sourceplot - display a plot of astronomical sources on adjustable axes


    sourceplot [--help | --version] [--date YYYY-MM-DD]


Source Plot was created to help observers decide which sources to observe at particular times to optimise the observing time at the telescope. The main purpose of this program is to plot the movement of a source throughout the night. The movement can be plotted by the source's elevation, azimuth, parallactic angle, or by time.


Source Plot is designed to display the path of a source throughout a night. This path can be displayed in several ways, using Time, Elevation, Parallactic Angle, and Azimuth as the different axes. The sources can either be taken from a catalog or manually inserted. The first thing most observers will want to double click on is a source in the Catalog Window, which will plot that source. Currently the only moving sources that can be plotted are planets, the Sun and the Moon, which can be added via the 'Planets' button in the Edit Window.

Command Line Options

--help | --man

Show this documentation.


Show version information.

--date YYYY-MM-DD

Select initial date.

Plotting Window

The Plotting Window contains the actual plot and has control over the other windows. The display itself has several features. Each colored line in the Plotting Window is associated with the source with the same color in the Edit Window. In the event that two lines have the same or similar color, moving the mouse over a plotted source will highlight the source in the Edit Window. The large dot along the plotted source is the position of the source at the current time, called from here on a 'location dot'. These dots are updated automatically as time passes. Moving the mouse over a location dot will display the elevation and azimuth for the source in respect to an RA-Dec graph, where Dec is the y-axis. This feature does not work in the Azimuth-Elevation graph. The small dots along the plotted lines are 15 minutes apart, showing the precise time the source will be at a given location.

There are several buttons in this window. Starting from the left, here's an explanation of each:


Opens a window in which the relevant telescope, x-axis and y-axis can be changed. The time the plot is centred around can also be changed. To apply these changes without closing the window, press the 'Apply' button.

UT Date

A window will appear with the current UT Date in it which can be modified to see future or past dates.


This button will open the Edit Window if it is closed. This button becomes disabled when the Edit Window is open.


Like the 'Edit' button, the button opens the Catalog Window if it is closed. This button will be disabled if the Catalog Window is open to prevent more than one Catalog Window from being created.


See "Printing the Graph" for a description of this button.


Exits the program, closing all associated windows.

Edit Window

This window contains the list of sources chosen by the observer. Only the sources that are active will be shown in the plot. The first thing that should be known is how to select sources so they can be added, deleted, or deactivated. To select a source, single click on it in the Edit Window. The source will turn red indicating it has been selected. Several sources can be selected by clicking on each one individually. To deselect a source, single click on the source again.

There are several small features in this window. Moving the mouse over a source in the Edit Window will highlight its plotted line in the Plot Window. To edit a source's coordinates, double click on it. A window will appear in which the source's information can be changed. The final set of features require the use of the Edit Window Buttons. The following is a description of each, starting from the left:


This button will activate or disable the selected sources. Disabled sources will not be displayed in the Plotting Window

Delete All

This button will remove the sources in the Edit Window. It will not delete the source from the Catalog Window.


The selected sources will be removed from the Edit Window.


This button will undo the last major command. Major commands are considered to be deletions, additions, and source coordinate changes.


This will allow a source to be created manually, inserting the appropriate coordinates and a name. The new source will be added to the list in the Edit Window and to the plot. The RA/Dec coordinates can be entered with spaces or colons separating the parts. If only the first one or two parts are inserted, the remaining parts will be filled with 0's.


By pressing this button, a list of the planets will appear. Selecting one will add it to the list of sources in the Edit Window and to the plot.


This button will close the Edit Window. It can be re-opened by pressing the 'Edit' button in the Plot Window.

Catalog Window

The Catalog Window is provided by Tk::AstroCatalog (part of the Astro::Catalog package). Through it, the observer is able to add sources from a catalog file to be plotted. The JCMT unified source catalog, which is included with this program, is initally shown in the Catalog Window. There are several features that are not obvious. To select sources in the Catalog Window, click the mouse button once over top of it. The source will turn red to indicate it has been selected. Several sources can be selected in this way, creating a list of selected sources to do actions on. To deselect a source, click on it a second time. Double clicking on a source will add it and all the selected sources to the Edit Window where the sources will be plotted.

The following are explanations of the features contained within the buttons on the Catalog Window:


The 'Catalogs' button will allow the observer to load a default catalog or to load a catalog from file. If the file is chosen, a window will appear in which to find the desired path and file. The path and file can be entered manually in the 'Catalog file:' field. The default catalog, to be loaded when the 'Default Catalog' menu entry is selected, can be changed by setting the ASTRO_CATALOG_JCMT environmental variable by typing setenv ASTRO_CATALOG_JCMT /path/catalog. Although Source Plot has been programmed to accept different variations of catalogs, the Catalog Window loads catalogs in the JCMT pointing catalog format.


'Rescan' rescans the currently selected catalog, displaying any entries that may have been lost in a search.

Using 'Search' will display a window in which the user can fill one or more fields in which to search for a specific source. If any of the fields is not filled in, the program will ignore that field and search based on the other fields. If only part of a field is known, the program will display any sources containing the partial information. For example, if the RA starts with '5' and the Dec begins with '-9 45', type '5' in the RA field and '-9 45' in the Dec field and the resulting search will display all the sources that have an RA starting with '5' and a Dec starting with '-9 45'. Since the other fields were not used, the search will not be limited by them.


'Add' adds the selected sources to the Edit Window.


To close the Catalog Window, press 'Done'. It can be re-opened by pressing the 'Catalog' button in the Plot Window.

Printing the Graph

Once all of your sources are plotted, press the 'Print' button in the Plotting Window. A window will appear. Source Plot will let you print to a printer or to a file. Select the method you prefer by pressing the diamond to the left of that option. If using the 'To File' method, fill in the 'Filename' field with the path and filename desired. If using the 'To Printer' method, the command to print can be changed in the 'Printer Command' field. The default command is 'lp'. Additional arguments can be added to the line or a totally different command can be used by replacing this line with the desired command. For example, to print to a specific printer, just add '-d printer' after 'lp'. When everything is ready, press 'Print'.

Elevation vs Azimuth Mode

The Elevation vs Azimuth Graph was created to better show the distance between sources in the sky. The plot will be shown in this mode if the selected axes are azimuth and either elevation or air mass.

The elevation is indicated by the circular lines, with the white outside circle 0 degrees and the middle of the graph 90 degrees. The azimuth rotates around the circle, 0 degrees at the top and 180 degrees at the bottom. Like the other graphs, the large dots on the lines represent the position of the source at the current time. The small dots are 15 minute intervals apart. The times written on the graph around the 30 degree mark for each source is the time, in HST, that the source will be passing through that point.



Stores the settings from the Options Window when 'Save Setting' is selected. This file is read to configure sourceplot when it starts up.




Casey Best (University of Victoria), Pam Shimek (University of Victoria), Tim Jenness (Joint Astronomy Centre), Remo Tilanus (Joint Astronomy Centre), Graham Bell (Joint Astronomy Centre / East Asian Observatory).


Copyright (C) 2018 East Asian Observatory. Copyright (C) 2012 Science and Technology Facilities Council. Copyright (C) 1998, 1999 Particle Physics and Astronomy Research Council. All Rights Reserved.

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see <>.