Maureen A. Conroy

Hectospec, the mmt's 300 optical fiber-fed spectrograph

ABSTRACT The Hectospec is a 300 optical fiber fed spectrograph commissioned at the MMT in the spring of 2004. In the configuration pioneered by the Autofib instrument at the Anglo‐Australian Telescope, Hectospec’s fiber probes are arranged in a radial “fisherman on the pond” geometry and held in position with small magnets. A pair of high‐speed, six‐axis robots move the 300 fiber buttons between observing configurations within ∼300 s, and to an accuracy of ∼25 μm. The optical fibers run for 26 m between the MMT’s focal surface and the bench spectrograph, operating at \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textc...

Kinematics of NGC 2264 : Signs of cluster formation

We present results from 1078 high-resolution spectra of 990 stars in the young open cluster NGC 2264, obtained with the Hectochelle multiobject echelle spectrograph on the 6.5 m MMT. We confirm 471 stars as members on the basis of their radial velocity and/or Hα emission. The radial velocity distribution of cluster members is non-Gaussian, with a dispersion of σ ≈ 3.5 km s-1. We find a substantial north-south velocity gradient and spatially coherent structure in the radial velocity distribution, similar to that seen in the molecular gas in the region. Our results suggest that there are at least three distinguishable subclusters in NGC 2264, correlated with similar structure seen in 13CO emission, which is likely to be a remnant of initial structure in this very young cluster. We propose that this substructure is the result of gravitational amplification of initial inhomogeneities during overall collapse to a filamentary distribution of gas and stars, as found in simulations by Burkert & Hartmann (2004).

Accretion, Kinematics, and Rotation in the Orion Nebula Cluster: Initial Results from Hectochelle*

We present results from high-resolution spectra of 237 stars in the Orion Nebula cluster (ONC) obtained during two engineering runs with the Hectochelle multifiber echelle spectrograph on the 6.5 m MMT. The ONC is the nearest populous young (age ~ 1 Myr) cluster and is therefore an important object for studies of the evolution of protoplanetary disks. Using the high spectral resolution of Hectochelle, we are able to distinguish stellar accretion and wind emission-line profiles from nebular emission lines and identify accreting members of the cluster from H? profiles with greater accuracy than previously possible. We find 15 new members on the basis of Li ?6707 absorption and H? emission. Line profiles of H? of some objects that are not too contaminated by nebular emission show features characteristic of mass inflow and ejection. We also present rotational velocities as part of an initial investigation into angular momentum evolution of very young stars, confirming a difference between classical T Tauri stars and weak-line T Tauri stars that had been found from period analysis. Finally, we present an initial study of the radial velocity dispersion of the brighter stars in the central cluster. The very small dispersion derived, ?1.8 km s-1, is in good agreement with estimates from proper motions.

Calibration of the ROSAT High-Resolution Imager

The microchannel plate-based High Resolution Imager (HRI) is one of the focal plane instruments of the Rosat X-ray telescope that was launched on 1 June 1990. The calibration of the HRI is reported and preliminary results from the in-orbit calibration are presented. The quantum efficiency of the detector has been determined as a function of energy, the spatial variation of quantum efficiency, geometric nonlinearities, background, imaging performance, and UV sensitivity. Results of periodic tests of the temporal stability of the instrument are also reported.

The F/5 instrumentation suite for the Clay Telescope

The f/5 instrumentation suite for the Clay telescope was developed to provide the Magellan Consortium observer community with wide field optical imaging and multislit NIR spectroscopy capability. The instrument suite consists of several major subsystems including two focal plane instruments. These instruments are Megacam and MMIRS. Megacam is a panoramic, square format CCD mosaic imager, 0.4° on a side. It is instrumented with a full set of Sloan filters. MMIRS is a multislit NIR spectrograph that operates in Y through K band and has long slit and imaging capability as well. These two instruments can operate both at Magellan and the MMT. Megacam requires a wide field refractive corrector and a Topbox to support shutter and filter selection functions, as well as to perform wavefront sensing for primary mirror figure correction. Both the corrector and Topbox designs were modeled on previous designs for MMT, however features of the Magellan telescope required considerable revision of these designs. In this paper we discuss the optomechanical, electrical, software and structural design of these subsystems, as well as operational considerations that attended delivery of the instrument suite to first light.