1 Introduction

The primary goal of TAROT ([Boër et al. 1999]) is the detection of optical counterparts of GRB sources. Hence TAROT is an automated ground based observatory able to process both alerts from a variety of sources (CGRO/BATSE, SAX, HETE-II), and normal requests of observations. The TAROT software has 5 different autonomous modules, interacting as shown in Fig. 1.

  

Figure 1: Connections between TAROT modules

- The OBSERVATION REQUESTOR is a module that enables anyone to send a proposal of observation to TAROT. The request, will then join the request database.

- The MAJORDOME is the TAROT software module able to optimally schedule observations.

- The CONTROL is the module which is in charge of the actual observatory control and monitoring. Whenever it receives a socket from the MAJORDOME, it actives the CCD CAMERA and images the requested position.

- The CCD CAMERA is for now a commercial Apogee Camera, but we are about to use our own made camera that will be able to read a frame in less than a second.

- The DATA PROCESSING software is composed of TAITAR ([Bringer 1997]), which is the image processing software developed for the purpose of TAROT. The complete analysis of a frame is done in 4 steps ([Irwin 1985]; [Bertin et al. 1996]): estimation of the sky background, thresholding, deblending, and photometry. TAITAR then compares each object found on the new frame with the TAROT database in order to detect a variable source or an optical counterpart of a GRB source as soon as possible (i.e. within few minutes). We have also developed a cloud detection algorithm based on flux measurement of reference sources evenly spaced over the sky which allows us to give a map of the cloud coverage, and an automated focus determination.

We present hereafter the MAJORDOME module, and the various observation modes.