Data Archive of the YDAC

The Yohkoh Data Archive Centre holds a complete set of data from all the Yohkoh instruments, and also all data from the TRACE mission. You may obtain Yohkoh data through the YDAC Data Request web page.

Specify the dates and times required, together with which instruments files you need; the data will be prepared and you will be informed by e-mail when they are available to be copied by anonymous ftp. If you have a large or complex data request, you may prefer you to visit the YDAC in order to gather the data yourself.

Please note that all Yohkoh data requests are subject to the YDAC Data Policy - if you are collaborating with someone, please tell us.

YDAC Data Policy


The YDAC follows the agreed data policy of the Yohkoh Team. All YDAC users are allowed full access to any Yohkoh data more than twelve months old; this data is in the public domain. Those researchers who have links with the Yohkoh Team on specific projects can access more recent data if needed.

Everyone using Yohkoh data provided by the YDAC is encouraged to register their interest in analysis projects through the Team Bulletin Board; this is the way Yohkoh Team members keep in touch. If necessary, the YDAC can help users establish collaborations with appropriate members of the Yohkoh Team.


All TRACE are in the public domain.

User Access to the YDAC

Users who wish to analyse Yohkoh data can gain access to the YDAC through the Internet (IP Address For security reasons, we prefer all users to have their own accounts; accounts will be allocated to approved users on request after the completion of a simple form. A PostScript Version of the form is available.

Researchers in Europe who would like to have access to Yohkoh data that are in the public domain will probably prefer to contact this data centre, the YDAC (e-mail address:
Anyone within the United States should contact the Solar Data Analysis Center, the SDAC (e-mail address: