| Neutron Stars in
Binary Systems |
Using Hera
The Hera program allows the user to run the software ftools to manipulate FITS
files from a local computer on a machine at Goddard Space Flight Center on data
stored in the user's temporary Hera account (again on a Goddard computer). Data sets are also included with the education version of college Hera. Now that you have installed the
Student Hera module, you can begin to use the Hera tools to examine and analyze X-ray
data.
A typical Hera analysis session usually consists of two distinct operations,
selecting the data in your Hera account and then selecting and running a tool to
use within Hera to analyze the stored data. The output will be displayed on your
computer, and you can print out or save plots and other output locally.
To log in the first time, click on the Student Hera icon on your desktop (when you install Hera, the install wizard will put a shortcut on your desktop). A login window will appear, which looks like the graphic below. When you click on the "login" button, the Hera module on your computer will connect to Goddard's computers. When the connection is made, you are ready to begin. A user name will be assigned to your computer so that you can access your account later. Your account will remain active as long as you login at least once every 30 days. When you want to log in again, you will again click on the Student Hera icon. The login window that comes up should have your unique Hera login displayed, and you can click on "login" and access your account.
Note: Because of the large number of requests that the server must process,
some functions, including logging in, may run slowly.
When you are logged in, the
main Hera window (click for sample image) will appear, which is divided into 3 main areas:
- Available Tools: Located in the upper part of the window, this section
provides a list of all available software tools. Below
the tools are two buttons: "run" executes the selected tool while "help" provides a detailed description of the tools and its parameters. When you click the "help"
button, a window with the detailed help will appear. You will be able to search
this window for specific text.
- Available FITS File List: You will find this part in the upper
right-hand part of the window. This section allows you to view a listing of
selected data sets available on the Hera Server. (Flexible Image Transport
System or FITS is the standard file layout for astronomical data.) There are two
separate areas; a list of read-only data sets, and a list of output files that you create while running your Hera session. Output files that
you create can be deleted by selecting them and clicking the "delete" button.
- Description: Short descriptions of the tool
selected are displayed in the bottom section that spans the length of the
window. Try clicking on a tool in the upper left and see the description given in the text window.
On some machines you may need to resize this window in order to see the whole
thing.
- You will first need to click on a data set in the upper right window to
select it.
- Then you can choose a tool in the left window.
- To execute the tool you just need to click on the "run" button below the tools window.
- When you run a tool, a parameter box will appear that requests necessary information to make
the tool work.
These parameters may have values already there, but assume
that they are not correct. These default values, or other incorrect values,
can cause your computer to stop responding. The data set and data set directory
should be filled in already. Any needed parameters will have a blank white space to be filled in. Parameters with default values will be grey (though these can be overwritten). The guided tutorial that follows often has suggested starting parameters. Using these parameters will help make the exercises more clear,
since a bad choice of parameters can lead to confusing or unexpected results!
Once the parameters are filled in you can click on "run" to run the tool. There
is also a "save these parameters" button, which can be useful (so that you do
not have to retype in all of the parameters, when you are varying just one, for
example).
If you have any problems, comments, or suggestions regarding Hera, please use the 'Mail' button in the lower right corner of the Hera command window.
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