Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.gao.spb.ru/english/publ-s/viii-rfs/p139.pdf Дата изменения: Mon May 21 17:34:18 2007 Дата индексирования: Tue Oct 2 00:45:26 2012 Кодировка: Поисковые слова: ion drive

Instruments and Methods

139

Data browsing at Metsahovi Radio Observatory
Prisse Kononen, Ari Mujunen, and Jan Engelberg
Metsahovi Radio Observatory, Kirkkonummi, Finland There are several di erent types of non-astronomical, chronological data which are collected non-stop at Metsahovi Radio Observatory. The purpose of the data is to aid the observations and to help the maintenance and upgrading of the instruments. At present this kind of data is received from two Weather Stations, the Spectrum Analyzator, and the EFOS-9 hydrogen maser at Metsahovi. It is probable that in the future there will be more data from several kinds of sources that need to be collected. So far the main restriction in utilizing these data repositories has been the inconvenience, due to the absence of suitable programs to visualize and manipulate the collected "raw" data. The daily collected plain text data les consist of the lines including the UT timestamp and the numeric value of the parameters at the observation moment, and in some cases also the name of the parameter. The number of lines in one data le varies a lot being attributable to the observation frequency which is typically an observation per a time period of few minutes. The easiest method to study the collected data is to present it graphically, observing the time value in the x-axis and the observation values in the y-axis. One must be be able to determine several selective options to present the data. The most obvious and important options are the determination of the certain time period and the selection of the parameters. Also important features are the choice to draw the value lines of several parameters into the same graph and the possiblityto save the selected parameter values into a le for further data processing. Because all Metsahovi employees have the access to the WWW, a cgi-program written in the Perl programming language was regarded the most suitable choice. The characteristics in favour of the Perl language are its text data manipulation capabilities as well as its "glue-like" nature which enables the required combination of the system commands, the plotting program commands and the HTML-scripts in one single program. The choice for a plotting program in the the Linux computer environment of Metsahovi Radio Observatory was the Gnuplot plotting utilityon account of the easiness to apply the important time-axis with it. The rst allotment that is under construction is the presentation of the weather data. The rst version of the weather data presentation program is available at the site http: kurp.hut.fi local which limits the access only to the network computers of Metsahovi Radio Observatory. The programmed subroutines are made as general as possible so that they can be used directly to program the presentation of the efos9- and the spektr-data, too.