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The Data and Software

Because X-rays do not penetrate the Earth's atmosphere, X-ray telescopes must be placed in orbit above the atmosphere. A scientist who studies X-rays cannot build (or, more importantly, afford) his or her own X-ray satellite to collect the data needed. Satellites are often built by a national institution (such as NASA), and many scientists use each one. Scientists write proposals for what objects they want to look at and for how long. To make sure that the data can be accessed by scientists everywhere, the astronomical community has developed a standardized way of storing the data, in so-called FITS files (more on that later). Scientists use software developed specifically to work with FITs data from high energy telescopes. The Astrophysics Science Division (ASD) has developed a suite of software tools, called "ftools" (pronounced "eff-tools") for working with X-ray data in FITS file format. There are ftools for extracting information from the header, and for looking at and manipulating the data in the body of the file, and many other useful things.

Scientists at the ASD (or working remotely from locations all over the globe!) are able to use the ftools on a Unix or Linux computer operating system. The data sets involved are huge, often several Gigabytes in size. Generally, Unix systems are used to work with such large data sets, as Windows or Mac systems are not flexible enough to do the job. Because of these constraints, ASD programmers have developed a software program called "Hera" that allows users to install a small Hera module on their local machine and run ftools remotely on Goddard's machines. After setting up a Hera account, users can browse the ASD archives for data they want to study, store data sets on computers at Goddard Space Flight Center and run ftools (using ASD computers) on the stored data. Small files such as plots can then be saved to the user's local machine to study, print out and compare.

You will use a version of Hera adapted for use with this lesson. But the software tools are the same ones that astronomers use.

Imagine the Universe is a service of the High Energy Astrophysics Science Archive Research Center (HEASARC), Dr. Alan Smale (Director), within the Astrophysics Science Division (ASD) at NASA's Goddard Space Flight Center.

The Imagine Team
Acting Project Leader: Dr. Barbara Mattson
All material on this site has been created and updated between 1997-2012.

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