The GRAVITY instrument software / High-level software

TL;DR

GRAVITY's complex software system integrates multiple subsystems and high data rates to enable precise interferometric observations at the VLTI, demonstrating advanced performance and stability requirements.

Contribution

This paper presents an overview of the high-level software architecture and key applications of the complex GRAVITY instrument system for the VLTI.

Findings

Successful integration of subsystems with high data throughput

Implementation of acquisition and data merging applications

Achieved stable and performant system operation

Abstract

GRAVITY is the four-beam, near- infrared, AO-assisted, fringe tracking, astrometric and imaging instrument for the Very Large Telescope Interferometer (VLTI). It is requiring the development of one of the most complex instrument software systems ever built for an ESO instrument. Apart from its many interfaces and interdependencies, one of the most challenging aspects is the overall performance and stability of this complex system. The three infrared detectors and the fast reflective memory network (RMN) recorder contribute a total data rate of up to 20 MiB/s accumulating to a maximum of 250 GiB of data per night. The detectors, the two instrument Local Control Units (LCUs) as well as the five LCUs running applications under TAC (Tools for Advanced Control) architecture, are interconnected with fast Ethernet, RMN fibers and dedicated fiber connections as well as signals for the time synchronization. Here we give a simplified overview of all subsystems of GRAVITY and their interfaces and discuss two examples of high-level applications during observations: the acquisition procedure and the gathering and merging of data to the final FITS file.