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Frequently Asked Questions

* DATA REQUESTS

1. Why does it take so long to download the UIT files?

2. How can I tell which files are fully calibrated?

* READING FILES

3. How do I read the UIT data files?

1. Why does it take so long to download the UIT files?

The combined files for each observation are fairly large, about 28 Mb compressed, 51 Mb uncompressed. If you need only one file for a given observation, such as the fully calibrated and geometrically corrected ("G") file, you may wish to obtain it from the anonymous ftp site (see Obtaining UIT Data).

2. How can I tell which files are fully calibrated?

The easiest way is by the file name. The raw image (digitized densitometer output) filenames end in D, e.g. fuv0345d.fits. The linearized, flat fielded image filenames end in E (no good astrometry solution) and F (good astrometry solution). The fully calibrated, geometrically corrected image filenames end in G.

3. How do I read the UIT data files?

The image files are in FITS format, with the data stored in the primary arrays. The point-source photometry data are stored in ASCII table extensions, with no primary array. These simple FITS formats should be readable by a variety of FITS readers. See Reading UIT Data for more information.