Java Library for access to FITS files

The current Java Class Library for access to FITS files was designed for the VLT Data Flow System pipeline subsystem. This has meant that certain features have been included at this moment while others first later may be added. Some of the features included are:

• all types of headers are decoded,
• header are available even after the file is closed,
• DataInput streams can be used for initiation,
• in place modification of headers is possible.

The library has many limitations at this moment. The most important are listed below:

• RandomGroup data are not decoded
• Array and heap convention are not implemented for Binary table
• Data in ASCII table are decoded using the default Java formats and not as specified F77 conventions. This is okay in most cases but if floating point columns use an implicit decimal point or spaces should be interpreted as zeros, the data will be wrong.
• Limited support of writing FITS files (not including table data).
• Access to data is not yet optimized.
• WCS routines have not been well tested.

The current version (0.94) of the library is available in several forms:

• jar file compiled on Linux with JDK 1.5,
• source code under the GNU General Public License version 2
• documentation as generated by Javadoc.

The library has been tested on Linux SuSe 9.3 with JDK 1.5. As the code has not been optimized, data access is slow e.g. on a 160 MHz machine and no JIT, 32-bit real images are read at 50k values/sec, 16-bit integer images at 80k values/sec while table data are read at 10k values/sec. FITS keywords are decoded at a rate of 2-3k keywords/sec depending significantly on their types.

Two simple test programs are available both to test the performance and to show how to use the library. They are:

• TestFits.java which reads all extensions in a FITS file, lists their keywords and computes the average and standard deviation.
• ListFits.java which reads FITS headers and prints the values of a list of keywords given on the command line.
• CreateFits.java which shows how one can create data matrices as 1-D arrays and save them in a FITS file.

Currently, the two first test programs are members of the org.eso.fits package so they have to be executed as e.g. java org.eso.fits.TestFits file.

Note: The class library is currently in a preliminary alpha state and may be modified without warning.

Warning: The class library is provided as-is without any warranty. It is NOT an official produce of ESO and is currently maintained by myself at a best effort basis.