The SOHO Solar Oscillations Investigation on the Web
Karen Tian, Philip H. Scherrer, & Richard S. Bogart
Center for Space Science & Astrophysics and
Dept. of Computer Science,
Stanford Univerity
Table of contents
Abstract
The Solar Oscillations Investigation (SOI) is an international project
to study the Sun's interior using data from the Michelson Doppler Imager
on the Solar and Heliospheric Observatory and the newly developing
techniques of the field of helioseismology. We have committed to
using the World Wide Web not only to provide information and public
data, but as an active tool for defining science objectives, planning
and conducting the mission operations and attendant data processing,
as well as distribution of data to team members. SOI is organized into
a number of Science Teams with responsibility for various aspects of
the mission. As the team members are widely dispersed geographically,
the Web will be used to provide them with operational views into all
aspects of the data flow from observations through the production of
organized calibrated datasets. The same tools will be available to
team members and guest investigators conducting individual science
investigations.
The Solar Oscillations Investigation (SOI) is an international cooperative
effort to study the interior of the Sun using the techniques of
helioseismology and related analysis applied to data from the
Michelson Doppler Imager (MDI) on the Solar and Heliospheric Observatory (SOHO).
The SOHO mission, a joint ESA-NASA effort, is scheduled for launch 31 Oct. 1995,
with arrival on station in a halo orbit about the Earth-Sun
L1 Lagrangian point in early 1996. MDI is capable of generating
and transmitting two high-resolution images of the Sun per minute, in
combinations of Doppler signal, filtergram or whitelight intensity, or
Zeeman signal, and will remain active for the duration of the mission, at
least two and up to six or more years. The total data archive expected
to be accumulated is on the order of 3 Terabytes per year of operation.
SOI has adopted the tools of
the World Wide Web as the primary network communications service to
provide timely information of interest to team members, other scientists,
and the public. The primary functions of the Web services are to provide:
In this paper we discuss and illustrate the various
services, both extant and planned, of the SOI Web. The paper is itself
accesible on the World Wide Web at the URL
http://rick.stanford.edu/pubs/Strasbourg_2.html.
On the Web the hyperlinks
can of course be followed to illustrate the features discussed.
General Information
As with most World Wide Web servers, the main page and registered entry point,
at URL http://soi.stanford.edu/,
provides general information about the SOI and an index to major categories
of data services. This includes a brief introduction
About SOI,
information (including references to personal and institutional home pages)
about members of the
SOI Team,
information about forthcoming and past
Team Meetings and related scientific and technical conferences, and an
archive of SOI Newsletters (not yet on line). The main and general information
pages attempt to provide the usual complement of external hyperlinks to
related information services on the Web.
The current general information pages have been designed with the SOI
participants in mind, as a way of introducing the more useful technical
features we are constructing. We hope to significantly expand their
breadth, however, to include background and infomational materials suitable
to general browsers and especially students and educators. We are convinced
that with its ease of access and enormous potential audience, the Web can
provide the ideal medium for communicating the excitement and challenges
of this scientific endeavor to the public from whom we must draw both
support and future participation. If we can find support, we would like
to provide analysis tools and sample data for educational exercises. We
are currently exploring links with various educational organizations to
do so.
Quick-Look Data
The Web provides the ideal mechanism for distribution of quick-look data,
i.e. data that have not been definitively analyzed, but are made
available as soon as possible to the scientific community for purposes of
planning and conducting other observations. SOI has the potential to
provide full-disk magnetograms, white-light images, Dopplergrams, and
other more exotic diagnostics such as maps of integrated line-of-sight
velocity power on a very regular basis, without interruptions or variations
in quality. The potential users of such quick-look data include the SOI
team itself and other experiments on SOHO in planning and coordinating
observing campaigns, ground-based observatories in conducting both supporting
observations and their own programs, and solar and space-weather forecasters.
Quick-look data services have not yet been implemented. Several formats
are appropriate, depending on the nature of the data and the potential
applications: HTML-based text and tables, GIF and JPEG images, MPEG
movies, and binary (FITS and/or CDF) data for downloading. So far we have
only made provision for data of the last type to be furnished to the SOHO
Experiment Operations Facility, and this is outside the context of the Web.
Data Services
The enormous quantity and variety of data to be processed in the conduct
of the SOI has required the development and implementation of a fairly
sophisticated database system for tracking data and making them available
to both the processing pipeline and the users. This system, the Data
Storage and Distribution Service (DSDS) is being interfaced to the Web
through query services to provide data access through ASCII reports,
forms-based queries to the database catalog, and requests for export of
selected datasets to the user. Requested data will be exported either
by copying to scratch space on local disks or by copying to offline
media (primarily 8mm Exabyte tapes). Examples of
Data Catalog Query Forms
and
Data Catalog Query Results are available.
There are presently over 120 SOI Technical Notes documenting various facets
of the investigation, and they continue to be generated at the rate of roughly
20 per year. These notes have been aimed at internal use, although they do
include a number of preprints of scientific contributions.
So far the primary mode of distribution has
been on paper, and we have consequently tolerated a wide variety of formats,
whatever has suited the authors, including plain text, Rich Text Format,
FrameMaker, Word for Windows, TeX, PostScript, and HTML.
We are gradually putting as much of this
body of working information online through the Web as possible. A hypertext
Index of Technical Notes is available, referencing each online
document. Since the large majority of the tech notes are not in HTML format,
the index gives information about the format of each note, so the reader
can know whether appropriate tools exist to view the document. So far
only about 20% of the notes are actually online. We are in the process
of assembling as many as possible and providing translations into HTML in
suitable cases.
A number of man pages for the data processing and analysis software
have been converted to HTML format and placed online in the directory at URL
http://soi.stanford.edu/manpages/. This project is not yet
incorporated in the main SOI Web services; it needs to be
brought and kept up to date to be of use. Even more important, the individual
man pages need to be indexed and described in a software user's guide.
Web pages also provide a suitable medium for preparation and dissemination
of scientific papers, but we have only begun to experiment with this
possibility. A few of our contributions to the SOHO Workshop on
Helioseismology at Asilomar (obviously including this one) have been
prepared and will remain on the Web, but we do not yet have a formal
structure for organizing group publications outside that of the Technical
Notes. An obvious advantage to the Web is the incorporation of images,
but the lack of support in Web browsers for mathematical symbols and
typography is a significant drawback.
We use the World Wide Web not only to provide information and public
data, but as an active tool for defining science objectives,
planning and conducting the mission operations and attendant data
processing as well as distribution of data to team members.
SOI is organized into a number of Science Teams with responsibility for
various aspects of the mission. As the team members are
widely dispersed geographically, the Web will be used to
provide them with operational views into all aspects of the
data flow from observations through the production of
organized calibrated datasets. The same tools will be
available to team members and guest investigators
conducting individual science investigations.
The core scientific program of SOI is to be achieved through a set of
well-defined
Team Science Objectives. The activities of each of the
science teams are described in detail under each of a set of
Team Science pages. There is a page of
Guidelines
for establishing, planning, and conducting investigations.
We also provide a form for
Individual Investigation Proposals.