MOONS fibre positioning module: instrument build overview

Abstract

MOONS (Multi-Object Optical and Near-infrared Spectrograph) is a third-generation visible and near-infrared spectrograph for the ESO Very Large Telescope, currently nearing the end of the assembly phase. The three channel spectrograph is fed via a fibre positioning module (FPM) which configures the location of 1001 fibres. The robotic fibre positioning units (FPUs) have been jointly developed by the UK Astronomy Technology Centre (UKATC) and MPS Microsystems (MPS) and provide a high-performance multiplexed focal plane with excellent transmission characteristics. An overview of the as-built mechanisms and supporting infrastructure is presented, with details on the extensive calibration process carried out. The integration process to date will be described, including a discussion of key lessons learned.

MOONS – Multi Object spectroscopy for the VLT: Design and testing of the MOONS metrology system

“…The MOONS FPUs are verified and calibrated using a dedicated verification rig (see [3]). While the FPUs have an excellent repeatability, a gearbox calibration of the FPUs is necessary to ensure that each FPU can reach the correct angle.…”

“…The sub-system is designed to accurately determine the physical location of the fibre positioning units (FPUs) in the plate reference system at any instance required during operations. An overview of the MOONS instrument, FPUs, and the metrology system in context can be found in [1], [2], and [3].…”

MOONS – multi object spectroscopy for the VLT: overview and instrument integration update

“…These are briefly described in the subsequent subsections together with an update on their integration procedure. A detailed description of all MOONS components can be found in [1] and in dedicated papers for the different subsystems [2], [3], [4], [5], [6], [7], [8], [9]. The MOONS RFE is mounted to the telescope and contains the focal plate and fibre positioning system used to align the optical fibres to their desired on-sky locations.…”

“…As of late June 2022, 659 FPUs are already fully verified, calibrated, and installed in the MOONS focal plate. Details can be found in [6].…”

MOONS fibre positioner control and path planning software

“…2.1 Mechanical Design MOONS fibre positioners have a two-armed design, as described in [2]. Each positioner can swivel around a central (alpha) axis.…”