
1 ASTROMETRIC
        ASTROMETRIC [RAmin RAmax DECmin DECmax]  [/MAGNITUDE  Mlim]  [/EPOCH
    date] [/OUTPUT File]

    Search and plots all astrometric  stars  of  magnitude  less  than  Mlim
    (brighter than Mlim) in the (RA,DEC) box specified by RAmin RAmax DECmin
    DECmax (if present, and in the current Greg box otherwise, provided that
    the  coordinate  system  is equatorial). The current marker type is used
    and the size depends  on  the  current  marker  size  and  on  the  star
    magnitude.   The proper motions are included to represent the sky at the
    date specified in the /EPOCH option  if  present,  at  the  current  day
    otherwise.  The  stars  are  precessed to current equinox, as defined in
    variable  GEPOCH.  If  option  /OUTPUT  is  present,   star   positions,
    magnitudes,  spectral  types and names are written in the specified file
    (which defaults to user terminal).

    NOTES:
      - Palomar/SRC Survey Schmidt Plates (POSS#I) are squares of size 35.56
        cm (14 inches) with a scale of 67.14 Arcsec. per mm.
      - ESO Survey Plates are squares of size 30 cm with  a  scale  of  67.6
        Arcsec. per mm.
    If you want to make overlays, do not forget the /EXACT option in command
    HARDCOPY/PLOT ...
1 FLASH
        [ALL\]FLASH [Filename] [/PLANE I1 I2] [/SUBSET Imin Imax Jmin Jmax]

    Displays the GILDAS byte image Filename. The image values must be in the
    range  0-241  (unsigned  bytes) to be immediately displayed on the image
    processor. This command is intended for quick look to an  image.  Hence,
    no  scaling  occurs,  and the byte image is not transmitted to GreG, but
    will take the place of the image in a PostScript output  if  no  command
    "PLOT"  is  given  before  asking  for the OVERLAY command. However, the
    current Regular-Grid array stills points to the last  image  defined  by
    command  IMAGE,  and can be displayed without computations using command
    PLOT.

    The /PLANE I1 I2 option  allows  to  define  part  of  a  more  than  2-
    Dimensional  image  as  the  current  image.  A  file name should not be
    specified if you want to select a new plane in the current image.

    The /SUBSET Imin Imax Jmin Jmax option allows to load only a  subset  of
    the  input  image or image plane. Again, a file name should be specified
    only to change the input image.

    You can combine /PLANE and /SUBSET options.
1 RGB
        [ALL\]RGB [RedFilename GreenFilename BlueFilename] [RGB or SHARP  or
    PHOTO] [/PLANE I1 I2] [/SUBSET Imin Imax Jmin Jmax]

    Displays  three  GILDAS  byte  images  RedFilename,  GreenFilename   and
    BlueFilename,  in  this  order, as a "truecolor" image (see HELP SAVE to
    know how to make such byte images). The  user  has  the  choice  between
    three  flavours  for displaying on 8-bits what is essentially an 24-bits
    problem: using either the default (PHOTO) value,  that  will  give  more
    photographic  washed-out  colors,  the "SHARP" option, same as PHOTO but
    without unsaturated colors, or  the  simple-minded  "RGB"  option,  that
    divides  the  R,G,B  cube in (cubic root of the number available colors)
    parts on each axis. Test it to feel the differences.  The  corresponding
    LUT is loaded along with the command, see also HELP LUT.  The byte image
    is not transmitted to GreG, but will take the place of the  image  in  a
    PostScript  output  if  no command "PLOT" is given before asking for the
    hardcopy  (ALL\OVERLAY command). The current Regular-Grid  array  stills
    points to the last image defined by command IMAGE, and will be displayed
    without computations using command PLOT.

    The /PLANE I1 I2 option allows to define part of more than 2-Dimensional
    images as the R,G,B image.

    The /SUBSET Imin Imax Jmin Jmax option allows to load only a  subset  of
    the input images or image planes.

    You can combine /PLANE and /SUBSET options.

