Dataset Formats

For any HST observation, the STScI data processing pipeline produces not just one data file, but an entire set of files, known as a dataset. All files for a particular observation have the same root name. The type of data in each file is identified by its extension. The raw (uncalibrated) and calibrated files are available for each dataset, as are files describing the data quality and calibration process.

Science data are stored in the HST Archive in FITS format. To work with HST data within the Image Reduction and Analysis Facility (IRAF), one can use the Space Telescope Science Analysis System (STSDAS). Users interested in displaying HST images can do so by using various FITS readers. For example SAOimage (ds9), which can be retrieved via anonymous FTP from sao-ftp.harvard.edu in the directory /pub/rd/ds9, runs on various systems.

Specific details about the format and content of science datasets are described in the HST Data Handbook.

Dataset Sizes

We list here typical file and dataset sizes for calibrated data for each HST instrument.

Instrument	Mode	Dataset Size
ACS/WFC	singleton average association with 2 members associtaion with 4 members	428 MB 629 MB 1017 MB
ACS/HRC	singleton association with 2 members associtaion with 4 members	35 MB 50 MB 81 MB
ACS/SBC	singleton association with 2 members association with 3 members	40 MB 60 MB 72 MB
FOC	Normal 512 x 512 Zoom 1024 x 512	~ 4 MB 8-10 MB
FOS	Normal Rapid readout	< 500 KB > 10 MB
GHRS	Normal Rapid readout	< 500 KB > 10 MB
HSP	Normal Occasional	~ 500 KB > 1 GB
NICMOS	CAL file IMA file	~ 1 MB ~ 0.75 MB/readout
STIS	CCD/MAMA image CCD/MAMA spectrum	> 10 MB > 14 MB
WFPC, WFPC2	Normal (full mode) Area mode	26 MB 7 MB