1. Introduction

Xselect is a command line interface to the Ftools, for X-ray astrophysical analysis. It has four major functions:

• to organize the input of data through the observation catalogue, and store it internally for easy use.

• to enter intensity, phase, region, detector, grade, event file column, spectral, and timing filters, which will be applied to the event data.

• to make good time intervals (GTI) by applying selection criteria to the Housekeeping and auxiliary filter data.

• to extract images, light curves and spectra from the event data, using the entered filters, as well as the GTI created by the applied selections.

Xselect also contains routines of importance for specific missions. Currently, there are only ASCA specific commands, namely sisclean, gisclean, faint and fast. Xselect can be set up to support any new mission or instrument that does not require mission-specific routines simply by editing the mission database file (xselect.mdb). The mission database file distributed with xselect currently supports ASCA, ASTRO-E2, ASTROSAT, BBXRT, BurstCube, CALET, Chandra (under its pre-launch name AXAF), EINSTEIN, EXOSAT, HALOSAT, Hitomi (ASTRO-H), INTEGRAL, IXPE, MAXI, NICER, NuSTAR, ROSAT, BeppoSAX (SAX), SPECTRUM-RG, Suzaku, Swift, XL-Calibur, XMM-Newton, XRISM, and XTE.

In addition, there are routines to plot up various aspects of the event data, and of the HK and auxiliary filter data.

There are also general utility commands to view the internal state of Xselect, to view the raw data files, to clear various selections, data choices, etc., and to save the products of the analysis.

This users' guide has two main sections. The overview provides a brief tutorial on the use of Xselect while the commands section describes the individual commands in more detail. The appendices describe how to add new missions to Xselect, how the command line interface works, and the names of the temporary files created by Xselect.

A note on the usage of this manual before we proceed: each Xselect session is given a session prefix, which is prepended to the names of the product files, and appears in the prompts. In the rest of this manual, we will use the default session name: xsel. Replace this with your own session name for all the Xselect temporary files.