AIPS NRAO AIPS HELP file for IMCENTER in 31DEC18



As of Mon Jan 22 15:15:46 2018


IMCENTER: Verb to find coordinates of sub-image centroid

INPUTS

INNAME                             Image name (name)
INCLASS                            Image name (class)
INSEQ           0.0      9999.0    Image name (seq. #)
INDISK          0.0         9.0    Disk drive #
BLC            -1.0                Bottom left pixel
TRC             0.0                Top right pixel
FLUX                               Include pixels > FLUX
PRTLEV         -2.0        10.0    <= -1 => no display results
         @      Output adverbs
PIXXY    @                         Fitted (X,Y,...) pixel of
         @                         maximum.
COORDINA @                         Coordinates at pixel
ERROR    @                         > 0 => fit failed, else okay

HELP SECTION

IMCENTER
Type: Verb
Use:  IMCENTER reads a piece of an image and finds the
      intensity-weighted centroid.
Adverbs: (inputs)
  INNAME......Image name(name).       Standard defaults.
  INCLASS.....Image name(class).      Standard defaults.
  INSEQ.......Image name(seq. #).     0 => highest.
  INDISK......Disk drive # of image.  0 => any.
  BLC.........Bottom left corner.  If BLC = -1,r then do a circle of
              radius r pixels centered on the TRC position
  TRC.........Top right corner or center of circle in pixels
  FLUX........If FLUX > 0, ignore all image values below FLUX.  If
              FLUX < 0, ignore all image values less than -FLUX in
              absolute value.  WARNING: if FLUX is set too low, the
              centroid can be pulled away from the obvious position by
              more than one might first expect.
  PRTLEV......Print level: if <= -1, then do not put result info
              in message file, otherwise do a coordinate display
Adverbs: (outputs)
  PIXXY.......Fitted (X,Y,...) position of centroid
  COORDINA....The X and Y coordinates are found as:
              Xpos = abs(CO(1)) + abs(CO(2))/60 + abs(CO(3))/3600
                 if any of CO(1), CO(2), CO(3) < 0: Xpos = -Xpos
              Ypos = abs(CO(4)) + abs(CO(5))/60 + abs(CO(6))/3600
                 if any of CO(4), CO(5), CO(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 FITS units (e.g
              degrees, m/sec, Hz, sec, etc.) except that right
              ascensions are in hours of time.
  ERROR.......If the verb is not aborted for error, but the fit
              fails (all pixels < FLUX), ERROR will be TRUE (1), else
              it will be FALSE (-1).  Used to detect failures without
              stopping a procedure or RUN file.

EXPLAIN SECTION


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