If a coordinate system with the same Domain (name) already exists it will be overwritten, and a warning message issued.
AST files for use by this program will normally be those written by the ASTEXP program, and may either be standard ones designed for use with a particular instrument, or prepared by the user.
It is intended that this file should be one written by the ASTEXP application when a successful registration is made, and the user need not be aware of its internal structure. The files are readable text however, and can in principle be written by other applications or doctored by hand, if this is done with care, and with knowledge of AST objects (SUN/210). The format of the file is explained in the Notes section.
It will normally not be necessary to supply this keyword, since it can be given instead within the AST file. If it is supplied however, it overrides any value given there. [!]
"then it indicates, for each image, what its index number is. Thus if only one image is given in the IN list, and the value of INDICES is , then the frameset with the identifier
"will be chosen. If set null (!) the images will be considered in the order 1,2,3,…which will be appropriate unless the images are being presented in a different order from that in which they were presented to ASTEXP when generating the AST file. [!]
If the logging system has been initialised using CCDSETUP, then the value specified there will be
used. Otherwise, the default is
TERMINAL – Send output to the terminal only
LOGFILE – Send output to the logfile only (see the LOGFILE parameter)
BOTH – Send output to both the terminal and the logfile
NEITHER – Produce no output at all
If the logging system has been initialised using CCDSETUP then the value specified there
will be used. Otherwise, the default is
"to all the images in the current directory with names beginning
". The file
"has previously been written using ASTEXP with the parameter ASTFILE=camera.ast. A new frame with a Domain called
"is added to the WCS component of each image.
"instrum.ast obs1 indices=[3,4]
", writing the ID of each to the terminal only.
The AST file consists of the following, in order:
frameset 1 modifiers
frameset 2 modifiers
(end of file)
Characters after a
’ character are normally ignored. The constituent parts are composed as
A single blank line, which may contain spaces but no comments.
The framesets are written in AST native format, as explained in SUN/210.
Each frameset has an ID, and contains two frames (a Base frame and a Current frame) and a mapping
between them. The domains of all the Base frames should normally be the same, and likewise
for all the Current frames. For the images to which the file will be applied by ASTIMP,
their WCS components should contain frames in the same domain as the AST file
The ID of each frameset is used to determine, for each image, which of the framesets in the file should be applied to it. This ID is a string which can assume one of the following forms:
"FITSID KEY VALUE
" — This will match an image if the first FITS header card with the keyword
KEY has the value VALUE. If the value is of type CHARACTER it must be in single quotes. KEY
may be compound (of the form keyword1.keyword2 etc) to permit reading of hierarchical
" — This associates a frameset with an integer N. Usually N will take the values 1,2,3,... for
the framesets in the file. Typically the N
’th image in a list will match the one with an ID of
" — This will match an image if the Set Index attribute iin its CCDPACK Set header is equal to
the integer N.
USE keyword arguments
Currently the only modifier defined is FITSROT, which defines the name of a FITS header which specifies how many degrees to rotate the image before use. This rotation is carried out after the mapping defined by the frameset itself.
Global modifiers affect all images processed with the AST file. Frameset modifiers affect only those images which correspond to their frameset.
Rigorous error checking of the AST file is not performed, so that unhelpful modifications to the WCS components of the target images may occur if it is not in accordance with these requirements.
"value is the value assigned on the last run of the application. If the application has not been run then the
"defaults, as shown in the parameter help, apply.
Retaining parameter values has the advantage of allowing you to define the default behaviour of the application but does mean that additional care needs to be taken when re-using the application after a break of sometime. The intrinsic default behaviour of the application may be restored by using the RESET keyword on the command line.
Certain parameters (LOGTO, LOGFILE and NDFNAMES) have global values. These global values will always take precedence, except when an assignment is made on the command line. Global values may be set and reset using the CCDSETUP and CCDCLEAR commands.