1 HEADER
        HEADER [Image_Name] /EXTREMA

    Compute the extrema of the current or specified image,  and  update  the
    header accordingly.
        HEADER /UPDATE

    Update the header of the current image, for example after  modifications
    to the G_* header variables have been made. The header variables are
    G_NDIM         Number of dimensions
    G_DIM[4]       Image dimensions
    G_CONVRT[3,4]  Conversion formula (Ref, Val, Inc for each axis)
    G_BLANK[2]     Blanking and tolerance
    G_MAX          Maximum value
    G_MIN          Minimum value
    G_EXTREMA      Zero (0) if no extrema defined
    G_WHERE[2,4]   Pixel of maximum and minimum
    G_UNITi        Units of axis i
    G_UNIT         Units of map
    G_COORD        System coordinates
    G_SOURCE       Source name
    G_EPOCH        Epoch of coordinates
    G_RA           Right Ascension (of Object)
    G_DEC          Declination (of Object)
    G_LII          Galactic longitude (of Object)
    G_BII          Galactic latitude (of Object)
    G_PTYP          Projection Type (0:none,1:Gnomonic,2:Orthographic,
                    3:Azimuthal,4:Stereographic,5:Lambert,6:Aitoff,7:Radio).
                    Warning: these codes are subject to change without notice.
    G_XAXI         The first axis of projection (1,2,3 or 4)
    G_YAXI         The second axis of projection (1,2,3 or 4)
    G_A0           Position of projection center for axis G_XAXI (R.A. or LII)
    G_D0           Position of projection center for axis G_YAXI (DEC. or BII)
    G_ANGLE        Angle of projection (East of North)
    G_LINE         Line name
    G_FREQRES      Frequency resolution
    G_RESTFRE      Signal rest frequency
    G_FREQOFF      Image rest frequency
    G_VELRES       Velocity resolution
    G_VELOFF       Velocity of reference channel
    G_PA           Position angle of beam
    G_MINOR        Minor axis size of beam
    G_MAJOR        Major axis size of beam
    G_BEAM         Size of RESOLUTION section (0 or 3)

        HEADER [Image_Name] [/OUTPUT FIle_Name]

    Give the Header of the current or specified Image, on the screen  or  in
    the  specified output file.  Provided you have write access to the image
    and nobody else is already using it, the header may be edited on DEC/VMS
    machines  if  the  terminal is a VT100 compatible. The keys of the VT100
    keypad have the same meaning as in DEC's EDT:
               +--------+--------+--------+--------+
               |  enter |        |        |  Del L |
               |  edit  |        |        |        |
               +--------+--------+--------+--------+
               |  print |        |        |  Del W |
               |  header|        |        |        |
               +--------+--------+--------+--------+
               | Advance| Backup |        |  Del C |
               |        |        |        |        |
               +--------+--------+--------+--------+
               |  Word  |   Eol  |  Char  |        |
               |        |        |        |  Enter |
               +--------+--------+--------+        |
               |       Line      |        |(Update)|
               |                 |        |        |
               +-----------------+--------+--------+
     To edit a field, press the GOLD (PF1) key.
     To compute MAXIMA and MINIMA of current image, strike ENTER key.
     Strike <^Z> to exit.
     The header will be automatically updated if any modification  has  been
    made.
1 IMAGE
        [ALL\]IMAGE [Filename] [/PLANE I1 I2] [/SUBSET Imin Imax Jmin Jmax]

    Read the GDF map Filename. The default  image  extension  is  .GDF  This
    command  defines  the image found in given file as the new current image
    to be used by next PLOT command. The  image  also  becomes  the  current
    Regular Grid array in GreG. The box location is reset by this command to
    match the image boundary.

    The /PLANE I1 I2 option  allows  to  define  part  of  a  more  than  2-
    Dimensional  image  as  the  current  image.  A  file name should not be
    specified if you want to select a new plane in the current image.

    The /SUBSET Imin Imax Jmin Jmax option allows to load only a  subset  of
    the  input  image or image plane. Again, a file name should be specified
    only to change the input image.

