RHESSI OBJECT PARAMETER DEFAULTS

Kim Tolbert, 07 November 2008

I.  Setting Your Own Defaults

There are a number of ways to start the RHESSI software with custom defaults.

1.  Set your preferences when you create the object:  You can use keywords to set parameters in the call to create an object.  For example,

obj = hsi_image(/uniform, image_dim=32)

obj = ospex(spex_uncert=0.0)  

2.  Script files:  Create the object in a script, and then set any parameters you want.  For example:

obj = hsi_image()

obj->set,/uniform

obj->set,image_dim=32 

3.  Script files from the GUI:  Use the Write Script button in the spectrum, image, or ospex widget to create a script after you've set the parameters you want in the widget.  Then run the script to create an object with the same settings.

4.  Pass an existing object into the hessi GUI:  To start the GUI with an object already set up with your preferred settings, pass the object into the GUI.  For example, after you've created an object called, for example, obj from the command line using one of the methods above, start the GUI via

hessi,obj

This works for image, lightcurve, spectrum, monitor rate, or observing summary objects.  Only one object can be passed into the GUI.  Whatever time is set in that object will be used for the overall observing time interval in the GUI and will be transferred to each of the other objects within the GUI.

As always, to manipulate the objects used internally in the GUI at the command line, you can retrieve any of them via the hessi_data command.  Type hessi_data for instructions on how to retrieve them.

5.  Set default parameters when you start the GUI:  When you start the hessi GUI, any keywords you pass in as arguments will be set into the objects.  For example:

hessi, obs_time_interval=['20-Jan-2005 06:45:04.000', '20-Jan-2005 06:45:08.000'], $

          image_alg='clean', image_dim=32, sp_energy_bin=22

This command will set those parameter values into the image and spectrum objects used in the GUI.

REMINDER:  If you're not sure what the name of a parameter is, consult the tables of object parameters for rhessi objects and the ospex object.  And if you still can't figure it out, send me a message.

II.  How to Use Old Defaults

On March 26, 2007 we changed some of the values for default parameters for the RHESSI objects.  We overlooked the problems this would cause with existing scripts that would produce different results, and we apologize.  We've added the following two ways to create objects with the old defaults (pre March 26 defaults):

1.   Keyword option:  When you create the hsi_image, hsi_spectrum, or ospex object, or when you start the hessi GUI, use the /pre_apr2007 keyword:

obj = hsi_image (/pre_apr2007)
obj = hsi_spectrum (/pre_apr2007)
obj=ospex (/pre_apr2007)

hessi, /pre_apr2007

OR

2.   Set the environment variable pre_apr2007 to 1 before creating the image, spectrum, or ospex object.
 

-        In a Windows .bat file (e.g. sswidl.bat):  set pre_apr2007=1

-        In a Unix script file:  setenv pre_apr2007 1

-        Within SSWIDL, setenv, 'pre_apr2007=1'

Either of these methods will create objects that have the defaults that were in effect before the March 26 change.  If you have a lot of scripts that you want to run with the old defaults you might want to use the environment variable option so you don't have to edit all of your scripts.  If you set the environment variable in a startup file, REMEMBER that you set it so that you can unset it for new work.

If we make changes to default values in the future, we'll add other keywords so you can select which defaults you want.

Note:  In the March 26 set of changes, the most controversial is the change from uniform to natural weighting for Back Projection and CLEAN images.  Of course you can always set this parameter explicitly to your preferred setting, without invoking all the pre March 26 defaults, via the SET command.  Brian Dennis will be sending a message soon with a detailed discussion of the effects of natural vs. uniform weighting on CLEAN images.