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Abstract:

We present the consolidated scientific case for multi-object spectroscopy with the MOSAIC concept on the European ELT. The cases span the full range of ELT science and require either ‘high multiplex’ or ‘high definition’ observations to best exploit the excellent sensitivity and wide field-of-view of the telescope. Following scientific prioritisation by the Science Team during the recent Phase A study of the MOSAIC concept, we highlight four key surveys designed for the instrument using detailed simulations of its scientific performance. We discuss future ways to optimise the conceptual design of MOSAIC in Phase B, and illustrate its competitiveness and unique capabilities by comparison with other facilities that will be available in the 2020s.

Abstract:

In this work we present the coatings of the spectrograph red camera of WEAVE -the new multiobject survey facility for the 4.2m William Herschel Telescope. The initial requirements of WEAVE red camera lenses, with reflectances as low as 0.4% through the wavelength interval from 590 nm to 959 nm at angles of incidence of 18° +/- 17° represented a challenge for both design and production. Based on initial requirements, several solutions to the same problem were achieved and tested. The customized designs have been continuously improved through theoretical and experimental approximations. From transmittance measurements at normal incidence we developed a method to determine the reflectance at different angles of incidence. We show the designs and coating transmittance obtained for the four glasses on test runs to guarantee that the designs were achievable experimentally. Additionally, we present the reflectance obtained on the lenses of the the first four lenses of WEAVE red camera.

Abstract:

The Observation Queue Scheduler (OQS) for WEAVE is described in this paper, with particular emphasis on the scheduling algorithm. WEAVE is the new 2-deg field of view multi-object (1000 multiplex) spectroscopy facility (R5000 and R20000) at the 4.2-m William Herschel Telescope. The OQS helps to maximize the scientific impact of WEAVE observations by optimising the schedule of the observing blocks, taking into account the science priority, required instrument configuration and observing constraints. On a nightly basis the OQS will assist the observer in creating a flexible queue of suitable observing blocks to be executed. It will be also possible to run a version of the OQS for extended periods of time to provide guidance on the longer-term planning of WEAVE surveys.

Abstract:

Product Assurance is an essential activity to 91̽»¨ the design and construction of complex instruments developed for major scientific programs. The international size of current consortia in astrophysics, the ambitious and challenging developments, make the product assurance issues very important. The objective of this paper is to focus in particular on the application of Product Assurance Activities to a project such as MOSAIC, within an international consortium. The paper will also give a general overview on main product assurance tasks to be implemented during the development from the design study to the validation of the manufacturing, assembly, integration and test (MAIT) process and the delivery of the instrument.

Abstract:

WEAVE is the next-generation spectroscopic facility for the William Herschel Telescope (WHT) 1,2. WEAVE offers multi-object (1000 fibres) and integral-field spectroscopy at two resolutions (R ~ 5000, 20000) over a 2-deg field of view at prime focus and will mainly provide follow up of ground-based (LOFAR) and space-based (GAIA) surveys. The Observatory Control System (OCS) is responsible for providing the software control and feedback framework through which WEAVE will be operated. This paper summarizes the design of the different OCS subsystems and the interfaces between them and other WEAVE components. In the remainder of this paper, Section 2 outlines the other WEAVE systems with which the OCS interacts, Section 3 describes the system architecture, Section 4 comments on system-architecture decisions, Section 5 describes the main components of the OCS, Section 6 outlines the life-cycle of an OCS Observing Block and, finally, Section 7 gives an overview of the OCS testing plan.