    You can combine /PLANE  and  /SUBSET  options.  The  behaviour  of  this
    command  depends  on  the  current  MODE defined by command SET MODE. In
    IMAGE MODE, a single plane is mapped. In CUBE MODE, the whole  image  is
    mapped.  CUBE  MODE is still not quite coherent with GreG languages, and
    should be used only for MOVIES.

1 IRAS
        [ALL\]IRAS Band [Ramin Ramax Decmin Decmax] [/FLUX Threshold] [/SIZE
    Flux_value]

    Plots a marker at the position of all IRAS  point  sources  detected  at
    band  Band (specified by its wavelength in microns 12, 25, 60 or 100) in
    the area  defined  by  Ramin,  Ramax  (in  hours),  Decmin,  Decmax  (in
    degrees). If the option /FLUX is given, only sources with a flux greater
    than Threshold will be selected. If  the  option  /SIZE  is  given,  the
    marker  size  will be proportional to the logarithm of the flux (sources
    with a flux equal to  Flux_value  having  the  current  marker  size  as
    specified by SET MARKER command). The current marker type is used.

    Command IRAS completely ignores the current GreG box to select the  IRAS
    point sources, but the markers will be clipped in this box when plotted.
    Hence, it is up to the user to ensure that the system is EQUATORIAL  and
    that  the  projection  area (specified by command LIMITS and PROJECTION)
    reasonably matches the selection area specified in command IRAS.
1 KILL
        [ALL\]KILL

    KILL calls the interactive cursor.  Recognised keys are:
      - V to give the value of the pixel
      - K to give the current blanking value to the pixel
      - I to interpolate the value from the neighbour pixels.
      - E to exit from interactive cursor mode
    Any other key is ignored.


1 Language
                        ALL\ Language Summary

    ASTROMETRIC     : Plots astrometric star positions (for finding charts)
    FLASH File      : Displays a byte image.
    HEADER [Name]   : Give the Header of the current or specified Image.
    IMAGE [Name]    : Read the image Name. Default extension is .GDF
    IRAS Band       : Select and plot IRAS sources of a given band
    KILL [i j]      : Kills pixels
    LIST            : Show current operating modes
    LOOK            : Use the image cursor to look for image values
    LUT [arg]       : Change the color Look-Up-Table
    MOVIE           : Make a movie for a cube
    PAN [i j]       : Move the zooming window around a new pixel
    OVERLAY File    : Make a PostScript hardcopy of image and graphics
    PLOT            : Plot the image and redraw graphics
    PSC_IRAS        : Get characteristics of IRAS point source
    REGRESSION [Val]: Computes regression lines
    RGB r g b [mode]: Plots 'truecolor' mix of 3 byte images
    SAVE File       : Saves bitmap in image format.
    SET Mode        : Select some operating mode
    SPECTRUM        : Extract a spectrum from an image (to plot it).
    ZOOM            : Zoom part of the image.

1 LIST
        [ALL\]SHOW

    Lists some internal parameters of the OVERLAY program  :  scaling  mode,
    range, etc...


1 LOOK
        [ALL\]LOOK

    Examine pixel values using the mouse pointer. Click central  button  for
    examining values, left button to exit.

1 LUT
        [ALL\]LUT Argum

    Modify the color look up table. Possibles arguments  are
      - COLOR Load a default color table
      - WHITE Load a black and white color table  (White  background,  black
        sources)
      - BLACK Load a black and white color table  (Black  background,  white
        sources).
      - RGB , PHOTO and SHARP load three different  LUTs  used  by  the  RGB
        command.
      - LUT Load the color table defined by the Hue array  HUE.   Saturation
        and Value (Brightness) of the HSV model are defined by the variables
        SATURATION and VALUE respectively. The HUE  array  can  be  obtained
        from the original LUT array using standard SIC mathematic functions.
        The number of actual colors used by OVERLAY on  the  display  (i.e.,
        the size of the arrays) is given by the SIC variable LUT_SIZE.
      - Any other : Red Green Blue values are read from the  formatted  file
        named "Argum".

