Keywords: clic

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# 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` .

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