### FITSLIST

Lists the FITS extension of an NDF

#### Description:

This application lists the FITS  header stored in an NDF  FITS extension. The list may either be reported directly to you, or written to a text file. The displayed list of headers can be augmented, if required, by the inclusion of FITS headers representing the current World Co-ordinate System defined by the WCS component in the NDF (see Parameter ENCODING).

#### Usage:

fitslist in [logfile]

#### Parameters:

If a non-null value is supplied, the NDF WCS component is used to generate a set of FITS headers describing the WCS, and these headers are added into the displayed list of headers (any WCS headers inherited from the FITS extension are first removed). The value supplied for ENCODING controls the FITS keywords that will be used to represent the WCS. The value supplied should be one of the encodings listed in the “World Co-ordinate Systems” section below. An error is reported if the WCS cannot be represented using the supplied encoding. A trailing minus sign appended to the end of the encoding indicates that only the WCS headers should be displayed (that is, the contents of the FITS extension are not displayed if the encoding ends with a minus sign). Also see the FULLWCS parameter. [!]
Only accessed if ENCODING is non-null. If TRUE then all co-ordinate frames in the WCS component are written out. Otherwise, only the current Frame is written out. [FALSE]
The NDF whose FITS extension is to be listed.
The name of the text file to store a list of the FITS extension. If it is null (!) the list of the FITS extension is reported directly to you. [!]

#### Examples:

fitslist saturn
The contents of the FITS extension in NDF saturn are reported to you.
fitslist saturn fullwcs encoding=fits-wcs
As above but it also lists the standard FITS world-co-ordinate headers derived from saturn’s WCS component, provided such information exists.
fitslist saturn fullwcs encoding=fits-wcs-
As the previous example except that it only lists the standard FITS world-co-ordinate headers derived from saturn’s WCS component. The headers in the FITS extension are not listed.
fitslist ngc205 logfile=ngcfits.lis
The contents of the FITS extension in NDF ngc205 are written to the text file ngcfits.lis.

#### Notes:

• If the NDF does not have a FITS extension the application will exit.

#### World Co-ordinate Systems

The ENCODING parameter can take any of the following values.
• "FITS-IRAF" –- This uses keywords CRVALi CRPIXi, CDi_j, and is the system commonly used by IRAF. It is described in the document “World Coordinate Systems Representations Within the FITS Format” by R.J. Hanisch and D.G. Wells, 1988, available by ftp from fits.cv.nrao.edu /fits/documents/wcs/wcs88.ps.Z.

• "FITS-WCS" –- This is the FITS standard WCS encoding scheme described in the paper “Representation of celestial coordinates in FITS”
(http://www.cv.nrao.edu/fits/documents/wcs/wcs.html).

It is very similar to "FITS-IRAF" but supports a wider range of projections and co-ordinate systems.

• "FITS-WCS(CD)" –- This is the same as "FITS-WCS" except that the scaling and rotation of the data array is described by CD matrix instead of a PC matrix with associated CDELT values.

• "FITS-PC" –- This uses keywords CRVALi, CDELTi, CRPIXi, PCiiijjj, etc, as in a previous (now superseded) draft of the above FITS world co-ordinate system paper by E.W. Greisen and M. Calabretta.

• "FITS-AIPS" –- This uses conventions described in the document “Non-linear Coordinate Systems in AIPS” by Eric W. Greisen (revised 9th September, 1994), available by ftp from fits.cv.nrao.edu /fits/documents/wcs/aips27.ps.Z. It is currently employed by the AIPS data analysis facility, so its use will facilitate data exchange with AIPS. This encoding uses CROTAi and CDELTi keywords to describe axis rotation and scaling.

• "FITS-AIPS++" –- This is an extension to "FITS-AIPS" that allows the use of a wider range of celestial projections, and is used by the AIPS++ project.

• "FITS-CLASS" –- This uses the conventions of the CLASS project. CLASS is a software package for reducing single-dish radio and sub-mm spectroscopic data. It supports double-sideband spectra.

• "DSS" –- This is the system used by the Digital Sky Survey, and uses keywords AMDXn, AMDYn, PLTRAH, etc.

• "Native" –- This is the native system used by the AST library (see SUN/210), and provides a loss-free method for transferring WCS information between AST-based application. It allows more complicated WCS information to be stored and retrieved than any of the other encodings.