DB_CHART

COMMAND TYPE : GRAPHIC

PURPOSE:

By means of this command you can display on a graphic terminal a selected sky area with objects from one or more catalogues.

DESCRIPTION:

This command draws a map of the objects selected from one or more catalogues (max 8) inside an area defined by means of sky coordinates. The user can work on equatorial, galactic and supergalactic coordinates, if these coordinates are present in the catalogues fields. When the user works with galactic or supergalactic coordinates he must set the name of the coordinate with the CVAriable and type with COOrdinate commands. or he can have unpredictable results. Starting from equatorial coordinates the user can create a 'not interactive' galactic or supergalactic map.

Many catalogues can be superimposed on a map and displayed with different colors and symbols on the screen. In the display you can use different projection as: Mercator,Lambert, Orthographic and Hammer Aitoff projections. By the cursor you can define window, zoom, or you can get information about objects in the map

When the user define a coordinates window the window limits are rounded but only the data inside your coordinates limits are shown. See also DB_SCHART command if you want to work on a single catalogue.

REQUIRED Parameters

These parameter verbs are required for the execution of the task.

CATalogue   Opens Catalogue
RA   R.A. Window definition
DEC   Dec Window definition

SPECIFIC VERBS
The task uses all the verbs defined in section , moreover specific verbs are :

COOrdinates Set--up

To set the type of the coordinates in use in the map in order to have right label, valid response to cursor position 'CPOsition' query, and coherent plot of equators and poles in the plot map. The codes that can be entered are: 0 for equatorial (default), 1 for galactic and 2 for supergalactic coordinates.

Examples: CHA> COO 1

CPOsition Cursor

By this command you can obtain the equatorial, galactic or supergalactic coordinate values at the cursor position. Please note that the command COOrdinate sets the type of coordinates in use in the map.

EGEquator Grid and Display

When this parameter is set to 1 the equator (of the equatorial coordinate system) is drawn on the screen at the execution of the 'GRId' command The command COOrdinate sets the type of coordinates in use in the map.

EQColor Grid and Display

Set the color used in the drawing of the equator with the 'EGE', 'GAE' and 'SGE'. Use LUTs command to display available colors

GAEquator Grid and Display

When this parameter is set to 1 the galactic equator is drawn on the screen at the execution of the 'GRId' command The command COOrdinate sets the type of coordinates in use in the map.

GALactic Execution

When you have equatorial coordinates only, in a catalogue, you can draw a plot in galactic or supergalactic coordinates by this command. Of course you have more restrictions: The plot use an Hammer-Aittof projection and you can not use 'WINdow' or 'WHO' commands on the map. Note that, if you need supergalactic coordinates you must enter the parameter '1' after the command.

Example: CHA> GALactic 1

LISt Execute

Writes in a file the list of the objects that are present on the screen. The catalogue fields written are the current coordinates and the fields defined with 'SELect' command. Acts on all the opened catalogues.

PROjection Grid and Display

Defines the type of projection that you need. If this parameter is set to 0 the type of projection is selected by the program as a function of the sky area position. If you execute a 'WINdow' command the type of projection is automatically imposed by the sky zone and this parameter has no effect.

Types are:

Example: CHA> PRO 3

SGEquator Grid and Display

When this parameter is set to 1 the supergalactic equator is drawn on the screen at the execution of the 'GRId' command. The command COOrdinate sets the type of coordinates in use.

WINdow Cursor

Defines a new coordinates window by means of the cursor. The old value of 'RA' and 'DEC' are not modified by this command but the variable 'WRA' and 'WDEC' are updated. The command 'DWIndow' reset the window to the old value of 'RA' and 'DEC'. After this verb a 'GRId' command is executed with the new coordinate limits. Note that when you operate a 'WINdow' the parameter 'PROjection' has no effect.

XLAbel Grid and Display

Defines the type of label that will be written in the grid for the longitude (Right Ascension) axis. Please note that you can use a format: "hours-minutes-second" or a format: " degrees" for this coordinate setting the COOrdinate parameter (0 for hours, 1 or 2 for degrees). This parametr define the format of the labels.

