Astronomical instrumentation

Abstract:

Current simulation and experimental investigatory work is going on into the performance of slicer and lenslet IFS designs. The aim of this work is to determine which technology holds the best promise for achieving the highest contrasts with EPICS on the E-ELT. Results from Spectral Deconvolution methods for high contrast detections are presented, both on sky images from AB Dor C observations using SINFONI on the VLT and improvements to the algorithms made through use of EPICS simulation data. Using these simulations, only containing photon and speckle noise, we have been able to detect simulated planets down to a contrast of 1010 located less than 1" from the parent star. The effects of spectral resolution and wavelength range on high contrast observations are discussed. Shortening the wavelength range increases the inner working angle. It is seen that an outer working angle is also reached that decreases with spectral resolution. The limit on the inner working angle can be overcome partly by increasing the wavelength range of the instrument although another inner working angle limit will be reached if a coronagraph is used. The limit of the outer working angle can also be overcome by increasing the spectral resolution of the instrument or possibly by making an IFS that produces an output with a constant spectral resolution, R,instead of constant Δλ.This is still a work in progress.

Abstract:

FMOS: the Fiber Multiple-Object Spectrograph is the next common-use instrument of the Subaru Telescope, having a capability of 400 targets multiplicity in the near-infrared 0.9-1.8μm wavelength range with a field coverage of 30- diameter. FMOS consists of three units: 1) the prime focus unit including the corrector lenses, the Echidna fiber positioner, and the instrument-bay to adjust the instrument focus and shift the axis of the corrector lens system, 2) the fiber bundle unit equipping two fiber slits on one end and a fiber connector box with the back-illumination mechanism on the other end on the bundle, 3) the two infrared spectrographs (IRS1 and IRS2) to obtain 2×200 spectra simultaneously. After all the components were installed in the telescope at the end of 2007, the total performance was checked through various tests and engineering observations. We report the results of these tests and demonstrate the performance of FMOS.

Abstract:

The dusty molecular torus, cornerstone of the unified model of AGN, has been the subject of much observational and theoretical scrutiny in recent years, and much progress has been made with observations and models aiming to reveal, explain and predict its properties. ©2008: Instituto de Astronomía.

Abstract:

We describe the implementation of differential wavefront sampling(DWS) in optical alignment of a pupilsegmented telescope system. As a wavefront-based optical alignment method, DWS can efficiently provide estimations of misalignments present in an optical system by deliberately perturbing optical elements in a systematic manner. This has been demonstrated in our previous numerical studies with realistic uncertainties in wavefront measurements, motion control, and optical surface deformations, suggesting that the method has potential in optical alignment and phasing of pupil-segmented systems such as the future Extremely Large Telescopes (ELTs). The basic idea and procedures of DWS are first described. We then present and discuss preliminary simulations using the currently proposed European Extremely Large Telescope (E-ELT) as an example system.

Abstract:

The UK FMOS spectrograph forms part of Subaru's FMOS multi-object infrared spectroscopy facility. The spectrograph was shipped to Hilo in component form in August of 2007. We describe the integration sequence for the spectrograph, the results of cooldown tests using a new chiller unit fitted to the spectrograph at the telescope, and alignment tests of the spectrograph, gratings and OH-suppression masks. We present the first-light observations for the spectrograph from May 2008.