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Astronomical Data Analysis Software and Systems VI
ASP Conference Series, Vol. 125, 1997
Editors: Gareth Hunt and H. E. Payne
S. K. Konovalov, A. T. Altyntsev, V. V. Grechnev, E. G. Lisysian,
and G. V. Rudenko
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
Abstract:
We process and analyze data provided by the SSRT interferometer
using IDL. Thanks to the well-known capabilities of IDL, this
has expedited our research.
Special requirements, convenience, and efficiency led us to the creation
of an expanding library of IDL routines and programs, described herein.
We have been processing and analyzing data provided by the
Siberian Solar Radio Telescope (SSRT) (Smolkov et al. 1986). Much
of these data required development of special techniques for
processing and previewing. Using the well-known capabilities of IDL,
we were able to speed up our research. However, a variety of routines had to
be developed due to the specific needs of our research and the features of our
instrument, as well as our desire to make processing still
more convenient and efficient. Having started this work in collaboration
with the Institute of Applied Physics (Bern), we continued it in Irkutsk.
Coming up with our own IDL installation
allowed us to expedite our work. As a result,
a whole set of routines and programs supporting our programming has emerged
(Konovalov et al. 1997). This set contains special routines for our use, as
well as routines which could be of common interest. This library is being
currently expanded.
In response to inherently specific features of our instrument, the SSRT,
and to our research needs and preferences,
we have developed, supplemented, and corrected
some routines from the standard IDL library.
Since our IDL library contains more than 100 routines and functions, we can
present here only an overview of these routines, classifying them by
category, and briefly describing their capabilities. The routines can
be used on UNIX and MS Windows platforms, and all can be run under
IDL 3.0.1 or later versions.
These routines and functions were written for specific needs,
but could be generally useful:
- String-type variables manipulation:
We have added
functions which allow
(i) finding a given substring in a string,
(ii) replacing it with a given model of arbitrary length, and
(iii) splitting a string containing any
delimiter (e.g., whitespace) into substrings.
- Files and file names manipulation:
These routines provide:
(i) conversion of text files between UNIX and MS Windows;
(ii) adding an End-Of-File marker;
(iii) extracting a short file name, extension, file name without
extension, and directory name from the full path name;
(iv) automatically recognizing the type of some graphics files (GIF, TIFF,
BMP, or FITS);
(v) creating a new file name, given a wildcarded pattern;
(vi) an interactive tool for deleting a file, etc.
- Mathematical functions:
We have developed routines for rapidly evaluating some
often-required functions:
(i) SIGN and SINC (sin x/x);
(ii) recognizing even numbers; and
(iii) calculating the Gaussian function.
Furthermore, some operations for array manipulation have
been implemented:
(i) conversion of 1-D subscripts into 2-D;
(ii) extracting subarrays; and
(iii) searching for coinciding elements in different arrays.
- Graphics windows manipulation:
We have developed routines expanding the standard IDL tools with the
following capabilities:
(i) bringing all existing graphics windows to the front;
(ii) deleting all existing graphics windows;
(iii) displaying current cursor coordinates within a selected graphics window;
(iv) saving and restoring scaling of the axes in a given window; and
(v) converting a cursor into another shape.
- Plotting routines:
We have developed the routines which:
(i) plot a graph versus time expressed in hours, minutes, and seconds;
(ii) plot a graph of a fragmented array;
(iii) plot a straight line of a given slope crossing a given point;
(iv) plot a given arc or circle;
(v) overplot a triangle-shaped marker onto a plot or image;
(vi) display an array in the brightness representation enclosed by axes;
and
(vii) provide a box-shaped cursor for widget-based programs, etc.
- Curve analysis:
The developed routines allow
(i) finding (and, if needed, marking on the plot) local extremes;
(ii) selecting a local peak;
(iii) calculating its width;
(iv) finding the circle passing through three given points;
and (v) finding a line bounding a given fast-oscillating curve (similar to the detection of a radio signal).
- Graphics file manipulation and image processing:
We use FITS files, so we have routines to handle the
headers (searching for a keyword and returning the corresponding value,
extracting of time and date from the header, etc.). We
can automatically recognize the type of some graphics files (GIF, TIFF, BMP,
or FITS) and display them on the screen. Routines were
developed to interactively measure the coordinates of the solar
disk's center and radius, and to save the image contained in
a graphics file into a FITS file. There is also a routine converting a plot
obtained from an image into a digital array, which can be saved for further
processing.
- Viewers:
Some viewers have been developed for the SSRT data, as well as for the
standard format graphics or digital files. There is an
interactive array viewer
which allows looking at data in various
representation (wire-mesh surface, shaded surface, halftone image, contour,
and their combinations), measuring profiles in two
directions, and reading pixel values. Contour levels can be selected
interactively. There is also a viewer for text files or string-type arrays
entered on the command line (similar to XDISPLAYFILE).
- Date and time formats and conversion:
A few routines and functions have been developed which
are used in reading data records, in calculations, and in
displaying date and time in a suitable form.
- Astronomical calculations:
Our routines:
(i) compute an hour angle, a declination, and a radius of the Sun;
(ii) calculate the heliographic, Carrington's, and plane coordinates, and
perform transformation between them;
(iii) compute the time interval between two events given in different
calendar formats;
(iv) transform the coordinates on the Sun according to differential rotation; and
(v) rotate a flat image of the Sun around the polar axis.
- Service widgets:
They are used for inputting a date and time, a brief text, or
coordinates. There are widgets for issuing a message, for obtaining an
answer to a question, and for selection of one item from the list, etc.
- Other:
The following routines we have not classified:
(i) conversion of a bit-serial array into a byte array;
(ii) creation of a new system variable !UC containing universal
constants;
(iii) selection and preparing of the graphics device required for the
next output (including setting of sizes, thickness, color, etc.), and
closing them; and
(iv) deallocation of all possible file units (convenient for debugging.)
These routines are oriented to SSRT data processing.
- SSRT: instrumentation, data processing:
A range of routines is used to calculate the parameters of the
SSRT beam and response as well as astrometric values; to read and convert
the information contained in the original records; to execute some actions
with original files; to perform data processing; and to
simulate instrumental characteristics of the SSRT and its response.
- Special routines:
We have also some routines completely for our own convenience, such as
converting ASCII codes from Roman into Russian, etc.
We have modified the routine CONGRID to transform small arrays
correctly. We have also supplemented the routine IMAGE_CONT with
various keywords, and edited it to display small arrays correctly. The
routine READ_BMP has been enhanced to handle monochrome images.
We welcome any interest and cooperation.
Acknowledgments:
We are grateful to Drs. B. Kliem (AIP, Germany),
Yu. M. Rosenraukh, T. A. Treskov, S. V. Lesovoi, V. G. Miller,
A. V. Bulatov, and B. I. Lubyshev (ISTP, Russia) for the helpful
discussion and the assistance in providing us with the data.
This work was supported by 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.
References:
Smolkov, G. Ya., Pistolkors, A. A., Treskov, T. A., Krissinel, B. B., & Putilov, V. A. 1986, Ap&SS, 119, 1
Konovalov, S. K., Altyntsev, A. T., Grechnev, V. V., Lisysian, E. G.,
& Magun, A. 1997, this volume
© Copyright 1997
Astronomical Society of the Pacific,
390 Ashton Avenue, San Francisco, California 94112, USA
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