ARCGENDB-Convert list of laboratory values to feature data base.

Usage:

arcgendb in fdb

Description:

This routine converts an arc line list - i.e. an ASCII list of laboratory wavelengths or frequencies of known features in an arc spectrum - into a feature data base. That can be used for automatic identification of features in an observed arc spectrum.

Parameters:

INFO

INFO = _LOGICAL (Read) If true, informational messages will be issued.

IN

IN = FILENAME (Read) The name of the input ASCII list of wavelengths or frequencies. The list must be strictly monotonically increasing.

FDB

FDB = NDF (Read) The name of the output file to hold the feature data base. This is formally an NDF.

Examples:

arcgendb $FIGARO_PROG_S/thar.arc thar_arc
   This will convert the Th-Ar list from the Figaro release into a
   "feature data base" by the name of "thar_arc.sdf".

References:

Mills, D., 1992, Automatic ARC wavelength calibration, in P.J. Grosbol, R.C.E. de Ruijsscher (eds), 4th ESO/ST-ECF Data Analysis Workshop, Garching, 13 - 14 May 1992, ESO Conference and Workshop Proceedings No. 41, Garching bei Muenchen, 1992

Source comments:

   A R C G E N D B

   Since generating the feature data base may take some time, you may
   want to do it once for any line lists you often use, and keep the
   feature data bases. On the other hand, the feature data bases may
   be rather big.

   This routine reads a list of laboratory values (wavelengths or
   frequencies). The list must be an unformatted ASCII file. From the
   beginning of each line one value is read. If this fails, the line
   is ignored. Comment lines can be inserted by prefixing them with
   "*", "!" or "#". The value can be followed by any comment, but can
   be preceded only by blanks. The list must be strictly
   monotonically increasing.

   The list should to some degree match an expected observation. Its
   spectral extent should be wider than that of an expected
   observation. But it should not contain a significant number of
   features that are usually not detected. This is because the
   automatic identification algorithm uses relative distances between
   neighbouring features. If most neighbours in the list of
   laboratory values are not detected in the actual arc observation,
   then the algorithm may fail to find a solution or may return the
   wrong solution.

   The given list is converted to a feature data base according to
   Mills (1992). The data base contains information about the
   distances between neighbours of features. The scope of the feature
   data base is the number of neighbours about which information is
   stored. The feature data base is stored in an extension to a dummy
   NDF. The NDF itself has only the obligatory data array. The data
   array is one-dimensional with 1 pixel. All the actual information
   is in an extension with the name "ECHELLE" and of type
   "ECH_FTRDB". Its HDS components are:

   -  FTR_WAVE(NLINES)           <_REAL>
   -  FTR_DB(10,10,NLINES)       <_REAL>
   -  FTR_LEFT(10,10,NLINES)     <_BYTE>
   -  FTR_RIGHT(10,10,NLINES)    <_BYTE>
   -  WAVE_INDEX(10,10,NLINES)   <_UWORD>
   -  QUICK_INDEX(5000)          <_INTEGER>
   -  QENTRIES(5000)             <_REAL>

   NLINES is the number of features listed in the input file. The
   scope (=10) controls about how many neighbours information is
   stored in the data base. The index size is fixed to 5000, which
   seems sufficient for NLINES = 3500. The size of the FDB is

      (804 * NLINES + 40000) bytes

   plus a small overhead for the HDS structure and the nominal NDF.
   So it is 10 to 100 times bigger than the original ASCII list. The
   point about the FDB is the reduced computing time when
   auto-identifying features in an observed arc spectrum.