13.1 Introduction

13.1.1 Contents of the account

At the first login on a new project account, you should find five directories:

1. reports: It contains all the pre-calibration performed by the Astronomer on Duty (AoD) on the site. This subdirectory is in read access only. For a given observing date, you should find the following compressed files: 28-feb-2001-x007.hpb.gz, the header file containing the calibration curves of the data; 28-feb-2001-x007.ps.gz, the PostScript file containing the result of this calibration. This file should be carefully read before starting a new calibration. show-28-feb-2001-x007.ps.gz is the PostScript file corresponding to a first look of the data. It includes meteo conditions (wind, mm of water, system temperature) but also pointing and focus errors. In many cases, this file can help to interpret dubious data. This file should also be read carefully before starting calibration. The file x007.note are notes written by the AoD on the site. This file is updated at each period of observations. It gives important information about the data quality and possible problems.
2. headers: It initially contains a copy of reports. Files should be uncompressed and data calibration should be performed in this subdirectory. This is the default directory of CLIC. However before activating CLIC, it is better to move to this subdirectory using the shell command: ``cd $$/headers''.
3. maps: This subdirectory, empty at the beginning, should contain at the end all the $uv$ tables and the maps produced. Using the CLIC procedure ``Write A UV Table'', the $uv$ tables are created by default in this directory which is also the default directory for GRAPHIC and MAPPING.
4. tmp/DATA: This subdirectory contains the raw data files (IPB) and their corresponding log files. In the example presented above, it would contain: H228X007.IPB, H228X007.OBS, H228X007.RDI. Access to this directory and to the raw data files is automatically handled by CLIC.
5. DATA: Most of the time this directory is empty. However, it can contain some IPB files and their corresponding log files. Like in the case of tmp/DATA, its use is transparent. The reducer does not need to know the exact location of the raw data files on her/his account. CLIC handles it for him/her.

Note that only the directories reports, headers and maps are saved on CDroms by the automatic procedure savproj.

13.1.2 Before starting the data reduction

The compressed PostScript files in headers containing the calibration curves performed by the AoD must be gunzipped and printed. Then, they must be carefully studied in order to determine the general quality of the data and find possible problems which are usually mentioned in the project.note file (e.g. x007.note) written by the AoD during the pre-data reduction process.

13.1.3 Activating the CLIC environment

CLIC is available by typing in the directory headers

$ CLIC

Under CLIC, there are several procedures available:

1. File: To open a new header (hpb) or data (IPB) file
2. Raw Data File: To open a raw data file (IPB)
3. Raw Data File Directories: To define the location of raw data file directories
4. First Look: Instrumental and meteorological conditions during the observations (see §2)
5. Standard Calibration (2 receivers): To calibrate raw data (see §3)
6. Self-Cal on a point source: To self calibrate the phase
7. Simple Check: To do simple checks on the data
8. Holography Reduction: To reduce holographic data
9. Write A UV Table: To produce the visibility table

Useful procedures to calibrate data are 1) ``First Look'', 2) ``Standard Calibration (2 receivers) '' and 3) ``Write A UV Table''.