Data Structures

MIDAS tables and keywords are used to store most the information created and/or used by the MOS context. The tables $\fbox{{\small \tt MOS}}$ , $\fbox{{\small \tt LINPOS}}$ , $\fbox{{\small \tt LINFIT}}$ , and $\fbox{{\small \tt WINDOWS}}$ are created by the MOS commands; the table $\fbox{{\small \tt LINECAT}}$ is available in the MIDAS data base. A short description of the tables is given below; a detailed description of their contents can be found in Table L.6.

Table LINPOS
Label	Unit	Description
`X`	`PIXEL`	x-position of calibration line
`Y`	-	world coordinate of row in which the line was found
`PEAK`	-	Peak intensity of calibration line
`SLIT`	-	number of slitlet in which the line was found
`WAVE`	`Angstroem`	identification of the line (Å)
`WAVEC`	`Angstroem`	fitted wavelength (Å)
`RESIDUAL`	`Angstroem`	`WAVEC-IDENT` (Å)
`REJECT`	-	Rejection code (-5: line has been rejected due to too large residual)

Table WINDOWS
Label	Unit	Description
`OBJ_SLIT`	-	number of slitlet in which the object was found
`OBJ_STRT`	-	first row of the object's spectrum (world coordinates)
`OBJ_END`	-	last row of the object's spectrum (world coordinates)
`NET_INTENS`	-	net peak intensity the object's spectrum
`SKY_STRT`	-	first row of sky regions (world coordinates)
`SKY_END`	-	last row of sky regions (world coordinates)
`SKY_SLIT`	-	number of slitlet in which the sky was found

Name	Default value	Contents
Keywords for flat-field related commands
FLATLIM/R/1/3	0,0,0	detection parameters for slitlet location (detection threshold, median width, lower limit)
FFORD/I/1/1	3	order of fit for the FF normalization
NORMMET/C/1/20	POLY	method for FF normalization
ISLIT/I/1/1	0	counter for slitlets
NSLIT/I/1/1	0	total number of slitlets
SCAN_POS/D/1/1	0.	scan position and width for slitlet location
Keywords for wavelength calibration related commands
SEAPAR/C/1/20	200,5	detection threshold and width
YBIN/C/1/20	3,3	Step and Binning in Y
CENTMET/C/1/16	GRAVITY	centering method for calibration lines
XPOS/D/1/50	0.	Positions of identified lines (pixels)
LID/D/1/50	0.	Positions of identified lines (Angstroems)
WLCMET/C/1/2	FC	Wavelength calibration method (Ident/Linear/ Fors) and (Constant/Variable/Fit)
POLTYP/C/1/10	CHEBYSHEV	type of polynomials used for fitting (Polynom, Legendre or Chebyshev)
TOL/R/1/1	2.0	tolerance for autom. wavel. ident. (< 0 Å, > pix)
TOLWIND/I/1/1	4	tolerance window for interact. wavel. ident.
WLCORD/I/1/2	2,1	order of fit used to compute the dispersion
ALPHA/R/1/1	0.2	Rejection parameter for lines matching [0,.5]
SHIFTTOL/I/1/1	10	tolerance for line identification from one slitlet to next
YSTART/I/1/1	0	Starting row for calibration (pixel value)
WLCNITER/I/1/2	3,20	Minimum, Maximum number of iterations
MAXDEV/R/1/1	10.	Maximum deviation (pixels)
WCENTER/D/1/1	0.	Central wavelength
AVDISP/R/1/1	0.	Average dispersion per pixel
PLOTC/C/1/1	N	Plot residuals of wavelength calibration
CAL/I/1/100	0	Results of moscalib (+1 dispersion relation fitted, -1 no dispersion relation fitted)
DISP/I/1/1	0	amount of intermediate display for `CALIB/MOS`
GRISM/I/1/1	1	No. of grism used
REJTHRES/R/1/1	3.	rejection threshold

Table L.9: Keywords used in context MOS (cont'd)

Name	Default value	Contents
Keywords for rebinning commands
REBMET/C/1/12	LINEAR	Rebinning method (LINEAR, QUADRATIC, SPLINE)
REBSTRT/D/1/1	0.	Starting wavelength for rebinning
REBEND/D/1/1	0.	Final wavelength for rebinning
REBSTP/D/1/1	0.	Wavelength step for rebinning
Keywords for object extraction and sky subtraction related commands
THRESH/R/1/1	-0.04	detection threshold for object search
WIND/I/1/1	5	detection window for object search
XBIN/I/1/1	20	Binning in X for object search
SCAN_POS/D/1/1	0.	center for scan (define/mos) in world coordinates
INT_LIM/D/1/1	0.001	fraction of central intensity where object limits shall be defined
NOBJ/I/1/1	0	number of objects found by define/mos
NSKY/I/1/1	0	number of sky-regions found by define/mos
SKYMET/C/1/16		method used to fit sky
SKYPAR/I/1/6	0	order of fit for polynomial or width of window for median
EXTPAR/C/1/60		extraction parameters (order, iter)
Keywords for frame names
OBJ/C/1/60		object frame
EXTOBJEC/C/1/60		extracted object frame
CALOBJEC/C/1/40		extracted object frame
SKYFRAME/C/1/60	sky	sky frame
WLC/C/1/60	wlc	calibration frame
FLAT/C/1/60	flat	flat-field
NORMFLAT/C/1/60	normflat	normalized flat-field
Keywords for table names
MOS/C/1/60	mos	table with slitlets' positions
LINFIT/C/1/60	coerbr	table with dispersion coefficients
LINPOS/C/1/60	linpos	table with wavelength positions
LINECAT/C/1/60	hear	table with wavelength positions
WINDOWS/C/1/60	windows	table with sky and objects positions