The codes for the labels are:

XSTep Grid and Display

Number of bins and of labels in the grid on the longitude (Right ascension) axis. Note that the number of bins in the map can be different from the value that you enter with 'XSTep' because the grid routines tries to find a good solution using your number and a rounded value of steps between the labels. If you want to establish the number of bins enter your value preceded by minus sign.

Example: CHA> XSTep 6

YLAbel Grid and Display

Defines the type of label that will be written in the grid for the latitude (Declination) axis.

The codes for the labels are:

YSTep Grid and Display

Number of bins and of labels in the grid on the longitude (Declination) axis. Note that the number of bins in the map can be different from the value that you enter with 'YSTep' because the grid routine tries to find a good solution using your number and a rounded value of steps between the labels. If you want to establish the number of bins enter your value preceded by minus sign. Warning: using a small value of YSTep when you try a Mercator projection on a big map can give problems.

Example: CHA> YSTep 6

ZOOm Cursor

Executes a zoom with center at the cursor position and a magnification factor of two. You can use the command several times to magnify with a factor of four, eight , and so on. After this verb a 'GRId'command is executed with the new zoom factor, then the user must enter a 'DISplay' command to plot the objects. The command sets a scale value and you must use 'DZOom' verb to reset the original condition.

DB_CHART Summary of the commands

* = must be provided by the user command

Command Explanation Ref.

---- Execution

ALL Executes GRI and DIS on all cat. Verb DISplay Displays Data Verb EXIt Exits from task Verb GALactic Display data in galactic cord. Spec GO Executes the task Verb GRId Draws the grid Verb LISt Writes a data file Spec SYStem Return to VMS Verb TEXt Draws a string of text Verb

---- Set up and selection

ACTives Active a catalogue Verb * CATalogue Opens a Catalogue Verb CLOse Closes a catalogue Verb COOrdinate Sets type of coordinates Spec CONstrains Sets constraints on active cat. Verb CVAriable Defines cord. variables name Verb * DEC Sets Dec. coordinates limits Verb DWIndow Resets window condition Verb DZOom Resets zoom condition Verb LATitude Sets Latitude coordinate limits Verb LONgitude Sets Longitude coordinate limits Verb * RA Sets R.A. coordinate limits Verb WDEc Sets a window in Dec. Verb WLAtitude Sets a window on LAT. Verb WLOngitude Sets a window on LON. Verb WRA Sets a window in R.A. Verb

---- Grid

DGRid Resets default grid values Verb EGEquator Equatorial drawing flag Spec EQColor Color of the equatorial line Spec FONt Font type Verb GAEquator Galactic equator flag Spec GCOlor Color of the grid Verb LSIze Sets the label size Verb PROjection Sets the projection type Spec SGEquator Supergalactic equator flag Spec XLAbel Type of label on X axis Spec XSTep Sets the number of step in X axis Spec YLAbel Type of label on Y axis Spec YSTep Sets the number of step in Y axis Spec

---- Markers

COLors Color of the mark Verb LABel Sets the label type Verb LTYpe Sets the line type Verb MSIze Sets the size of the marks Verb SYMbol Sets the marks type Verb

---- Cursor

CPOsition Returns R.A. and DEC cursor pos. Spec SELect Fields listed in LISt e WHO Verb WHO To identify an object Verb WINdow Defines a window Spec ZOOm Executes a zoom Spec

---- Screen

CLEar Clear graphic device Verb CLS Clears command monitor Verb MONitor Number of rows in command monit. Verb NOWindow Doesn't draw window box Verb W2 Redraws graphic windows Verb

---- Help

? List of the commands Verb HELp Help of a command Verb LFOnt Shows available fonts Verb LUT Shows available colors Verb SHO Shows a parameter value Verb

---- Hard copy

HARd Executes a hard copy Verb HDEvice Defines hard copy device Verb HDImension Defines hard copy dimensions Verb

---- Log file

BREak Sets a break flag Verb DElete Deletes a log file Verb LOAd Loads an existent log file Verb NEXt Continues the load after a BREak Verb REMark Writes a string in the log file Verb SAVe Saves current log file Verb

See examples in figure



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