    The default argument is LUT. A convenient value for the HUE array is
      LET HUE[I] = 256-I
        a "classical" color table from blue to  red  as  used  in  AIPS  for
        example.  Color contours can be obtained using variations around the
        following command
      LET HUE[I] = 16*INT((LUT_SIZE-I)|16)
        and so on with the most funny functions you may invent.


    CAUTION : the HUE is a real number between 0 and 360.0


1 MOVIE
        ALL\MOVIE

    Start a movie procedure. The button control the movie mode
      - Left button : Stop movie command
      - Middle button : Image by image mode
      - Right button : Start movie
    Movie speed is controlled by pointer position (left fast,  right  slow).
    MOVIE mode must have been selected when mapping the image.

1 OVERLAY
        ALL\OVERLAY File [Format]

    Creates a copy of  the  current  image  and  overlayed  graphic  in  the
    specified  format  (only  PostScript  is  available  now,  others are in
    development).  Default file extension is .PS for PostScript files.   The
    PostScript files may be sent to the LaserPrinter.

1 PAN
        [ALL]\PAN [Cx Cy]

    Move the zooming area to center it  around  the  pixel  (Cx,Cy)  of  the
    current  image.  The  zooming  factor  is not changed. If no argument is
    given, use the mouse to point towards the center.

1 PLOT
        [ALL]\PLOT /GREG "Valid_GreG_Action" /PLANES List_of_Planes

    Computes the bitmap from the current image  and  plot  it  in  the  GreG
    window.   The range specified by SET RANGE, and the scaling specified by
    SET SCALE  are used. If neither the image, nor  the  scaling  parameters
    have changed, the last bitmap is replotted without computations.

    The two options /GREG and /PLANES are restricted to the CUBE mode, where
    several planes of a data cube are plotted at the same time.  They enable
    you to make a valid GreG action (BOX, RGM, GRID, etc...) for all  planes
    (default)  or  a  list  of  planes  specified in the /PLANES option. The
    "Valid_GreG_Action" should be put between double quotes if  the  command
    is  longer  than one word. The List of Planes is the number(s) of planes
    for which the action should be undertaken, the syntax is the same as  in
    the GREG2\LEVELS command:
        i1 i2 i3 to i4 by i5 i6 i7 i8 to i9 i10 ....
        Example:
        SET MODE CUBE
        IMAGE TOTO /PLANE 8 11
        PLOT/GREG "BOX n n n"
        ! Will draw an unlabeled box around each plotted plane
        PLOT/GREG "AXIS XL/UNIT S"/PLANES 10 11
        ! Will draw a labeled axis for the two lower boxes
    All graphics commands are replayed.

1 PSC_IRAS
        [ALL\]PSC_IRAS [Ra.#Dec.] [/OUTPUT Filename] [/LOOK Around]

    Find  IRAS  characteristics  of  point  sources  around  the   specified
    position.  If no position is given, it calls the interactive cursor, and
    uses the returned coordinates to look for all IRAS sources  around  this
    point.  The  value  Around (argument of option /LOOK) is the size of the
    search area in arc minutes (default 1). The result depends  whether  the
    full compact catalog is on line or not.
      - If not, the fluxes of the sources found in the search box are  typed
        on the screen.
      - If it is on line, full information about the sources is either typed
        on  the  screen,  or  written  on the file specified by the argument
        Filename of option /OUTPUT.
    In addition,  a  binary  output  file  (whose  name  is  PSCSUB.TAB)  is
    produced.   This binary file is suited for later processing by the Point
    Source Catalog software. The same files (formatted and binary) are  used
    for  multiple  use  of  this command (unless the Filename is explicitely
    changed).

