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