# AIPS HELP file for COORDINA in 31DEC24

### HELP SECTION

```COORDINA
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

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.
SUFIX.......Modifies source numbers on uv data.  COORDINA provides
the coordinates of a new source.
```

AIPS