2 Format

    The listing produced by PSC_IRAS or the IRAS command has  the  following
    format :

    Right Ascension         Sexagesimal notation in Hours
    Declination             Sexagesimal notation in Degrees
    Lii                     (Degrees)
    Bii                     (Degrees)
    Semi-Major axis of position uncertainty ellipsis  (  Arc Seconds
    Semi-Minor axis of position uncertainty ellipsis   95 confidence)
    Position Angle of the uncertainty ellipsis. (Degrees from North)
    Number of Hour confirmations
    Number of LRS spectra
    Type of LRS spectra
    Variability flag
    Discrepant flux flag
    Confusion flux flag
    Number of nearby hour confirmed point sources
    Number of nearby week confirmed point sources
    High source density bin flag
    CIRR1   Cirrus flag 1
    CIRR2   Cirrus flag 2
    CIRR3   100 micron sky brightness (MJy/Sr)
    Number of identifications
    Type of identifications

    For each flux (12, 25, 60 100 microns)
            Flux    (Jy)
            Flux quality (1 upper limit, 2 poor, 3 good)
            Calibration uncertainty (%)
            Signal to noise ratio multiplied by 10
            Point source correlation coefficient
            Number of hour confirmed small extended sources
            Number of week confirmed small extended sources

    Identifications (one line per identification)
            Name
            Catalog dependant informations
            Catalog name

1 REGRESSION
        REGRESSION Nmin [/RANGE [X Xmin Xmax] [Y Ymin Ymax]]

    Computes linear regressions in a image which is the correlation  of  two
    coincident images. The regression lines
           Y = A * X + B   and    X = A'* Y + B'
    are computed assuming the weight of any (X,Y) is the value of the  pixel
    at  X,Y. Nmin is the minimum pixel value considered as significant.

1 SPECTRUM
        SPECTRUM I [J [K]]

    Extract a spectrum from an image according to the following numbering :
        Spectrum (l) = Image (l,i,j,k)
    for a 4-dimensional image. The spectrum is loaded into the  X,Y  buffers
    of  GreG.  It  can  be  processed later by the standard commands LIMITS,
    CONNECT, CURVE and so on.
1 SAVE
        [ALL\]SAVE File

    Saves the current displayed bitmap in a GILDAS  image  in  Byte  format.
    The resulting image can be redisplayed quickly using command FLASH.
1 SET
        [ALL\]SET Item Value

    Specify some OVERLAY parameters. Available parameters are :
      - SET RANGE AUTO or SET RANGE LOW_CUT HIGH_CUT
        specify the range of values to be displayed in the bitmap.
      - SET SCALING  LINEAR  or  SET  SCALING  LOGARITHMIC  or  SET  SCALING
        EQUALIZATION.
        specify the transformation  applied  to  the  image  to  obtain  the
        bitmap.  LINEAR is the fastest, EQUALIZATION the slowest.  Moreover,
        EQUALIZATION scaling requires a  large enough  map  with  sufficient
        dynamic  range. The EQUALISATION scaling tries to find the levels in
        the map that will give more or less the same number  of  pixels  for
        each color value. The levels thus found are kept in the SIC#VARIABLE
        "LEVELS", and can be used to assign levels values to GreG  (for  the
        RGMAP command).
      - SET LEVELS nlev
        modifies the number of different values, i.e., colors  (default:241)
        in  which  the  image is scaled if SET SCALING EQUALIZATION has been
        chosen. useful for hardcopies on some plotters  with  few  different
        grey  or  color levels, and if the image has less than 241 different
        values.  SET SCALING LIN or LOG restores nlev to 241 (the LUT size);
        The number of levels used is accessible through the SIC#VARIABLE NLS
      - SET MODE CUBE or SET MODE IMAGE
        Specify in which mode you want  to  display  the  input  data  cube.
        IMAGE mode is used to display the cube plane by plane, in CUBE mode,
        OVERLAY tries to show as much planes as possible on the same  image.
        See  Command  PLOT  for  details.  CUBE  mode  is  also used to make
        "movies".
      - SET X (or Y) INCREASING or DECREASING
         Specify whether image  should  be  displayed  using  increasing  or
        decreasing user coordinates along X or Y axis.
1 ZOOM
        [ALL\]ZOOM [X_blc Y_blc X_trc Y_trc]

    Display the area specified by its  bottom  left  corner  and  top  right
    corner  in  the  ZOOM  window.  If  no  area is specified, use the mouse
    pointer to define the  corners.  The  command  is  chained  with  a  PAN
    command.





















