AIPS HELP file for COORDINA in 31DEC26

As of Sat Jan 24 10:06:51 2026

HELP SECTION

COORDINA
Type: Adverb   (Real(6))
Use:  An array adverb used to convey coordinate values as:
         Xpos = abs(COOR(1)) + abs(COOR(2))/60 + abs(COOR(3))/3600
            if any of COOR(1), COOR(2), COOR(3) < 0: Xpos = -Xpos
         Ypos = abs(COOR(4)) + abs(COOR(5))/60 + abs(COOR(6))/3600
            if any of COOR(4), COOR(5), COOR(6) < 0: Ypos = -Ypos
      Note that, although these are most suited to RA, Dec in
      sexagesimal notation, they can be used for any type of coordinate.
      The units are standard units of the X and Y axes (e.g degrees,
      m/sec, Hz, sec, etc.) except that right ascensions are in hours of
      time.

      It is normal in print to represent a declination between -1 and
      0 degrees as -0d mm ss.s.  But if you type, e.g.
          COORDINA = 14, 8, 23.3, -0, 14, 23
      you will get a positive declination because there is no
      difference numerically between -0 and +0.  You need to type
          COORDINA = 14, 8, 23.3, -0, -14, 23
      to get the desired negative coordinate.  BE VERY CAREFUL when
      you type negative coordinates to use commas to separate the
      values.  Otherwise the minus sign becomes a subtraction sign and
      you do not get the desired values in the adverb.

Null value:  None, 0 means 0.

Verbs:
   CODECIML......Convert between decimal and sexagesimal coordinate
                 values
   COODEFIN......Define or modify an image axis coordinate description
   COPIXEL.......Convert between physical and pixel coordinate values
   COSTAR........Plot a symbol on the TV at the specified coordinate.
   COTVLOD.......Load a TV image centered on the specified coordinate.
   COWINDOW......Set BLC, TRC centered on a coordinate.
   EPOCONV.......Convert between J2000 and B1950 coordinates
   IMCENTER......Returns pixel position of sub-image centroid
   IMPOS.........Displays celestial coordinates selected by the TV
                 cursor
   IMVAL.........Returns image intensity and coordinate at specified
                 pixel
   MAXFIT........Returns pixel position and image intensity at a maximum
   QIMVAL........Returns image intensity and coordinate at specified
                 pixel quietly

Build-in procedures:
   TVFLUX........Displays coordinates and values selected with the TV
                 cursor
   TVMAXFIT......Displays fit pixel positions and intensity at maxima on
                 TV

Tasks:
   CHKFC.........Makes images of Clean boxes from Boxfile.  COORDINA
                 sets the center coordinate when the BOXFILE contains
                 boxes defined as shifts.
   FLATN.........Re-grid multiple fields into one image incl sensitivity
                 COORDINA selects the output central coordinate.
   MODAB.........Makes simple absorption/emission spectral-line image in
                 I/V.  COORDINA defines the central RA/Dec coordinate.
   MODIM.........Adds images of model objects to image cubes in IQU
                 polarization.  COORDINA defines the central RA/Dec when
                 making a brand new image.
   MODSP.........Adds images of model objects to image cubes in I/V
                 polarization.   COORDINA defines the central RA/Dec
                 when making a brand new image.
   PBCOR.........Task to apply or correct an image for a primary beam.
                 COORDINA provides the pointing center if necessary
   SDVEL.........Shifts spectral-line single-dish data to a given
                 velocity.  COORDINA provides the coordinate to be used
                 for the velocity reference.
   SPCOR.........Task to correct an image for a primary beam and
                 spectral index.  COORDINA provides the pointing center
                 if necessary.
   SPXMD.........Adds images of model objects to image cubes in spectral
                 index.
   SUFIX.........Modifies source numbers on uv data.  COORDINA provides
                 the coordinates of a new source.
   TX2IM.........Converts a 1-dimensional text file into cataloged image

EXPLAIN SECTION