Workshop aips++ Project Exercise 1

The goal of this excercise is to make a Glish script to use various aips++ tools to

Access an image
Find the strongest point sources
Create a skycatalog from this list of sources
Display the image and overlay the source locations

YOu should be logged into nelle in a directory like

/DATA/NELLE_1/synwork/aips++/group1

The aips++ image to work with is called 'mosaic'

Make sure the DISPLAY environment variable points to the computer you are sitting in front of. E.g.

% setenv DISPLAY hydrus:0

Required Tools

To achieve the above goals, you will need to use a small variety of aips++ tools, and write just a few lines of Glish to string them together.

You put your Glish code in a file with suffix ".g". E.g. ex1.g Use your favourite editor to create that file. Then you load and run that script with

% glish -l ex1.g

The tools that you will need are all described in the User Reference Manual. This manual is structured by package, module and tool (going to finer granuality).

You will find the Image tool in the General package, in the Images module of the User Reference Manual. This tool is used to gain access to images and manipulate them. You will need the "image" constructor and the "view" function. For example

% glish 
include 'image.g'                # Include Image tool script
im := image('mosaic')            # Access image
im.summary()                     # Summarize header information
im.view()                        # Display it
im.statistics()                  # Statistics

To find the pointsources, you need to use the Image tool function called 'findsources'. For example :

include 'image.g'
im := image('mosaic')
cl := im.findsources();

It creates what is called a Componentlist tool. You can find out about those in the Package Synthesis in the Componentmodels module. But you don't really need to do anything with it apart from convert it to a skycatalog table.

include 'skycatfromcomponentlist.g'
#
cl := im.findsources();
skycatfromcomponentlist ('overlay.tbl', cl)

This makes an aips++ Table called 'overlay.tbl' from the Componentlist tool 'cl'. This table is in the correct format for the Viewer display tool to recognize as a Skycatalog overlay.

To have a look inside of it, use the generic Table tool (Package Utility, Moduile Tables).

include 'table.g'
t := table('overlay.tbl')             # Make Table tool
t.browse()                            # Browse GUI

The last thing to do is start the Viewer display tool to display the image and the Sky catalog as an overlay.

include 'viewer.g'
dv.gui()               # Including the script above makes the 'dv' Viewer tool for you

Now, from the data manager, select 'mosaic.app'. Then click 'Raster Image' (to the right) and the image will appear in the display panel. Then select 'oiverlay.tbl' and click 'Sky Catalog Overlay' (to the right) and little markers will appear on the display panel. At the bottom left, press 'Adjust'. Use the GUIs that appear to turn on axis labels and to fiddle about with the sky catalog overlay markers (turn on source names annotation, mve labels around change colours). Finally, use the QUERY entry of the overlay adjust GUI to restrict the displayed markers in certain ranges (e.g. Long > 13).

If you get desperate, you can find my solution to this exercise here.