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Astronomical Data Analysis Software and Systems VII
ASP Conference Series, Vol. 145, 1998
R. Albrecht, R. N. Hook and H. A. Bushouse, e
Ö Copyright 1998 Astronomical Society of the Pacific. All rights reserved.
ds.
New Developments in the FITSIO and Fv Software
Packages
W. Pence
NASA/GSFC, Code 662, Greenbelt, MD 20771, Email:
pence@tetra.gsfc.nasa.gov
Abstract. This paper describes recent improvements to the FITSIO
subroutine library and the fv FITS file viewer and editor, both of which
were initially described at previous ADASS conferences.
1. Introduction
The FITSIO subroutine library for reading and writing FITS format files was last
described in the ADASS IV conference proceedings. Since then there have been
many significant improvements that are outlined in this paper. Similarly, recent
improvements to the fv FITS file viewer and editor are described to update the
previous paper in the ADASS VI proceedings. Both packages are available from
the HEASARC Web page at http://heasarc.gsfc.nasa.gov/docs/HHP sw.html.
2. FITSIO/CFITSIO
Since the time of the last FITSIO update (Pence 1995) a new CFITSIO library
has been developed, written entirely in C. CFITSIO is easier for C programmers
to build and call than the previously available C wrapper routines built on
top of the fortran FITSIO library. Both the FITSIO and CFITSIO libraries
have now been optimized for maximum data I/O performance and can achieve
throughputs of order 5 -- 10 MB/s or more when reading or writing FITS files
on current generation workstations or PCs.
As originally developed, the FITSIO and CFITSIO libraries provided ex­
actly the same functionality to fortran and C applications programmers, re­
spectively. Recently, however, several new features have been added to CFIT­
SIO which are not available in the FITSIO library. It is quite time consuming to
maintain the independent FITSIO and CFITSIO libraries with exactly the same
functionality, so in the future it is likely that the FITSIO library will be frozen
in its current state and that new features will only be added to the CFITSIO
library. To make these new CFITSIO features easily available to fortran pro­
grammers, a new set of fortran wrapper routines for the CFITSIO library is
currently being tested. These wrappers will provide the exact same subroutine
calling sequence and functionality as currently provided by FITSIO, but will
actually call the corresponding routine in the CFITSIO library.
One of the important new features that is only available in the CFITSIO
library is the ability to read or write FITS files directly in computer memory as
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98 Pence
well as on disk. As a result of this, programs can now read FITS files piped in
via the `stdin' stream, or write them out to the `stdout' stream. This enables a
sequence of tasks to pipe the output FITS file from one task on to the input of
the next task entirely in memory. This eliminates the need to write then read
back temporary FITS files on magnetic disk and can greatly reduce the amount
of time spent doing data I/O in pipeline processing.
Another important new feature in CFITSIO is the ability to directly read
compressed FITS files that have been compressed with the gzip, PKZIP, or
Unix `compress' algorithms. This enables programs to directly read the com­
pressed FITS files that often exist in on­line data archives or are distributed on
CDROMs, without first having to uncompress the FITS file.
3. Fv FITS File Editor
The fv program for viewing and editing the contents of any FITS file has under­
gone many improvements since the original announcement (Pence, Xu & Brown
1997). Fv is written in Tcl/Tk and provides a graphical display of the header
keywords, tables, and images in the FITS file. The current release, V2.1, has
many spread­sheet type functions for sorting tables, inserting or deleting rows
or columns in a table, and recalculating the values in any column. Fv can dis­
play FITS images and make line plots of the values in table column(s) using an
integrated Tcl/Tk tool called POW. It supports interactive image analysis in­
cluding panning and zooming, and brightness and contrast manipulation. POW
also supports readout of image coordinates using the standard FITS World Co­
ordinate System keywords.
Fv currently runs on most Unix workstations, but by the time this article
is published, version 3.0 of fv should be available which will also run on IBM
and Macintosh personal computers. This will make fv more accessible to the
educational community and to the general public as a tool for easily viewing
and analyzing the growing database of recent astronomical discoveries that are
stored in FITS format.
Acknowledgments. The fv program has been principally developed by Jian­
jun Xu, based on preliminary work by Dr. Jim Ingham. The POW image dis­
play and plotting package has been developed by Dr. Laurence Brown. The
continuing development of fv and POW is supported by the High Energy Astro­
physics Science Archive Research Center (HEASARC) at the NASA Goddard
Space Flight Center and has been partially funded by a grant from the NASA
Astrophysics Data Program.
References
Pence, W. 1995, in ASP Conf. Ser., Vol. 77, Astronomical Data Analysis Soft­
ware and Systems IV, ed. R. A. Shaw, H. E. Payne & J. J. E. Hayes (San
Francisco: ASP), 245
Pence, W., Xu, J. & Brown, L. 1997, in ASP Conf. Ser., Vol. 125, Astronomical
Data Analysis Software and Systems VI, ed. Gareth Hunt & H. E. Payne
(San Francisco: ASP), 261