7.3: DEIMOS data storage format glossary

FITS

The Flexible Image Transport System. This is the IAU-endorsed standard scheme for astronomical data interchange. It is defined by a series of papers which have appeared in Astronomy and Astrophysics Supplement. It is not related to any particular implementation in code.

FITS Header

A list of keyword/value pairs which introduces a FITS file.

HDU

A FITS Header/Data Unit. This is the basic building block for FITS files. Multiple HDUs can be concatenated into a single file.

PHDU

A primary FITS Header/Data Unit. All FITS files must begin with a HDU that contains an image, even if that image is of zero size.

FITS Table

A FITS HDU which contains a table of information; e.g., a star catalog or event/history log.

FITS Grouping

A scheme for hierarchical grouping of FITS files using embedded tables was proposed in a document available as URL=http://adfwww.gsfc.nasa.gov/other/convert/group.html This document details a protocol by which FITS files can be associated with other FITS files. The protocol can be used to specify various relations, including one-to-one, one-to-many, and many-to-many relations. It can thus be used to transmit elements of relational databases. This scheme has been implemented and can be used to interconvert FITS and HDF.

HDF

NCSA's Hierarchical Data Format. Unlike FITS, this data format is defined by a particular implementation and subroutine library interface. The format is in wide use in the physical sciences, and NCSA provides a number of sophisticated data browsing tools.

NCSA

The National Center for Supercomputing Applications at the University of Illinois, Urbana-Champaign.

WCS

World Coordinate System. A WCS is used to convert from image pixel coordinates into real-world coordinates such as RA and Dec. The FITS community has been considering a draft proposal for documenting astronomical WCS scenarios.

RAID

Redundant Arrays of Inexpensive Disks. A technology which combines many separate, relatively slow and small disks into a device which appears to be a single, large, fast disk.

ATM

Asynchronous Transfer Mode. A high-bandwidth data transfer technology for networking. Initial implementations provide rates of 155 Mbits/s, but the vendors promise increases of more than a factor of ten.

IRAF

NOAO's Image Reduction and Analysis Facility. One of the most commonly used systems for processing astronomical data.

cl

The IRAF command language.

task

A basic element of IRAF data processing.

STScI

The Space Telescope Science Institute

HST

The Hubble Space Telescope

NICMOS

Near Infrared Camera Multi-Object Spectrograph. A second generation instrument for HST scheduled for launch in 1997.

STIS

Space Telescope Imaging Spectrograph. A second generation instrument for HST scheduled for launch in 1997.