Figure: The display window of a program which allows correlating SSRT 1-D images with YOHKOH SXT maps and other images. Original PostScript figure (992kB).
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S. K. Konovalov, A. T. Altyntsev, V. V. Grechnev, and E. G. Lisysian
Institute of Solar-Terrestrial Physics, Lermontov St. 126,
Irkutsk, Russia 664033, E-mail: root@sitmis.irkutsk.su
A. Magun
Institute of Applied Physics, University of Bern,
Switzerland, 3012 Bern Sidlerstrasse 5, E-mail: magun@sun.iap.unibe.ch
The Siberian Solar Radio Telescope (SSRT) (Smolkov et al. 1986) is a large astronomical instrument. It is a cross-shaped interferometer consisting of 128×128 parabolic 2.5-meter antennas, equally spaced with a separation of 4.9m. The SSRT is located 220km from Irkutsk in a beautiful forest valley lying between the two chains of Sayan Mountains. This radio telescope is devoted to the study of solar activity in the microwave range (5.7GHz), where processes in the solar corona are visible across the entire solar disk. In 1992, fast observations were started for studying of the fine time structure of flare manifestations, such as spikes (Altyntsev et al. 1994). After introduction of a fast data acquisition system developed together with the Institute of Applied Physics (Bern) (Altyntsev et al. 1996), the SSRT can record processes as short as 14ms with a spatial resolution of down to 15´´.
The response of the SSRT is formed in a specific way, unlike that of most other aperture synthesis telescopes. The orientation of the interferometer's beam depends on the receiving frequency, making it possible to scan the solar disk by tuning the receiver in a series of steps. By making this stepwise tuning quick enough, we obtain a series of one-dimensional images (scans) taken across the Sun. This method-frequency scanning-provides fast sampling in one direction. It is used in the fast observations at the SSRT. The Sun passing through the fan beam provides sampling in the other direction. This sampling, together with frequency scanning, is used for 2-dimensional mapping of the Sun. Two-D mode observations started in autumn, 1995, and have been providing images every day since spring, 1996.
Observations produce a large amount of data, which require special techniques for processing and previewing. To solve this problem, we had to develop our own special programs. Considering the advantages lent by IDL, such as efficiency, easy coding, powerful graphics, and wide acceptance among astronomers, we have chosen this language. As a result, a set of IDL programs was developed to provide these capabilities:
Figure: The display window of a program which allows correlating SSRT
1-D images with YOHKOH SXT maps and other images.
Original PostScript figure (992kB).
To program more effectively, we have been trying to follow some guidelines:
Our widget-based programs are complex: a typical size ranges from 10 to 50kB. Each program consists of three to six routines and uses some dozens of local variables having different types and dimensions. Because it is unlikely that a user would run two or more copies of such a program simultaneously, most of them exchange variables by means of common blocks. These variables are collected into structures. When the program is terminated, and the respective widget dies, the memory is freed by setting all these variables into scalar values.
IDL does not provide for retaining the scaling in graphics windows; therefore, when working with a few windows, one has to save the state of the system variables !X, !Y, !Z, !MAP for all the graphics windows being in use, and restore them when the cursor is placed onto a particular window.
Besides completely widget-based programs, we have also developed a hybrid program using both widgets and conventional graphics windows. This approach makes it possible to use the IDL library routines (such as PROFILES, ZOOM, etc.) in a straightforward way, and expedites program development.
All the programs can be run under IDL 3.0.1 or later versions. We welcome any interest and cooperation.
This work was supported by the grants International Science Foundation (ISF) RLD000 and RLD300, ESO C&EE Programme A-03-049 and A-05-013, Swiss National Science Foundation 20 29871.90, and INTAS (INTAS-94-4625). Our special thanks to ISF for supporting our participation at this conference.
Altyntsev, A. T., et al. 1994, A&A, 287, 256
Altyntsev, A. T., et al. 1996, Solar Physics, 168, 145
Konovalov, S. K., Altyntsev, A. T., Grechnev, V. V., Lisysian, E. G., Rudenko, G. V., & Magun, A. 1997, this volume
Smolkov, G. Ya., Pistolkors, A. A., Treskov, T. A., Krissinel, B. B., & Putilov, V. A. 1986, Ap&SS, 119, 1
Next: Java: The Application and Data Distribution Vector for Astronomy
Previous: ETOOLS: Tools for Photon Event Data
Up: Science Software Applications
Table of Contents - Index - PS reprint - PDF reprint