DB_SCHART

COMMAND TYPE : GRAPHIC

PURPOSE:

By means of this command you can display on a graphic terminal a selected sky area from one catalogue. Different values of a variable can be displayed with different marks.

DESCRIPTION:

This command draws a map of the objects selected from one catalogue inside a sky area defined by coordinates limits. In the display you can use different projections as: Mercator, Lambert, Orthographic and Hammer Aitoff projections. When the user works with galactic or supergalactic coordinates he must use the COOrdinate parameter at the appropriate value.

You can define a catalogue variable (character or numerical) and display with different colors and/or symbols the variable values. With the 'LIMits', 'PATtern', 'SAMple' and 'SIZe' commands you can define how to link the display markers to the values of the catalogue field.

Using the cursor you can define Window, Zoom, or you can get information about sky objects. When you define a coordinates window the window's limits are rounded, but only the data inside your coordinate values are shown.

See also DB_CHART command if you want to work with many catalogues at one time.

REQUIRED Parameters Verb

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

CATalogue  Open Catalogue
RA  R.A. Window definition
DEC  Dec. Window definition
VARiable  Catalogue Variable
LIMits *  Variable value to be displayed (numerical )
PATtern *  Variable patt. used in the display (character )
Maximum   Max value on a numerical 'VAR'

* one of these must be supplied

SPECIFIC VERBS

The task uses all the command verbs defined in section ; moreover specific verbs are :

ACTive Set-up

In other tasks this command is used to select the active catalogue; in this task you have only one catalogue opened. This command is used to indicate one of the eight 'LIMits'/'PATtern' that you can set. If you want to change the value, or the symbol of the 'LIMit' number N you can use 'ACTive' command and then change that value only.

CPOsition Cursor

With the cursor you can get the coordinate values at the cursor position.

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

Sets the color used in the drawing of the equators set 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. You have also other 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 objects that are displayed on the screen. The variables are: the right ascension and declination coordinates and the variables defined in 'VAR' and 'SELect'

LIMits Variable Parameter

With this verb you can define the range of the numerical value of the catalogue variables that must be displayed using the different symbols. The maximum number of 'LIMits' that you can define is eight. 'SAMple' defines the type of relation that you can have between data and symbols. This verb can be used in two ways. If the verb is followed by a number the active limit only is changed, if there are N values the 'LIMits' from 1 to N are updated.

Examples: SCH>LIM 1.5 2. 3. 5.5 7. 12. 20.

PATtern Variable Parameter

With this verb you can define the strings that you find as catalogue 'VARiable' and that must be displayed. The maximum number of 'PATtern' that you can define is eight. 'SAMple' defines the type of relation that you prefer. This verb can be used in two ways. If the verb is followed by a number the active pattern only is changed, if there are N values the 'Patterns' from 1 to N are updated. The key OTHER collects all the other objects.

Examples: SCH>PAT Sa Sb Sc S0 DWARF E OTHER

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

SAMple Variable

Defines how the 'LIMits'/'PATtern' are used in the selections. On numerical value 'SAMple' can be 0-1-2. The catalogue value will be displayed with n-th symbol if:

Note that you can see 'MAXimum' as LIMit(9)

The parameter 'SAMple' can have the values 0-1. The catalogue string will be displayed with N-th symbol if:

SAMple
0   PATtern(N)   = string
1   PATtern(N)   match string

SIZe Variable

Defines a size in the numerical selection: see 'SAMple' verb for more details.

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.

VARiable Variable Parameter

Defines the catalogue variable that you use in the graphic selection. If 'VARiable' refers to a numerical value you must define 'MAXimum' and 'LIMits', otherwise you must define 'PATtern'.If you answer '?' at the prompt you will get a list of available variables on the catalogue.

Example: SCH> VARiable MAG

WINdow Cursor

Defines a new coordinates window by the cursor. The old value of 'RA' and 'DEC' are not changed by this command but the variable 'WRA' and 'WDEC' are updated. The command 'DWIndow' resets the window to the old value of 'RA' and 'DEC'. After this verb a 'GRId' command is executed using the new coordinate limits. To display the objects you must enter a 'DISplay command'. 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 marks and of labels in the grid on the longitude (Right ascension) axis. Note that the number of marks in the map can be not the same of 'XSTep' 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 set the number of marks enter a minus sign before the value.

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 marks and of labels in the grid on the longitude (Declination) axis. Note that the number of bins in the map can be not the same of 'YSTep' because the grid routine tries to find a good solution using the number that you enter and a rounded value of steps between the label. If you want to set the number of bins enter a minus sign before the number. Warning: when you use a Mercator projection on a big map a little value of YSTep 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. To plot the data enter a 'DISplay' command.

The command sets a scale value and you must use 'DZOom' verb to reset the original condition.

DB_SCHART Summary of the commands

* = must be provided by the user

---- Execution

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

---- Variables

ACTive Actives the mark Spec *) LIMits Range of VAR Spec * MAXimum Maximum value of VAR Verb MINimum Minimum value of VAR Verb *) PATterns Strings used in the selection Spec SAMple Type of selection Spec SIZe Size of numerical selection Spec * VARiable Variable used Spec

---- Set up and selection

* CATalogue Opens a Catalogue Verb CLOse Closes a catalogue Verb COOrdinate Sets type of coordinates Verb 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 and display

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 Spec 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 Clears graphic device Verb CLS Clears command monitor Verb MONitor Number of row 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 an 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

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