D1. IDL-based database on active regions

Dale Gary (New Jersey Institute of Technology), Victor V. Grechnev, Ludmila Shabarova (Institute of Solar-Terrestrial Physics SD RAS, Irkutsk, Russia), Angelos Vourlidas (SOHO LASCO Group), Masanori Nishio (Department of physics, Kagoshima University, Japan)

Researchers of solar activity often need to access solar active region data. Source of such information include the Solar Geophysical Data bulletin and other periodical publications. Searching the printed publications requires substantial time and effort. Although it is possible to obtain these data using the Internet, some limitations remain.

A convenient alternative would be an ``illustrated desk book on active regions'' in a form of a database placed in researcher's computer and equipped with a means of searching for desired information as well as printing or saving it in a suitable form. Such a ``desk book'' can be accessed quickly, allows data selection for information of interest, and can be easily supplemented and extended.

There are many common database file formats from which to choose, but may be limited to particular platforms or be unfamiliar to a wide community of researchers. We have chosen a widely used, platform independent software environment called Interactive Data Language (IDL), in which the SAVE/RESTORE feature is used to place data into a machine-independent format (XDR). The extensively used IDL programming language ensures complete compatibility with various platforms (MS Windows, Macintosh, several versions of UNIX, and VMS). We have initially created an IDL-based database on daily active region data from 1992 July 1 to 1994 December 31. The database file in its XDR format has a volume of 1 Mbyte.

The database is still more informative and hence especially valuable when used together with a daily set of radio maps for the same period, produced in total intensity and circular polarization by the Japanese Nobeyama Radioheliograph at 17 GHz (the radio images in FITS format reside on three compact disks). In this case, a researcher can easily access the database and at the same time view the microwave images which provide a visual indication of the location of the active region and further information about coronal magnetic fields.

The database is constructed as a multi-level IDL structure arranged into a regular array, each element of which corresponds to a single day. The record for each day contains: (1) a common field with data relevant to the entire visible disk of the Sun and (2) an array of fields for each active region (space limited to 10 active regions per day). Such a structure ensures that each element of the database can be accessed in a logical and flexible manner.

The common field for each day entry contains: a) observational date and time; b) angles of the Sun's orientation and its optical radius; c) number of active regions observable on the disk; d) peak radio brightness temperature of the visible disk at 17 GHz in intensity and polarization with the corresponding coordinates.

The array of structure fields for the active regions visible on each date contain: a) NOAA number; b) geocentric coordinates (offsets in arcsec from disk center) and heliographic coordinates (longitude and latitude in degrees relative to the solar equator and meridian); c) magnetic type ($\alpha$, $\beta$, $\gamma$, $\delta$); d) area; e) Carrington longitude; f) characteristics of the leader and follower sunspots: coordinates, 17 GHz radio brightness temperature in intensity and polarization, magnetic field according to data of Mount Wilson.

The database is accessed through a control program has a graphical interface for maximum efficiency and convenience. The control program implements various search and selection modes and also allows viewing of the Nobeyama 17 GHz radio maps in intensity and circular polarization when the compact disks containing those data are available. Screendumps are available in a graphical file (GIF format) or in a separate graphics window. Data matching a given criterion can be selected by means of simple actions: menu selections and entering values of interest. It is possible to save data relevant to a selected date or an active region into a text file.

The user has access to the following information:

• position of active regions and their NOAA numbers on the visible disk of the Sun for a selected date together with the heliographical grid;

• data for the current date and data for a selected active region (selection is carried out by means of mouse pointer);

• solar coordinates corresponding to the mouse pointer and (if radio map is available) brightness temperature;

• variations of area, latitude, brightness temperature, magnetic field for the leader and the follower sunspots of a selected active region during its passage across the solar disk, which can be plotted on the screen (and saved into a file);

• possibility of viewing radio maps (if the FITS files containing data of the Nobeyama Radioheliograph are available); zoom of a selected part of the image is possible.

The program has means to view recorded text files and headers of FITS files. A possibility is reserved to add data into the database file and to correct recorded data. The program code has been checked under MS Windows 95 and UNIX with IDL versions since 3.0.1 to 5.0.2.

Further development of the program is being planned which provides for overlay of the other radio data, including SSRT data on the solar disk as well as other capabilities.

This work was supported by SCOSTEP-96 grant.