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Abstracts of talks on Monday March 22nd

Carlos Allende Prieto: APOGEE: H-band multi-object spectroscopy around the Galaxy

The Apache-Point Observatory Galactic Evolution Experiment will obtain 100,000 high-resolution stellar spectra in the H-band using the SDSS 2.5-m telescope and a new criogenic spectrograph fed by 300 fibers. Our studies indicate that with a resolving power of ~ 30,000 and a S/N of ~ 100, the wavelength window between 1.52 and 1.68 um, will allow us to determine abundances for 15 chemical elements in cool giants. In this brief overview I will focus on the most interesting aspects of the APOGEE spectrograph.

Marc Balcells: Introductory talk

ING management, the ING Board, the Science Advisory Committee and the funding agencies are actively planning the next decade for the observatory. Recent reviews of UK and European astronomy have provided detailed recommendations to guide this planning. But it is ultimately the user communities who need to tell us what they want from the ING. At this workshop we encourage open discussion of a broad range of topics such as science priorities, requirements for new instrumentation, and operational modes.

David Carter: Galaxy clusters

I will be talking about work on clusters of galaxies, including results from the Coma project, and plans to exploit the HST MCT survey on distant clusters.

Francisco Javier Castander: The PAU narrow-band cosmology survey

The PAU collaboration obtained funding from the Spanish Consolider-Ingenio 2010 programme in 2007 to lead the implementation of a world-class experiment to study dark energy. For that purpose it proposed to build a large area camera to carry out a wide field survey to undertake such study. The main innovative idea is to use narrow band filters (~100 A wide) covering the optical spectral range (4500-8500 A) combined with broad band filters to characterise the spectral energy distribution of all observed objects and thus determine the galaxy redshifts with photometric techniques with a resolving power equivalent to a low resolution spectrograph.

Janet Drew: Milky Way surveys - IPHAS, UVEX

This talk will identify the nature of these two surveys using the INT/WFC and briefly discuss the follow-up observations they have and are likely to stimulate. IPHAS, taking data in r,i,H-alpha is practically complete and is undergoing uniform calibration currently: UVEX is about one-third of the way through its follow-on u,g,r,HeI-5876 programme. Applications of these surveys range from the discovery of very rare object types through to the first comprehensive 3-D extinction mapping of the Galactic Plane.

Boris Gaensicke: Time domain

Armando Gil de Paz: Studying nearby disk galaxies with MEGARA, the proposed wide-field IFU & MOS for GTC

The current status of MEGARA, the proposed intermediate-spectral resolution wide-field IFU & MOS for GTC, will be presented. I will focus on the prospects of MEGARA for the study of stellar populations and kinematics in nearby disk galaxies. Finally, I will also discuss possible synergies between MEGARA and a similar but complementary instrument at WHT.

Gerry Gilmore: Galactic archaeology

An outline of the opportunities and context for observing Galaxy evolution relevant to WHT and INT

Amina Helmi: MOS science on a 4-m telescope

I will discuss the scientific needs for wide-field MOS in the area of Galactic studies. I will present a few science cases and the requirements these impose on the characteristics of the MOS.

Artemio Herrero: Massive star research at WHT

We present a view of our current research on massive stars using the WHT. The versatility of WHT instrumentation allows us to carry on this reserach in Galactic and extragalactic objects, at many different wavelength ranges and combining photometric and spectroscopic techniques. Nevertheless, there is still room for improvements.

Mike Irwin: Imaging surveys and requirements for spectroscopic follow up in Galactic Archaeology

Ofer Lahav: Cosmology surveys

Craig Mackay: Diffraction-limited imaging in the visible on the WHT

Adaptive optics techniques have delivered near-diffraction limited imaging in the near infrared (2.2 ?) but in the visible they have been much less successful. Faint object diffraction limited imaging in the visible from the ground has recently been demonstrated on a 5 m telescope with more than twice the resolution of Hubble for the first time, using a combination of low order AO correction with Lucky Imaging. A new approach to the design of high efficiency, low order adaptive curvature sensors which use photon counting CCD detectors will allow the use of much fainter guide stars to correct much of the atmospheric turbulence. This approach would allow the 4.2 m WHT to routinely deliver about twice the resolution of Hubble in the visible for a wide range of astronomical programmes. The investment required would be relatively small and could be developed relatively quickly giving the WHT a valuable and unique capability.

