Novel coating and photo-fabrication techniques for astronomy
Proceedings of SPIE - The International Society for Optical Engineering 5494 (2004) 562-565
Abstract:
In this paper we describe two coating and fabrication techniques we have developed applicable to astronomical instrumentation with particular emphasis on the FMOS instrument for the Subaru telescope.MUSE opto-mechanical design and performance
Proceedings of SPIE - The International Society for Optical Engineering 5492:PART 2 (2004) 909-920
Abstract:
The MUSE (Multi Unit Spectroscopic Explorer) instrument is a second-generation integral-field spectrograph candidate for the VLT, operating in the visible and near IR wavelength range (0.465-0.93 μm). It is combining a large 1' × 1' Field of View with a spectral resolution of 3000 and a spatial resolution of 0.2" coupled to a sophisticated ground-layer Adaptive Optics (AO) system. After a brief summary of the major instrumental requirements, we will focus on the opto-mechanical design of MUSE, including core subsystems such as the Fore-Optics, the Image Slicers and the Spectrographs, the Structure and the Calibration Unit. The most creative trends of the instrument will be underlined, such as the specific choices adopted to reduce the costs, weight and volume of the Slicer and Spectrograph units, that need to be manufactured and installed on the VLT Nasmyth platform into twenty-four replicas. Finally, a realistic estimate of the expected performance (in both throughput and image quality), and the future development program for the forthcoming detailed design phase will be presented.The current status of the UK-FMOS spectrograph
Proceedings of SPIE - The International Society for Optical Engineering 5492:PART 3 (2004) 1362-1370
Abstract:
FMOS is a near-IR OH-suppressed multi-fibre fed spectrograph for the Subaru telescope. The spectrograph will accept 200 optical fibres from the ECHIDNA positioner system at the 30arcmin Prime focus of the telescope. We will describe the recent activities here in the UK in progressing the instrument from its conceptual phase through detailed design and into manufacture. A variety of technical areas will be described including: the opto-mechanical system design and construction, development of the HAWAH-II detector control system, the thermal system design & control and OH suppression techniques.Galaxy groups in the two-degree field galaxy redshift survey: The luminous content of the groups
Monthly Notices of the Royal Astronomical Society 355:3 (2004) 769-784
Abstract:
The Two-degree Field Galaxy Redshift Survey (2dFGRS) Percolation-Inferred Galaxy Group (2PIGG) catalogue of ∼29 000 objects is used to study the luminous content of galaxy systems of various sizes. Mock galaxy catalogues constructed from cosmological simulations are used to gauge the accuracy with which intrinsic group properties can be recovered. It is found that a Schechter function is a reasonable fit to the galaxy luminosity functions in groups of different mass in the real data, and that the characteristic luminosity L * is slightly larger for more massive groups. However, the mock data show that the shape of the recovered luminosity function is expected to differ from the true shape, and this must be allowed for when interpreting the data. Luminosity function results are presented in both the bJ and rF wavebands. The variation of the halo mass-to-light ratio, T, with group size is studied in both of these wavebands. A robust trend of increasing T with increasing group luminosity is found in the 2PIGG data. Going from groups with b] luminosities equal to 1010 h-2 L ⊙ to those 100 times more luminous, the typical b J-band mass-to-light ratio increases by a factor of 5, whereas the rF-band mass-to-light ratio grows by a factor of 3.5. These trends agree well with the predictions of the simulations which also predict a minimum in the mass-to-light ratio on a scale roughly corresponding to the Local Group. The data indicate that if such a minimum exists, then it must occur at L ≲ 1010 h-2 L⊙, below the range accurately probed by the 2PIGG catalogue. According to the mock data, the bJ mass-to-light ratios of the largest groups are expected to be approximately 1.1 times the global value. Assuming that this correction applies to the real data, the mean bJ luminosity density of the Universe yields an estimate of Ωm = 0.26 ± 0.03 (statistical error only). Various possible sources of systematic error are considered, with the conclusion that these could affect the estimate of Ωm by a few tens of per cent.The 2dF galaxy redshift survey: The local E+A galaxy population
Monthly Notices of the Royal Astronomical Society 355:3 (2004) 713-727