Reading UIT Data

The UIT data files (see also Data Products) are written in straightfoward FITS formats. For an image file, the data are stored in the primary array. For a point-source photometry file, the data are stored as an ASCII table extension, with no primary array. The FITS header keywords describe the target, the processing history, and the characteristics of the data (see the "Guide to FITS Headers".

Please note that the UIT data files can be large. The complete set of files for a single observation requires about 3 Mb in gzip tar form and 28 Mb after decompression. A single calibrated, full-sized image requires over 8 Mb.

Various FITS readers written in IDL may be used to read the data files. These programs assume that the appropriate software and environment have been properly configured (see also UIT analysis software).

The MOUSSE software provides a number of UIT-specific programs for analysis and file I/O. The programs use an STSDAS-like file format, which requires the data and header to be split into two files. The program dfitsrd performs this simple conversion. For instance, dfitsrd,'nuv0342f.fits' generates two files, nuv0342.hhh (FITS header) and nuv0342.hhd (image data). Then the program strd may be used to read the files into IDL for display and analysis. For instance, strd, im, h, 'nuv0342f' reads the FITS header into the string array h and the image data into the floating-point two-dimensional array im.

The IUEDAC software also provides general FITS file reading tools, such as ifitsrd.