This routine imports FITS information into the CCDPACK extension of a list of images. FITS information (probably provided by the instrument/telescope control systems) can be used to specify certain parameters which are required by CCDPACK to perform "automated" reductions. These might cover such items as the type of data (target, flatfield, bias frame etc.), the Analogue-to-Digital Conversion factor, the nominal readout noise, the position of any bias strips (over-scan regions) etc.

The import is controlled by a "table" which specifies how FITS keyword values should be interpreted. This allows the evaluation of functions containing many FITS keywords as well as the mapping of CCDPACK recognised character items to arbitrary strings.

IN = LITERAL (Read)

LOGFILE = FILENAME (Read)

LOGTO = LITERAL (Read)

NAMELIST = LITERAL (Read)

TABLE = LITERAL (Read)

import in=’$\ast$’ table=$CCDPACK_DIR/WHTSKY.DAT

This example shows all the images in the current directory being processed using the import control table $CCDPACK_DIR/WHTSKY.DAT.

PRESENT.

The import control (translation) table is an ordinary text file which contains instructions on how to transfer FITS information from the FITS extension to the CCDPACK extension of an image. "Translation" is required since no standard interpretation of FITS keywords can be made and because the items which may be required can be compounds of single FITS keyword values.

In its most simple format a FITS control table is just a series of lines which contain the names of CCDPACK extension items and the names of the FITS keywords to which they map.

If the HDS type of the destination Extension-item is known this may be included.

Normally this is inferred. This is the format used by the KAPPA application FITSIMP (as of KAPPA version 0.8-6U). Extension items are the names of CCDPACK items (such as FTYPE, FILTER etc.). These may be heirarchical, e.g. TIMES.DARK. Note that they exclude the "NDF_NAME.MORE.CCDPACK." part of the extension path name.

To allow functions of FITS-keywords to be possible a second "declarative" form of statement is necessary.

So for instance if you wanted to derive an exposure time for an observation which was given in milliseconds and which you wanted to convert into seconds you would use this sequence of commands:

The "_INTEGER EXPOSURE" tells this application to find a FITS keyword of EXPOSURE and extract its value as an integer. If you wanted to estimate the dark time from a knowledge of the start and end times (TAI0 and TAI1):

The function may use any of the usual Fortran operators; +, -, *, /, ** and many others that are supported by the TRANSFORM package (SUN/61).

Functions are allowed to not contain any FITS-keywords in which case the extension item will be assigned to the value, so for instance numerical constants may be given:

In this way import tables could actually be used to set all the required values in the CCDPACK extension (but see PRESENT also).

Characters strings cannot be manipulated by functions so a single special format for translating their values is provided. The name of the destination extension item and (optionally) its type are given as usual followed by a FITS-keyword which contains the string to be translated. This is then followed by statements which translate an "input" string into an "output" string, i.e.:

So for instance if you wanted to translate frame types to those recognised by CCDPACK you might use something like:

Which would compare the value of the FITS-keyword OBSTYPE with the strings "OBJECT", "FF" and "ZERO" (case insensitive) and convert these into the values in the right-hand side of the equals sign.

Logical data types are restricted to a single keyword whose value must be "YES", "TRUE", "T", "Y" for TRUE or "NO", "FALSE", "N", "F".

The FITS keywords may be hierarchical, and on the whole are specified simply by giving their name in the normal way. However, there is one special case: if the value of a FITS header is known to be a string of the form ’[A:B,C:D]’ the numbers A, B, C and D may be extracted individually by appending ’<X1>’, ’<X2>’, ’<Y1>’ or ’<Y2>’ respectively to the name of the keyword. Hence:

would set the extents from the first two fields of a suitably formatted TRIMSEC header.

Fields in the table may be separated by commas if desired, any amount of white space and tabs are also allowed. Comments may be placed anywhere and should start with the characters "#" or "!". Continuation onto a new line is indicated by use of "-".

The CCDPACK extension of an image may contain the following items. The names and types of the extension items are those as used in import tables. More complete descriptions of the items can be found with the applications that use these values.