A V A R I A B L E S T A R S A N A L Y S I S C O M P U T E R P R O G R A M

A R C H I V E

(Letter to the Editor)

T I M O T H Y B A N K S

Physics Department, Victoria University of Wellington, New Zealand

and

F R A N K J A N S E N

Computer Services Centre, Victoria University of Wellington, New Zealand

(Received 1 October, 1991)

Abstract. A library site for the storage of computer programs used in the analysis of variable stars has recently been set up. It is directly accessible across the computer networks, using standard procedures. Currently only a few programs for the analysis of the light curves of eclipsing binaries are stored at the site, although it is hoped that as the library becomes more well known, more investigators will deposit copies of their programs in it. This would result in a library where interested researchers could obtain the latest versions of analysis techniques from a comprehensive listing. Instructions for access to the site are also discussed.

The study of variable stars has led to the development of many different computer-based analysis techniques. As Banks and Budding (1991) pointed out for the sub-topic of eclipsing binaries, there are effectively only a handful of such techniques that a researcher need, and indeed should, be aware of. However, at present obtaining source code and documentation of these programs involves approaching those involved in the develop- ment of the appropriate technique. Usually tapes or diskettes have to be specially prepared for each request, and mailed out. Quite often this not inconsiderable effort is at least partially in vain, with the corruption of the files en route. A solution to this problem would be the adoption of a dedicated library site where up-to-date copies of the representative techniques could be stored, and extracted across the computer networks by those requesting that material themselves. Victoria University of Wellington (V.U.W.) has recently set up the beginnings of such a library, although at present it contains only a few synthetic light curve programs used in the analysis ofchromospheri- cally active stars, and eclipsing binaries (e.g., LIGHT (Hill, 1979), Mochnacki's GENSYN, and the Information Limit Optimisation Technique (e.g., Budding and Zeilik, 1987) source codes). It is hoped that the library will become more comprehensive as researchers choose to deposit copies of their codes, developing the site into a useful resource for the astronomical community, and a labour saving device for the authors of code.

The files are stored on V.U.W.'s Silicon Graphics parallel processor, and are avail-

Astrophysics and Space Science 190: 155-158, 1992. �9 1992 Kluwer Academic Publishers. Printed in Belgium.

156 T. B A N K S A N D F. J A N S E N

able by anonymous FTP (File Transfer Protocol), which allows the transfer/copy of files to and from a remote network site. Those interested in contributing to the library should contact one of the authors (T.B.) either by normal mail, or at the electronic mail address of bankst@kauri.vuw.ac.nz. Files can be sent on disks or tape, although it is possible to directly FTP files into the pub/astrophys/Upload directory. Files stored in the latter manner will be invisible to all remote users, preventing the copying of such just submitted files until their storage has been approved and the files placed in the public section of the library. Standard Copyright notices, specifying that general use and copying is allowed without charge as long as the Copyright notice is intact, should be included in the code. In no manner is V.U.W. laying claim to the code, but merely acting as a possible storage and distribution site. Nor does it aspire to be the only available method of distributing the codes. V.U.W. is not placing any charges for storage, the copying of files, or access to the site in any way.

Documentation for some techniques is copious, and so standard mail may have to be used for these instructions. With other methods the documentation may already be available in computer readable form, or be suitable for Optical Character Recognition scanning (at V.U.W.) into such a format. In any case, authors may prefer to distribute the documentation themselves so as to monitor the distribution of their code. The site should still be useful though, as the problems of corrupting code should be avoided, as well as the problems of placing the files into a suitable format and media for those requesting the code. A small file with the suitable address to contact, for instructions and help, could be placed with the code itself.

All the archives files have been compressed in size using the standard adaptive Lempel-Ziv algorithm, as indicated by the file extension .Z (e.g., manual.Z). Typically this technique can reduce a source code file's size by 50-60~o, enabling it to be transferred between computers more quickly. Ultimately compression will also allow more files to be stored within the library itself, which is naturally of finite size. Storage problems should not develop within the near future. Decompression routines are very common, and indeed standard features in the Unix and VMS operating systems.

