Evaluating such positive and negative aspects, we have reached a consensus that the reasoning for holding the privileged data use interval is now drastically reduced thanks to longevity of Yohkoh. Thus, with concurrence by ISAS, we here announce a new policy that all the Yohkoh data be immediately after acquisition. We hope the world science community in solar physics and physics will analyze Yohkoh data as actively as but more quickly before. Those who are not familiar with how to make use of the Yohkoh data, please contact:

• the Solar Data Analysis Center, NASA/GSFC ( yohkoh_sdac@solar.stanford.edu),

• the UK Yohkoh team at the Mullard Science Laboratory (J. Len Culhane), or

Takeo Kosugi, ISAS, representing Japanese participation

Loren Acton, Montana St. Univ., representing US participation

J. Len Culhane, MSSL, representing UK participation

Yohkoh is a mission of the Japanese Institute for Space and Astronautical Science (ISAS), conducted in collaborations with scientists from the US and the UK who are supported by NASA and the SERC. The primary database for Yohkoh is at ISAS, but the Solar Data Analysis Center (SDAC) at Goddard Space Flight Center (GSFC) is now prepared to provide public access to these data according to an agreement between ISAS and NASA. This service will start in October, 1993, on the occasion of the second anniversary of the start of the data acquisition by Yohkoh, following its successful launch from the Kagoshima Space Center. More recent Yohkoh data will be placed in the archives at the SDAC and NSSDC at an appropriate time; the second year of data will be available sometime in early spring 1994, and data for the third and subsequent years will be released in a continuous manner when the data becomes one year old, as long as Yohkoh remains in operation.

This release will include data from the Soft X-ray Telescope (SXT), the Hard X-ray Telescope (HXT), the Bragg Crystal Spectrometers (BCS), and the Wide-band Spectrometers (WBS). Existing data reduction software will also be released to ensure the effective use of the data; the maintenance and up-grading of this software will be undertaken by the Yohkoh investigators.

Both the Yohkoh Team and ISAS sincerely hope that the release of these data will enhance the scientific return from the satellite, by promoting research in the wider solar physics community. We also hope that the release will contribute to the promotion of public interest in science, especially of the younger generation, through use of the solar images in educational material and in the popular press.

Although these data are now open for general use, the Yohkoh Team continues to invite collaborations in their analysis. The Team is willing to assist all those who wish to use the data to help ensure its correct handling (which naturally requires certain degree of care).

When the data are requested, all necessary information and software for analysis will be supplied together with the data by the Solar Data Analysis Center.

For more detailed information on the Yohkoh data, or on scientific collaborations, or if you have any technical or software questions, please contact the GSFC Solar Data Analysis Center, or the Yohkoh Team, at

Yohkoh Data Requests (Western Hemisphere, Africa, Asia outside Japan):
Solar Data Analysis Center
Goddard Space Flight Center, Greenbelt, MD 20771, USA
email: yohkoh_sdac@solar.stanford.edu
fax: +1-301-286-8403

Yohkoh Data Requests (Europe):
Yohkoh Data Archive Centre
Mullard Space Science Laboratory, University College London
email: ydac@mssl.ucl.ac.uk
fax: +1-301-286-8403

Questions about Yohkoh Software:
SDAC, NASA, indicated above,
or Yohkoh Team, ISAS, indicated above, but with
email: SolarSoft development