Name

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      DBTARGET

Purpose

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      Find sources in a database within specified radius of specified target

Explanation

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      Uses QuerySimbad to translate target name to RA and Dec, and then uses
      DBCIRCLE() to find any entries within specified radius. Database must
      include items named 'RA' (in hours) and 'DEC' (in degrees) and must
      have previously been opened with DBOPEN

Calling Sequence

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    list = DBTARGET(target, [radius, sublist, /SILENT, DIS= ,/TO_B1950 ] )

Inputs

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      TARGET - A scalar string giving an astronomical target name, which
          will be translated into J2000 celestial coordinates by QuerySimbad

Optional Input

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      RADIUS - Radius of the search field in arc minutes, scalar.
                Default is 5 arc minutes
      SUBLIST - Vector giving entry numbers in currently opened database
              to be searched. Default is to search all entries

Outputs

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    LIST - Vector giving entry numbers in the currently opened catalog
            which have positions within the specified search circle
            LIST is set to -1 if no sources fall within the search circle
            !ERR is set to the number sources found.

Optional Output

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      DIS - The distance in arcminutes of each entry specified by LIST
              to the search center specified by the target.

Optional Keyword Input

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      /SILENT - If this keyword is set, then DBTARGET will not print the
              number of entries found at the terminal
      /TO_B1950 - If this keyword is set, then the SIMBAD J2000 coordinates
              are converted to B1950 before searching the database
              NOTE: The user must determine on his own whether the database
              is in B1950 or J2000 coordinates.
  RESTRICTIONS;
      The database must have items 'RA' (in hours) and 'DEC' (in degrees).
      Alternatively, the database could have items RA_OBJ and DEC_OBJ
      (both in degrees)

Example

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      (1) Use the HST_CATALOG database to find all HST observations within
          5' (the default) of M33
      IDL> dbopen,'hst_catalog'
      IDL> list = dbtarget('M33')
      (2) As above but restrict targets within 2' of the nucleus using the
          WFPC2 camara
      IDL> dbopen,'hst_catalog'
      IDL> sublist = dbfind('config=WFPC2')
      IDL> list = dbtarget('M33',2,sublist)

Procedure Calls

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      QuerySimbad, DBCIRCLE()

Revision History

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      Written W. Landsman SSAI September 2002
      Propagate /SILENT keyword to QuerySimbad W. Landsman Oct 2009
      Make sure a database is open W.L. Oct 2010