Astronomical instrumentation

Abstract:

Echelle spectroscopy of [Si VI] 1.96 μm, [Mg VIII] 3.03 μm, and [Ar VI] 4.53 μm, using UKIRT+CGS4, shows the line pro les in PN NGC 6302 are singly peaked and unresolved even at R ∼ 20 000, with line widths less than 22 kms-1. A photoionized structure is evidenced by spatial and velocity stratification as a function of ionization potential. But a variety of models, with density and Te gradients, reproduce the spectrum equally well. Preliminary analysis of the 3000-10000 Å echellogram of NGC 6302, acquired at R ∼ 80 000 using VLT+UVES, confirms the stratified nebular structure, but yields intriguing results concerning the line profiles: [Ne V] 3426 Å is broader than [Ne IV] 4723 Å. These observations rule out the existence of an evacuated cavity, or hot bubble, at least on 1″ and 3 km s-1 scales. We do not confirm the broad wings in [Ne V] 3426 Å reported by Meaburn & Walsh (1980).

Abstract:

The first of two Gemini Multi Object Spectrographs (GMOS) has recently begun operation at the Gemini-North 8m telescope. In this presentation we give an overview of the instrument and describe the overall performance of GMOS-North both in the laboratory during integration, and at the telescope during commissioning. We describe the development process which led to meeting the demanding reliability and performance requirements on flexure, throughput and image quality. We then show examples of GMOS data and performance on the telescope in its imaging, long-slit and MOS modes. We also briefly highlight novel features in GMOS that are described in more detail in separate presentations, particularly the flexure compensation system and the on-instrument wavefront sensor. Finally we give an update of the current status of GMOS on Gemini-North and future plans.

Abstract:

In 1996, it was proposed to build a near-infrared imager for the 3.8-m UK Infrared Telescope in Hawaii, to exploit the 1024 pixel format detectors that were then becoming available. In order to achieve a fast delivery, the instrument was kept simple and existing designs were reused or modified where possible. UFTI was delivered within 2.5 years of the project start. The instrument is based around a 1k Rockwell Hawaii detector and a LSR Astrocam controller and uses the new Mauna Kea optimised J,H,K filter set along with I and Z broad-band filters and several narrow-band line filters. The instrument is cooled by a CTI cry-cooler, while the mechanisms are operated by cold, internal, Bergelahr stepping motors. On UKIRT it can be coupled to a Fabry-Perot etalon for tunable narrow-band imaging at K, or a waveplate for imaging polarimetry through 1-2.5μm; the cold analyser is a Barium Borate Wollaston prism. UFTI was designed to take full advantage of the good image quality delivered by UKIRT on conclusion of the upgrades programme, and has a fine scale of 0.09 arcsec/pixel. It is used within the UKIRT observatory environment and was the first instrument integrated into ORAC, the Observatory Reduction and Acquisition Control System. Results obtained during instrument characterisation in the lab and over the last 3 years on UKIRT are presented, along with performance figures. UFTI has now been used on UKIRT for several hundred nights, and aspects of instrument performance are discussed.