Reynier Peletier: Nearby unresolved galaxies with the WHT

In this talk I will discuss a number of ways how the WHT can remain an important player in the field of nearby unresolved galaxies in the next decade.

Rafael Rebolo: Substellar objects and exoplanets

Huub Rottgering: Follow-up of radio surveys

LOFAR, the Low Frequency Array, is a next-generation radio telescope that is being built in Northern Europe and expected to be fully operational at the end of 2010. It will operate at frequencies from 15 to 240 MHz (corresponding to wavelengths of 20 to 1.2 m). Its superb sensitivity, high angular resolution, large field of view and flexible spectroscopic capabilities will represent a dramatic improvement over previous facilities at these wavelengths. As such, LOFAR will carry out a broad range of fundamental astrophysical studies. The design of LOFAR has been driven by four fundamental astrophysical applications: (i) The Epoch of Reionisation, (ii) Extragalactic Surveys and their exploitation to study the formation and evolution of clusters, galaxies and black holes, (iii) Transient Sources and their association with high energy ob jects such as gamma ray bursts, and (iv) Cosmic Ray showers and their exploitation to study the origin of ultra-high energy cosmic rays. During this contribution we will first present the LOFAR project with an emphasis on the challenges faced when carrying out sensitive imaging at low radio frequencies. Subsequently, we will discuss LOFAR's capabilities to survey the low-frequency radio sky. Main aims for the planned surveys are studies of z>6 radio galaxies, diffuse emission associated with distant clusters and starbursting galaxies at z>2. Finally we will conclude with stressing the importance of the availability of an efficient MOS redshift machine to accomplish these goals.

Mark Sullivan: WHT and the next generation of wide-field transient surveys

4m-class telescopes are the workhorse facilities for spectroscopic follow-up of the new, next-generation wide-field transient surveys, such as the Palomar Transient Factory and PanStarrs-1. The UK has leadership roles in both these surveys and the UK's access to WHT/ISIS can play a key part in studying the physics of the transient events located with these surveys. We will discuss our current ISIS observing strategy and the collaboration between the two survey teams to maximise the science output of the jointly allocated time. We will show how queue, flexible, or even robotic observing would increase the productivity, impact, and timeliness of WHT's future scientific contribution.

Abstracts of posters on Monday March 22nd

Chris Benn, Kevin Dee, Tibor Agocs: ACAM - a new imager/spectrograph for the WHT

ACAM is a new wide-field imager/spectrograph, mounted permanently at a folded-Cassegrain focus of the 4.2-m William Herschel Telescope, since summer 2009. It's expected that ACAM will be used for a broad range of high-impact science programmes requiring rapid response (e.g. supernovae, gamma-ray bursts), or awkward scheduling (e.g. exoplanet transits), or the use of specialised filters (e.g. narrow-band Halpha imaging of low-red shift galaxies). We present here the optical and mechanical design.

Francisco Javier Castander et al.: The PAU camera

The PAU (Physics of the Accelerating Universe) collaboration is building an instrument, intended for the William Hershel Telescope prime focus, designed to perform a large area survey for cosmological studies. The idea is to use an alternative approach to measure the spectral energy distribution (SED) of galaxies using narrow band imaging instead of spectroscopy. The SEDs are sampled using ~ 40 filters ~ 100 A wide spanning the optical wavelength range to accurately measure photometric redshifts. The FoV is 1 degree, densely populated by 18 state of the art CCDs. The maximum vignetting is 50% of the focal plane. A pressurized liquid nitrogen tank will feed a boiler inside the cryostat. The CCD's will be kept at 170K and temperature homogeneity will be achieved with a coldplate, acting as a heat spreader and thermal capacitance smoothing the cooling and heating ramps. Low read-out noise of the CCDs is being prepared using the Monsoon architecture developed by NOAO. The filters have to be placed as close as possible to the CCD detector surfaces on segmented exchangeable filter trays. An innovative jukebox-like exchanging mechanism inside the cryostat based on rolling hybrid bearings technology with tungsten disulfide as solid lubricant has been chosen to hold the movements inside the cryostat. Two independent servomotors with absolute encoders outside the cryostat through magnetic feedthroughs will motion the system.

