It is a matter of common knoledge, that solar magnetic fields and, in particular, magnetic fields of sunspots, play important role in many solar events. In Pulkovo observatory the long-term data set of daily observations of magnetic fields of solar sunspots was accumulated, which contains great potential for further researches in solar physics.

On the basis of this observations the project on creation database of sunspot magnetic fields database has been proposed by Pulkovo researchers led by G.F. Vyalshin . In 1998 the project was supported by the grant of RFBR 98-07-90372.

The basis of the database is array of values of maximal strengths and polarities of sunspot magnetic fields, measured by Zeeman splitting Fe lines (wavelength 6173 angstroms). An overwhelming part of these measurements were made by G.F. Vyalshin, who was a founder and, before his death in April 1999, a leader of the project.

Depending on structure of the presented information, the data in the base are arranged in separate sections, First section contains data of magnetic fields measurements of each sunspot. The files of the section have standard format (ASCII) with strictly determined column structure and contain numerical data of more than 24 thousand measurements, made during 2202 observational days in period since August 2 1957 till September 25 1997. Every file contains the data for one separate year, to which correspond the digits in the filename. Second section includes files containing sum data about magnetic fields for every observational day. The description of structure of these files is presented here. Data from these two sections are also available as zip-archives fdata.zip [115K] and days.zip [41K].

Third section contains 2200 scanned maps of the Sun (graphic files in GIF-format), representing sunspots drawings or photos and values of magnetic field strengths measured for them in definite day. The date, corresponding to year, month and day of observation, is refered in the name of the graphic file. Unfortunately, not all drawings have a good quality, though it is quite enough for identification of sunspots with their numbers and magnetic field values.

Two ways of access to the database are proposed. The first way is direct viewing of the data files with usual hypertext HTML-interface. The second one, based on CGI-script, gives advantage of using interactive search mechanism, which permits to make selection of magnetic field data by different criteria set by user. Here it is possible to set start and end dates of required data subrange, as well as range of strengths and polarities of sunspot magnetic field. Moreover, such information can be obtained both for each spot and as sum daily values. Therefore, some capabilities, usually available only in relational databases, are realized. It considerably increases efficiency of extraction and further usage of the database information.

The CD-version of Pulkovo database of sunspot magnetic fields on CD-ROM disks is also available. Therefore, all interested users can receive by mail this version on standard CD-ROM-disk. For this purpose it is necessary to send the order for Eugen Miletsky to the address: 196140. St.-Petersburg, Pulkovkoe shosse, 65/1, Pulkovo observatory, or by e-mail: milet@gao.spb.ru