The HEASARC Help Desk and FAQ

The HEASARC is a source of gamma-ray, X-ray, and extreme ultraviolet observations of cosmic (non-solar) sources. This site provides access to archival data, associated analysis software, documentation, expertise in how to use them, as well as relevant educational and outreach material. This site also provides many general astronomical tools such as SkyView, which allows users to obtain multiwaveband images of the sky, and the Browse and the Virtual Observatory DataScope interfaces, which allows users to identify and/or select resources from the HEASARC and many other archives all over the world. To access archival data from other wavebands, you can also visit the NASA Infra-red (IRSA), Microwave Background (LAMBDA, the CMB part of HEASARC), and UV/optical (MAST) archives, as well as the astrophysics service of the NSSDC.

The LAMBDA (Legacy Archive for Microwave Background Data Analysis) component of HEASARC is a "multi-mission NASA center of expertise for cosmic microwave background (CMB) radiation research; it provides CMB researchers with archive data from cosmology missions, software tools, and links to other sites of interest".

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Related FAQs

  • ASCA FAQ for non-experts
  • Fermi FAQ
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  • RXTE FAQ - data analysis, software and data processing
  • Swift FAQ - software, data obs & analysis, etc.
  • WMAP FAQ for non-experts
  • XMM-Newton FAQ - observation enhancement
  • High-Energy (X-ray and gamma-ray) Astronomy

    Many of these questions are answered in more detail in the HEASARC Cookbook.
  • What high-energy astronomy data are available at the HEASARC?
  • What format are HEASARC data files in?
  • How do I download data from the HEASARC?
  • How do I get started in X-ray or gamma ray data analysis?
  • How to acknowledge data obtained from the HEASARC
  • How do I get the X-ray flux of my favorite object?
  • How do I convert X-ray flux/energy/etc. units to those used in my field?
  • How do I do anything with these "event lists"?
  • Which X-ray satellites have looked at my favorite source?
  • Which satellite can do the science I'm interested in?

    Cosmological Microwave Background (CMB)

  • What CMB data are available from LAMBDA?

    General, Educational and Public Outreach

  • Where can I find nice images for my presentation?
  • Where can I find teaching resources for my high school or college course?
  • How do I get to the HEASARC?
  • Why wasn't the astronomical name that I entered recognized as valid?
  • What educational resources does the HEASARC have?
  • Tell me about black holes (or other astrophysical phenomena)
  • Where can I find nice images?
  • How do I credit an image found on these pages? What about copyright?
  • Can I purchase printed copies of the images I find on this site?

    General Information

  • Tour the HEASARC Web site
  • Get plugins for PDF, PPT, QuickTime, etc.
  • Goddard Space Flight Center FAQ

    High-Energy (X-ray and gamma-ray) Astronomy

    What high-energy astronomy data are available at the HEASARC?
    The HEASARC archives contain data from orbiting high-energy astrophysics missions which observe the cosmos in the EUV, X-ray and gamma-ray bands, in addition to catalogs of sources at other wavebands (Some exceptions to this are XMM-Newton, Swift and INTEGRAL for which the HEASARC has datasets from optical/UV instruments onboard these satellites). The HEASARC also has a large database of tables and catalogs of many types, e.g., observation logs, object catalogs, surveys, etc. A listing of these 700+ data tables can be found in the
    Browse area. These tables are also available in a downloadable ASCII format by visiting our FTP area. The HEASARC does not contain data from ground-based observatories such as the VERITAS array of atmospheric Cerenkov telescopes, nor from balloon or sounding rocket payloads, with a few exceptions, e.g., the soft X-ray data from 10 University of Wisconsin sounding rockets flown in the 1970s are archived here. Nor does the HEASARC have any cosmic ray datasets: such data are archived at a variety of sites, including NSSDC and SPIDR, and mission archives such as the ACE Science Center and the SAMPEX Data Center

    What format are HEASARC data files in?
    The majority of HEASARC data are stored in
    FITS format. FITS is the data format most commonly used within astronomy. The fv package provides a simple way to view FITS files.

    How do I download X-ray or gamma-ray data from the HEASARC?
    The HEASARC's
    main archive page has 9 interfaces with various purposes and degrees of sophistication. These are designed to help you identify datasets of interest based on various astronomical and mission-based criteria and then to allow you to download these data. If you are already familiar with the structure of our archive, you can also get direct access to the data directories through http or ftp.

    How do I get started in X-ray or gamma-ray data analysis?
    The HEASARC's
    XANADU package supports spectral, temporal and spatial analysis of high-energy data and has been developed to be quite portable. You can use this immediately on the high-level products in the HEASARC archive. The FTOOLS provide more discrete analysis tools including mission-specific analysis pipelines. These two packages along with some other useful software have been consolidated into the HEAsoft package.

    How do I acknowledge data obtained from the HEASARC?
    If using the HEASARC service made a significant contribution to a research project, please make the following acknowledgement in any resulting publication:

    "This research has made use of data, software and/or web tools obtained from NASA's High Energy Astrophysics Science Archive Research Center (HEASARC), a service of Goddard Space Flight Center and the Smithsonian Astrophysical Observatory."

