Data Structures

MIDAS tables and keywords are used to store most the information created and/or used by the MOS context. The tables , , , and are created by the MOS commands; the table 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.

.tbl

is created by LOCATE/MOS and used during the whole reduction process. It contains the limits of the slitlets.

.tbl

is created by SEARCH/MOS and updated by CALIBRATE/MOS. It contains the pixel-positions of the calibration lines, the row and the slitlet they belong to, their identifications and their intensities.

.tbl

is created by CALIBRATE/MOS and used by REBIN/MOS. It contains the fit coefficients for the dispersion relations of each row scanned by SEARCH/MOS.

.tbl

is created by DEFINE/MOS and used by FITSKY/MOS and by EXTRACT/MOS. It contains the positions of the objects and the sky regions.

.tbl

contains the wavelength calibration lines. There will be several line-catalogs available in the instrument related system area, adapted for the use with the FORS grisms.

 

Unit Description

SLIT - sequential number of slitlet

YSTART PIXEL first row of slitlet

YEND PIXEL last row of slitlet

XOFFSET PIXEL offset of slitlet

 

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)

 

Unit Description

WAVE ANGSTROEM wavelength of calibration lines

 

Unit Description

SLIT - number of slitlet in which the dispersion relation was determined

ROW PIXEL row in which the dispersion relation was determined

Y - world coordinate of ROW

RMS Angstroem r.m.s. error of dispersion relation (Å)

COEF_i - dispersion coefficients

 

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

   

Unit Description

MAGNITUDE - magnitude

WAVE ANGSTROEM wavelength

BIN ANGSTROEM bin width

FLUX ERG/S/CM/CM/ANG flux

 

Name Default value Contents 3|c|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 counter for slitlets

NSLIT/I/1/1 total number of slitlets

SCAN_POS/D/1/1 0. scan position and width for slitlet location 3|c|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 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 Results of moscalib (+1 dispersion relation fitted, -1 no dispersion relation fitted)

DISP/I/1/1 amount of intermediate display for CALIB/MOS

GRISM/I/1/1 1 No. of grism used

REJTHRES/R/1/1 3. rejection threshold

 

Name Default value Contents 3|c|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 3|c|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 number of objects found by define/mos

NSKY/I/1/1 number of sky-regions found by define/mos

SKYMET/C/1/16 method used to fit sky

SKYPAR/I/1/6 order of fit for polynomial or width of window for median

EXTPAR/C/1/60 extraction parameters (order, iter) 3|c|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 3|c|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

 

Name Default value Contents 3|c|Keywords for CCD parameters

STEP/D/1/2 0.,0. step-size of raw frame

START/D/1/2 0.,0. start values of raw frame

NPIX/I/1/2 0,0 size of raw frame

CCDPAR/C/1/60 read-out-noise and conversion factor of CCD