/MOS, IDENTIFY/MOS \ap\no Note: This command takes the arc lines found by SEARCH/MOS from the table given by the keyword LINPOS (default: linpos) and tries to identify them with the lines listed in the table given by the keyword LINCAT (default: hear). A first guess is obtained either from the lines identified with IDENTIFY/MOS or by the central wavelength and average dispersion, which may be provided by keywords WCENTER, AVDISP, on the command line. With these first estimates a line identification is performed and after this the dispersion relation is fitted again. Lines with residuals larger than the tolerance are thrown out iteratively. The fit procedure is repeated until either the number of identified lines does not change anymore (and the minimum number of iterations has been performed (see WLCNITER(1)) or the maximum number of iterations (see WLCNITER(2)) has been performed. At the end of each slitlet a linear fit to the selected lines is performed to allow an estimation of the mean linear dispersion. This is needed in order to take into account the offsets between the slitlets: these offsets are transformed into wavelength offsets using the mean linear dispersion. Any selection made for table LINPOS will be taken into account, but no selection of table MOS. Taking into account selections of both tables could lead to confusion. If you want the selection flag of table MOS to be effective here, you should redo SEARCH/MOS with the selected MOS table. For any method an appropiate wavelength catalog (LINECAT) is required. Any lines that are not present in the light source should be removed as well as any line blends that occur at the given spectral resolution. The output coeficients are stored in table LINFIT (default: coerbr) \on\exs Examples: \ex CALIBRATE/MOS 2 4 RC 5370,3.0 n 50\\ Uses mode RC (Recall/Constant). The central wavelength (5370 Angstroem) and mean linear dispersion 3.0 Angstroem/Pixel is given in the command line. Tries to identify the lines in the table given by keyword LINPOS (default: linpos) by comparing to the line catalog given by keyword LINCAT (default: hear) with a tolerance of 2 pixels and to fit a polynomial of 4th order to the identified lines. The type of the polnom is taken from keyword POLTYPE. No residuals are plotted plotted. CALIBRATE/MOS -2 3 iv ? y 50 Uses mode IV (Ident/Variable) and takes the pixel positions of identified lines from keyword XPOS and the resp. wavelengths from keyword LID and performs a first fit of 3rd degree. Tries to identify the remaining lines in the table given by keyword LINPOS (default: linpos) by comparing to the line catalog given by keyword LINCAT (default: hear) with a tolerance of 2 wavelength units (e.g. Angstroem) and redo fit. Bad lines are thrown out. The results are given for the first row of each slitlet and plotted. CALIBRATE/MOS -2 3 LT ? n 50 Same as above but a linear dispersion is assumed in any slitlet to identify the lines during the first iteration. The wavelengths are fitted by polynoms in two dimensions - it depends on x and y. The output is stored row by row in table LINFIT (default: coerbr). \xe \sxe