Report of HEASARC Users Committee

January 19, 1995


The User Group heard an impressive catalog of developments, improvements, and a solid record of achievement by the HEASARC over the past year. We find the HEASARC to be a model of efficiency and scientifically well directed priorities. The unanimous conclusion of the User Group is that the HEASARC has performed its work remarkably well on the limited funds available, and with an ever increasing burden of responsibility.

We find the HEASARC is far more than the sum of its parts. In addition to several terabytes of archival data (continually expanding in ingest, and continually increasing in export requests), it is a unique and invaluable source of assistance (through software tools and personal assistance/troubleshooting) without which much research in High Energy Astrophysics would be impossible. All of this is achieved at only a slight overhead increase over the cost of maintaining a pure archival activity.

In the following sections we record our formal recommendations, comments on the presentations, and summary of the executive session.

Recommendations & Comments

  1. For all datasets being provided to the HEASARC through the ADP process, proposers should be required by the NRA to adhere to standard HEASARC data formats.

  2. When proposals are accepted which will send data to the HEASARC, that information should be transmitted to the HEASARC by NASA Headquarters as early as possible, to allow for resource allocation at the HEASARC. (We also suggest the possibility of technical evaluation of proposals for relevant proposals by the HEASARC.)

    Sethanne Howard and Guenter Riegler both suggested that the HUG develop wording to implement the above two points, for inclusion in the NRA. I will distribute a draft for comment.

  3. Use of the NSSDC archive as both the final archive and the operational archive for XTE is an excellent use of facilities to maximize the overall NASA efficiency. We encourage the NSSDC and HEASARC to enlarge areas of joint activity, while retaining the viewpoints for which each was created (secure archival storage for the NSSDC, and active science use of archival material for the HEASARC.)

    We recommend to NASA HQ that the project only be allowed to purchase archive hardware sufficient to store one year of data for caching purposes.

  4. The ASC is critical to future high energy astronomy data archiving and analysis. We encourage cooperation between HEASARC and the ASC, and suggest inclusion of ASC personnel in the HUG and FITS committees.

    We specifically recommend the HEASARC coordinate development of a broader FITS oversight committee (based on the successful internal one) which reaches out to all major high energy astrophysics organizations, to ensure the broadest possible commonality of data and software.

  5. FITSIO is an important component in the effort to standardize data formats and software. The main negative comment has been a claim that FITSIO is less efficient than other packages. We recommend that the FITSIO team compile benchmarks, and attempt to find people with quantitative data about any FITSIO inefficiency.

  6. Distributing data on CD-ROMs is viewed as useful scientifically, and useful as an advertising medium for the HEASARC. Within the current level of activity we endorse the CD-ROM distribution.

    Our suggested priority for future CD-ROMs is imaging data, which is less efficient to be retrieved by network. The next two projects are the Einstein MPC data (which are spectra), and a `Best of Exosat' (which is a mixture of compressed images and spectra).

  7. XSPEC has become an accepted standard for X-ray spectral analysis. Papers using it are common, but are forced to be improper by the lack of a published reference. We requested Keith Arnaud write a paper in a refereed journal, describing XSPEC, which can be used as an XSPEC citation.

  8. The HEASARC has been greatly successful in obtaining, archiving and reformatting archival datasets to make them publicly useable. While we recognize that the following datasets are generally inaccessible for political reasons the HUG calls on the HEASARC, NASA and our respected colleagues across the world to make available to the HEASARC the following data.

    • ROSAT All-Sky Survey Data This is a great observatory with a tremendous wealth of data. It can only be properly used if it is studied by a much larger number of scientists. Moreover future X-ray measurements may be compromised if this archival dataset remains inaccessible.

    • Gamma-ray Burst Data from PVO, Ulysses, Ginga, ISEE-3 The study of Gamma-ray bursts is an extremely exciting topic. The number of events is small, but these data have been in hand long enough to reach a non-proprietary status.