Accessing the site itself is simple, and available to anyone on the 'Internet'. To begin, at your system prompt, enter:

ftp kauri .vuw, ac .nz

or, if your site fails to identify the library site:

ftp 130.195.11.3

A message to the effect that a connection is being attempted, and then achieved, should appear. On a Unix system you will be prompted to log in, while in VMS you will simply be advised of a successful connection, and the prompt f tp> will appear. In the former case enter anonymous as the username, while for VMS (the actual format depends on your host site's FTP handler and so may differ slightly) type

login anonymous

A VARIABLE STARS ANALYSIS C O M P U T E R PROGRAM ARCHIVE 157

In either case you will then be asked for your 'internet' (email) address as the password,

e.g.,

bankst@kauri.vuw.ac.nz

Once logged in used cd to change directories, and Is (or dir) to list a directory's contents. Firstly, you will need to move into the 'astrophys' directory, i.e., for a Unix system enter

cd pub/astrophys

or for some VMS systems enter:

set def "pub/astrophys"

This directory is built up of several more sub-directories, each containing the code and

documentation of a given technique. The file README.Z contains a listing of the files in the library, their purpose, and what system they ran on. Generally, only the input/

output needs to be altered for the codes to run on other machines. It is well worth copying this file back. Ensure that you are in binary transfer mode by entering

binary

and then get the file by

get README.Z

Messages will appear indicating that your command was successful, and eventually that

the transfer was complete. The contents of a file cannot be examined at the archive itself,

but rather the file must be copied back to your home system first. By using cd (set def),

get, and ls (dir) a researcher can retrieve whatever code they require. Once all files needed have been copied back to the home site, enter dose (disc for some VMS systems) and quit to close the connection and return to your system prompt. Decompress the files on a Unix system using the command:

nncompress file.Z

where file.Z is the name of the compressed file. Some Unix systems will use compress

in the place of uncompress, as the direction of compression will be automatically determined. On a VMS system the decompress command must be used, e.g.,

decompress matinv.for.1 matinv.for;2

where matinv.for;2 will be the decompressed version of matinv.for; 1. Note that on a VMS system, files that were stored in the library with a VMS style name (e.g.,

matinv.for; 1.Z) will lose the .Z during transfer. If you are copying such files back to a U N I X system, rename them by specifying a new name for your system by using get like

get matinv.for;1.Z matinv.for.Z

which will copy matinv.for; 1.Z to a file called matinv.for.Z, without the semi-colon

[58 T. BANKS AND F. JANSEN

which can cause problems in Unix file names. Further details about the decompression routines should be available in your local on-line help. With files originally from PCs, it is well worth checking the end of the files for a line created by some file editors. Delete this line, and compilation should proceed well.

To conclude, it is hoped that the variable stars community will make use of this resource, which is being freely offered by V.U.W., and help build up a comprehensive compilation of the currently available techniques. The adoption of a single site should result in less time being spent by developers distributing the code (who need only deposit one copy in the library itself), as well as a faster distribution of new and updated codes.

Acknowledgements

The authors would like to thank the researchers who have already contributed to this archive site, or who have expressed interest in it. We would also like to express our thanks to the IAU Secretariat for poster space at the General Assembly, Commission Five's Working Group, and Mr Steven West who kindly presented this paper at the conference for us, at short notice. Dr Edwin Budding also presented this topic for us at the subsequent Cordoba meeting, and has been a source of most helpful assistance.

References

Banks, T. and Budding, E.: 1991, The Observatory 111, 38. Budding, E. and Zeilik, M.: 1987, Astrophys. J. 319, 827. Hill, G.: 1979, Publ. Dominion Astrophys. Obs. 15, 297.