Table Formats

MIDAS table files are used to store relevant information in tabular form. Four types of tables are considered. The first two, tables order.tbl and line.tbl, are operational tables generated by the user during the session. The other two types of tables are provided by the system to calibrate the data in wavelength and flux.

order.tbl -- Contains echelle orders. This table contains the coefficients a_ij in relation 7.2 stored as descriptors. The table is created by the command DEFINE/ECHELLE or DEFINE/HOUGH

back.tbl -- Contains information related to the background reference positions. This table is created by the command PREPARE/BACKGROUND which is called by DEFINE/ECHELLE and DEFINE/HOUGH.

line.tbl -- Contains information related to the position of the calibration lines. This table contains the dispersion coefficients for each spectral order, stored as descriptors after the line identification process. It is generated by the command SEARCH/ECHELLE and extended and updated by the command IDENTIFY/ECHELLE.

Line Catalogue

-- Contains the wavelength calibration lines. There are several line catalogues available in instrument related system area, like MID_CASPEC and MID_EFOSC.

Standard Stars

-- Contains the fluxes of standard stars in different units. These tables are copied automatically from the area MID_STANDARD into the user work space with the command SET/ECHELLE FLUXTAB=name

 

Table 7.1: Auxiliary Tables

Table order.tbl
Label	Unit	Description
ORDER	-	sequential order number
X	PIXEL	sample (x-axis) position of the order
Y	PIXEL	line (y-axis) position of the order
YFIT	PIXEL	fitted line (y-axis) position of the order
RESIDUAL	PIXEL	residual ( Y-YFIT)
Table back.tbl
Label	Unit	Description
ORDER	-	sequential order number
X	PIXEL	sample (x-axis) position of the order
YBKG	PIXEL	line position of the background above the order
BKG	DN	value of the background
Table line.tbl
Label	Unit	Description
X	PIXEL	sample (x-axis) position of the line
Y	PIXEL	relative order number
PEAK	DN	estimated line maximum
YNEW	PIXEL	line (y-axis) position of the line
ORDER	-	spectral order number
IDENT	ANGSTROM	manual identification
WAVEC	ANGSTROM	computed wavelength
RESIDUAL	ANGSTROM	residual (WAVEC-WAVE)
Line Catalogue
Label	Unit	Description
WAVE	ANGSTROM	wavelength
Standard Star Atlas
Label	Unit	Description
MAGNITUDE	-	magnitude
WAVE	ANGSTROM	wavelength
BIN_W	ANGSTROM	bin width
FLUX_W	ERGS/S/CM/CM/ANG	flux