### 1 Introduction

CURSA1 (Catalogue Utilities for Reporting, Selecting and Arithmetic) is a package of Starlink applications for manipulating astronomical catalogues and similar tabular datasets. This manual describes Version 6.4 of CURSA. Though CURSA is primarily intended for use with astronomical catalogues it can be used equally well with other tabular data, such as a table of private astronomical results, or, indeed, data which are entirely non-astronomical, provided that they are in an appropriate format.

The facilities provided by CURSA include: browsing or examining catalogues, selecting subsets from catalogues, sorting catalogues, copying catalogues, pairing two catalogues, converting catalogue coordinates between some celestial coordinate systems, plotting finding charts and photometric calibration. Also, subsets can be extracted from a catalogue in a format suitable for plotting using other Starlink packages, such as PONGO.

CURSA can access catalogues held in either the popular FITS table format, the Tab-Separated Table (TST) format or the Small Text List (STL) format. Both ASCII and binary FITS tables can be read, though only binary FITS tables can be written. Catalogues in the STL and TST formats are simple ASCII text files which can be created with a text editor. Unlike the other formats which CURSA can access, the STL format is specific to CURSA. Nonetheless, the STL format exists in order to allow easy access to both private tables and versions of standard catalogues held as text files. It is usually straightforward to create an STL catalogue from a text file containing a private list or catalogue. CURSA includes a facility for automatically converting text versions of catalogues obtained from the Centre de Données astronomiques de Strasbourg (CDS) into the STL format. CURSA also has some facilities for accessing remote on-line catalogues via the Internet.

CURSA is available on all the variants of Unix currently supported by Starlink. The following section briefly describes some sources of catalogues in suitable formats. Subsequent sections introduce some general information about CURSA and the later sections describe the individual applications. Two tutorial examples (‘recipes’ in the jargon of cookbooks) of using CURSA are included in SC/6: The CCD Photometric Calibration Cookbook[22].

1Cursa is the common name for $\beta$ Eridanus. It is of Arabic origin and derives from an abbreviation of the name of an asterism involving $\lambda$, $\beta$ and $\psi$ Eri and $\tau$ Ori: ‘the Foremost Footstool of Orion’. These details come from a Short Guide to Modern Star Names and Their Derivations by P. Kunitzsch and T. Smart[18].