Maria Luisa Garcia Vargas: Sliced-pupil gratings for increasing resolution of in-operation spectrographs

We have developed a new concept of gratings that consists on sandwiching a VPH between two prisms and slicing the pupil, in order to smooth the angle on the grating, and recovering the image on the detector. This allows to increase the spectral resolution (by a factor or 2 or 3) of an already-built instrument without changing the geometrical configuration either the rest of opto-mechanical components. We are building a prototype in collaboration with Universidad Complutense in Madrid (already under manufacturing phase) that will be ready in July 2010. This concept could be applied to some of the already existent WHT spectrographs.

Garik Israelian: Li and Be abundances in stars with exoplanets

Samantha Rix et al: Visiting instruments at the 4.2-m WHT

The 4.2-m William Herschel Telescope on La Palma is a popular platform for innovative visiting instruments. Some are geared to specific science programmes, while others extend the explorable 'photon parameter space' beyond that covered by the WHT's common-user instruments (e.g. by providing high time resolution, or high polarisation sensitivity). On average, the WHT hosts six visiting instruments each semester. We dsecribe some of these below, and highlight the attractions of bringing new visitor instruments to the WHT.

Miguel Santander-Garcia: The AF2 reduction pipeline

We present the pipeline for reducing data from AF2/WYFFOS (AutoFib2/Wide Field Fibre Optical Spectrograph). This software, written in IDL and soon available to the public, is able to perform full data reduction (including fibre to fibre sensitivity corrections and optimal extraction of the individual spectra) in a broad range of observing strategies. This pipeline will also be available in an user-friendly, quick-look version to be used at the telescope while carrying out observations.

Abstracts of talks on Tuesday March 23rd

Tibor Agocs: 2-degree WHT PF optical correctors

I present a conceptual design for two new refractive correctors for the prime focus of the 4.2m William Herschel Telescope, optimised to allow multi-object spectroscopy over a two degree field of view. The proposed designs satisfy the demanding requirement that the PSF be smaller than 0.5 arcsec (80% encircled energy) over a two degree FOV and a wavelength range of 380nm - 1000nm. I present the specifications and describe the design process for the corrector, which also acts as an atmospheric dispersion corrector (ADC). The design that I present satisfy the science requirements and forms the basis of a realistic manufacturable system.

Jeremy Allington-Smith: New ideas for highly-multiplexed spectroscopy

In the last few years, radically new ideas have been put forward for highly-multiplexed spectroscopy. These include the development of the Diverse Field Spectroscopy paradigm facilitated by new approaches to fibre bundle fabrication and the development of efficient optical switching networks. More radical yet is the Astrophotonics approach which seeks not only the removal of OH lines before dispersion (as already demonstrated) but also the development of miniaturised "spectrographs on a chip". Instruments using these ideass may provide exceptional service not only to WHT observers but also to future observatories using the WHT as a testbed.

Marco Azzaro: Fiber positioner development for survey instruments

The SIDE group has a valuable experience in fiber positioners for survey instruments. The group is formed around the collaboration of an industrial company (AVS) and a research institute (IAA), therefore it offers the unique capability of developing a product under strict standards both from the scientific and production/manufacture point of view. Our activity ranges from the design to fabrication and test of the hardware, electronics and control software. A prototype positioner is under test at the IAA and some preliminary results on its performance are already available.

Gavin Dalton: A 1st order VPH-based medium-high resolution spectrograph for WHT-MOS

I will describe a spectrograph design, based on the OPTIMOS-EVE design for the E-ELT which is perfectly matched to the prime-focus plate scale of the WHT and would yield high multiplex spectroscopy from R=5000 to R=30000 from a single spectrograph, working at 1st order with VPH gratings.

David King: Wide-field correctors for WHT: forward-Cassegrain options

Preliminary designs for a 2 degree field f/7 forward cassegrain focus as a possible alternative to prime focus will be discussed. Additionally, several spectrograph configurations covering both high resolution (R~40,000) and low resolution (R~5000) will be examined.

Ray Sharples: Instrumentation for cosmological surveys

I will discuss the instrumentation drivers for cosmological surveys with 4m-class telescopes and present some new designs for extreme-multiplex wide-field multi-slit spectrographs on such platforms.

Scott Trager: Specs for a wide-field IFU