    How can I quickly get the X-ray count rate or flux of my favorite object?
    Use
    Xamin or Browse to search for your object in X-ray object catalogs. The X-ray master catalog may be particularly useful in this regard as it contains basic information from more than hundred individual X-ray source catalogs. If only count rates are available, you can use WebPIMMS to estimate the corresponding physical fluxes, given an assumed spectral model.

    How do I convert X-ray flux/energy/etc. units to those used in my field?
    Our
    W3PIMMS service can convert from the arcane units used in some X-ray papers (and a few of our catalogs) to more standard units. A general energy converter also helps translate energy units.

    How do I do anything with these "event lists"?
    High-energy instruments often count individual photon "events." To create the maps or time-series with which you may be more familiar, use our
    FTOOLS package. Many of our high-level software tools will do this for you automatically!

    Which X-ray satellites have looked at my favorite source?
    You can use either
    Xamin or Browse to search the HEASARC's collection of observation catalogs for individual satellites, or the basic interface can search all of the satellites for which we have archival data in a single step.

    Which satellite can do the science I'm interested in?
    The HEASARC maintains extensive
    documentation for each mission and has a number of tables which compare capabilities.

    Cosmological Microwave Background (CMB)

    What CMB data are available from LAMBDA?
    A growing collection of CMB data, software and web tools is available from LAMBDA, ranging from data from NASA's two flagship CMB missions COBE and WMAP, to data from balloon-based experiments such as BOOMERanG, to data from ground-based facilities such as SPT and ACT.

    General, Educational and Public Outreach

    Where can I find nice images for my presentation?
    A growing collection of
    high-energy science results (images, spectra and light curves) is available. High-resolution versions of these images are being added regularly. Also visit the HEASARC Picture of the Week and Astronomy Picture of the Day sites.

    Where can I find teaching resources for my high school or college course?
    The HEASARC's
    outreach programs provide many free educational resources for all levels. Images sorted by object type and by mission are available, as well as educational resources like the Imagine the Universe! site. Our newly-added resources for scientists provides links to presentations given by your peers and at various x-ray astronomy courses.

    How do I get to the HEASARC
    If you wish to visit the HEASARC, send an email message to visitor@athena.gsfc.nasa.gov. Please let us know when you wish to visit, if you are a US citizen, and what you hope to accomplish while you're here.

    Why wasn't the astronomical name that I entered recognized as valid?
    Many of the HEASARC's on-line tools allow the user to enter either a position or a name. To `resolve' the name, i.e., to find the position associated with an object name, the HEASARC generally uses either the Simbad or the NED name resolver services. So the question posed above can be rephrased as `Why can't the name resolvers find the name that I entered?'

    The most likely answer is that you mis-spelled the name! Try another alias for your object if you know of one, or avoid using the name resolvers at all, by using the position rather than the name. In either case, make sure that you specify a search cone radius around the specified location which is large enough to account for any possible positional uncertainty.

    Another possibility is that the name you used was considered to be non-standard or ambiguous by the name resolvers. This can happen sometimes because astronomers don't always adhere to the naming conventions recommended by the CDS Dictionary of Nomenclature of Celestial Objects. For example, the names of SNR are often given in papers using G prefixes, e.g., "G 351.2+0.1", but these are not the recommended form for SNR, which is in fact "SNR 351.2+00.1". Notice that as well as the SNR rather than the G prefix, there is an extra character in the galactic latitude part of the name. (As a matter of fact, names with G prefixes are reserved by Simbad for high proper motion stars from the Giclas Catalog and should, in general, be avoided due to their ambiguity).

    Finally, there is a rather small chance that your object has been accidentally omitted from the name resolvers' lists of sources. If so, we suggest that you contact their maintainers directly: for Simbad, email to question@simbad.u-strasbg.fr, or for NED, email to ned@ipac.caltech.edu (remember that NED only maintains lists of extragalactic objects).

    What educational resources does the HEASARC have?
    The HEASARC's
    outreach programs provide many free educational resources for all levels.

    Tell me about black holes (or other astrophysical phenomena)
    The HEASARC's
    outreach programs provide many free educational resources for all levels.

    Where can I find nice images?
    The
    NASA Image Exchange is NASA's centralized source for its imagery (and also has a good discussion of copyright and other restrictions on re-use of images). At the HEASARC, a growing collection of high-energy science results (images, spectra and light curves) is available. High-resolution versions of these images are being added regularly. Images of high-energy astronomy satellites are also available. For the most recent scientific images from high-energy astrophysics, visit the HEASARC Picture of the Week page. The Astronomy Picture of the Day has a new general-astronomy image each day.

    How do I credit an image found on these pages? What about copyright?
    Many of the images on the HEASARC Web site have credits written on or near them. The general NASA policy on copyright issues and the use of NASA imagery by others is available
    here. If an image has a copyright, you should contact the copyright holder for permission to use the image. If you do not find a credit, please contact us requesting the credit. Please include the full URL of the page where you found the image.

    Can I purchase printed copies of the images I find on this site?
    We do not have the facilites to reproduce and mail images to you. You are welcome (when the image has no copyright) to download and print out your own version. Often, high-resolution versions of image are available and linked explicitly for this purpose.



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    Last modified: Thursday, 12-Dec-2013 09:13:28 EST