      Note added: Kevin Hurley has just delivered the Ulysses data to the HEASARC. Here are Kevin's notes on the data:

      For your information, we have just delivered almost 4 years of data to the NSSDC. This consists of high time resolution (0.25-2.0 s resolution), real-time 25-150 keV count rates, in which almost all the bursts may be found. The NSSDC negotiated for this data and actually did not want the higher time resolution (8 or 32 ms) triggered data. If there is a strong interest in obtaining the triggered data, we could discuss it. (Please note that, as an ESA/NASA mission, no obligation was placed on us to deliver anything more than the data we are giving to the NSSDC.) The only problem we might have is that, like everyone else, we are being ramped down, so we could not provide a great deal of support.

    • Sigma/Granat & Sigma/ART-P We are concerned that the storage facilities for these data in Russia may be inadequate. The HEASARC should investigate with the Russians and French if the HEASARC can play a role in saving these data.

  9. Steve Drake described the data access and retrieval from the HEASARC, and commented on the rapid growth of WWW access. A component of this growth is due to highly inexperienced or naive users who ask extremely elementary questions. The HUG encourages the growth of the use of HEASARC data in educational applications, but suggests that an education hotseat helpline be developed, either with money from educational initiatives, or by cross-linking to an existing educational hotseat.

  10. The HEASARC should strive to make accurate, up-to-date observing logs available as soon as possible for the active missons (currently ASCA and ROSAT). It would be desireable to have accurate short term timelines from the mission schedules, but if mission communication problems preclude this, then at least a log containing the processed data should be as current as the processing effort.

  11. When the HEASARC alters FITS format keywords in archives, or data archive filenames, it should actively inform the community in advance of such changes, and consider the community response before making the change.

  12. The HEASARC should add a `What's New' hypertext link to the HEASARC home page, and update it periodically with the latest dataset additions, software changes or other developments. We ask that this link be updated shortly before the HUG meeting, so that the HUG can test the new features.

  13. The HEASARC should consider implementing a tool similar to `Presto' in use at the HST. This will track the current state of an accepted proposal, and provide pointers to the reduced data products.


The following are brief notes from each presentation

  1. Nousek- Kirk Borne joins the HUG, replacing Knox Long. He will keep the HUG in touch with HST archiving activities.

  2. White- Big challenge to HEASARC is prospective XTE archive (3.5 Tb!) XTE will archive directly to NSSDC, without a project archive.

  3. Whitlock- Great progress on data archiving and reformatting. See earlier recommendations to ease this task.

  4. Pence- New checksum keyword added to FITS archive data to enable data verification.

  5. Arnaud- New release of XSPEC (v9.0) due out soon.

  6. Drake- Large volume of data requests, primarilly ftp, with WWW use increasing. Gamma-ray burst data summary.

  7. Corcoran- ROSAT archive running well.

  8. White- ASCA archive has a new excellent WWW access tool.

  9. Calvo- Development of meta-database of pointers to HEASARC data in early stages.

  10. Behnke- Described new upgrades to NSSDC NDADS system, including DLT jukebox and FDDI network upgrade.

  11. Riegler- MO& faces a factor of two reduction in 98-99. In two years another senior review will compare not only the mission reviewed recently, but also the grants programs, LTSA, and the HEASARC. 25% of MO& is spent on mission planning and operations; he challenges us to improve this by increased automation and efficiency.

Highlights of the HEASARC

As user groups often focus on the problems encountered over the past year, we wish to balance the impression, by recognizing the successes. We list those parts of the HEASARC which we especially wish to recognize for excellent achievement.

  1. The entire WWW-interface to the HEASARC is impressive, and provides an excellent example to the community.
  2. The SkyView system and its WWW access tool.
  3. The improvement in on-line accessibility to HEASARC holdings.
  4. The great progress on acquiring and restoring datasets.
  5. The ASCA archive opened on-time and with no important problems.
  6. The HEASARC staff have been highly responsive to user questions.
  7. The FITS support work for the community.
  8. The international scope and cooperation achieved is a sign of the respect and quality work done by the HEASARC.

Business for the Next Meeting

The next meeting of the HUG will be planned for early November. The users prefer a Friday to have lower cost air fare.

Two members will rotate off the HUG, Martin Elvis and Kevin Hurley. Replacements will be appointed soon.

We request a presentation on the data compression standards in use at the HEASARC at the next meeting. We also request a brief report from the NSSDC on the data protection and multiple copies policies of the HEASARC data held by the NSSDC.

HEASARC user group members can explode messages to the HUG by addressing them to `'.

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