 | Data Interface Control Document | Top Back Next |
Observation preparation tools provide the means to create and edit Observation Blocks as the basic unit of an executable sequence of Templates . Each template, in term, requires a given input configuration or parameter list, described by a so-called template signature . These parameters are stored in a format called Parameter File Format . Any template corresponds with a certain predefined mode of observation, and has consequently a Reference Setup File attached to it. Reference setup-files list the default configuration of all elements in the light path, and are also written in the parameter file format.
Observation blocks can be represented in Parameter File Format . They include information on the programme that owns the block, scheduling requirements and links to other blocks. They also include or refer via the templates to Setup Files for setting target positions, instrument and detector configurations, all of which can be re-used in a number of observations, e.g. when a list of target pointings are to be observed with the same instrumental configuration.
From the observation block information, the VLT Control Software (VCS) will eventually generate setup-commands for its own operations. Doing so it will complement the information contained in the reference setup-file corresponding with the running template.
Many VLT files containing control information are written in the Parameter File Format. This is the case for e.g. setup-files, instrument configuration files and template parameter files. These files consist of a mandatory header and parameter records. Their syntax is optimized for fast parsing by the VLT Control Software and therefore it differs from other formats described in this document (see [2] ).
A parameter record is written with the following syntax:
<short FITS keyword> value ; [# comment ]
<short FITS keyword> is an ESO keyword following the same naming convention as defined in section 4.3 except that for technical reasons the subsystems, categories and parameters of hierarchical keywords are connected by dots `.' rather than spaces (e.g. INS.FILT1.NAME instead of INS FILT1 NAME ); also, the prefix HIERARCH ESO is not used. This syntax is called short FITS keywords .
value can be one of the values defined in section 4.1 , however, strings must be enclosed in double rather than single quotes, i.e. "string" . The value part must be finished with a semicolon `;' and must be given on the same line. The total length of a PAF record is currently limited to 256 characters, however, it is planned to lift this restriction in future software releases.
Optional comments can be included at the end of a line by prefixing them with the hash sign (" # ").
The header consists of a number of records identifying the purpose and type of the parameter file. Header records are mandatory. Parameter header records are grouped in the PAF category. table 16 gives an example of a parameter file header.
PAF.HDR.START; # Marks start of header
PAF.TYPE "Template Signature"; # Type of parameter file
PAF.ID "SUSI/SOT02/0.1a"; # Parameter file ID
PAF.NAME "SOT02"; # Parameter file NAME
PAF.DESC "SUSI Imaging in jitter mode";
PAF.CRTE.NAME "A. M Chavan"; # Author of par. file
PAF.CRTE.DAYTIM "1996-06-10T09:10:01"; # Date and time of creation
PAF.LCHG.NAME "A. M Chavan"; # Author of last change
PAF.LCHG.DAYTIM "1996-06-22T16:21:34"; # Date and time of last change
PAF.CHCK.NAME "chksum-tpl/1.0"; # Appl. checking par. file
PAF.CHCK.DAYTIM "1996-06-22T16:22:50"; # Date and time of last check
PAF.CHCK.CHECKSUM "hcHjjc9ghcEghc9g"; # Parameter file checksum
PAF.HDR.END
The keyword PAF.TYPE identifies the kind of parameter file. It must take one of following the values:
"Reference Setup"
"Instrument Setup"
"Detector Setup"
"Telescope Setup"
"Reference Configuration"
"Configuration"
"Ambient Data"
"Template Signature"
"OB Description"
.
It is also possible to write a verbose description of the parameter file within the header. This description must be written as a number of description lines:
PAF.DESC <description heading>;
PAF.DESC <description line 2>;
PAF.DESC . . .
PAF.DESC . . .
The keyword PAF.CHK.CHECKSUM provides means by which the parameter file is protected against changes. The checksum is computed and written by the checking application according to the algorithm given in section 4.3.1.3 .
The header always starts with a PAF.HDR.START keyword and finishes with PAF.HDR.END .
Reference setup files can contain after the header a so-called protected region , which is a list of setup parameters which should not be overridden in this particular mode of observation. This region starts with a PAF.PROT.START keyword and finishes with PAF.PROT.END .