# Introduction

CLIC is a software developped at IRAM to support the calibration of the data from the NOEMA interferometer. It stands for Continuum and Line Interferometric Calibration and is part of the GILDAS package. We refer to the GILDAS documentation for further information on the GILDAS software. CLIC uses code from the so-called GILDAS kernel like SIC for command interpretation or GREG for the plots. It also uses routines from ASTRO to do astronomical computations. CLIC uses a specific binary format for data files (see section 3) produced at the NOEMA observatory by an online reduction software called RDI, that itself uses the CLIC libraries (for data writing, atmospheric calibration, pointing and focus solving, etc.).

CLIC is also adapted to the NOEMA observatory in terms of commands. It provides the tools to do the required calibrations using the NOEMA nomenclature (for example, the presence of a noise source at NOEMA allows to align all spectral windows connected to a baseband in amplitude and phase, so the passband calibration is then done per baseband and applies to all the spectral windows that pertain to that baseband).

As part of the ALMA project, CLIC has been used to assess the performances of the ALMA antennas through holographies. A branch of CLIC has then been ported to TELCAL, the online calibration software of ALMA. This activity has led to the development of import capabilities, first as TI-FITS, then as ASDM. While these capabilities are deprecated using IRAM HEAD version, branches of CLIC are still used to reduce holographies for ALMA as previously mentioned and for the Yebes 40m telescope (using TI-FITS). IRAM has also developped a package, called MRTHOLO, that process IMB-FITS from the 30m telescope and produces IPB file, for reduction of 30m holographies within CLIC .

The output files after calibration are uv tables, in the GILDAS data format (GDF). Export possibilities are provided throuhg UV-FITS (see MAPPING documentation).

This document describe first how CLIC files are organized, then describes the commands. The details of NOEMA data calibration are left to the documentation of the pipeline.

The appendix contains the online help of CLIC .