L. Weitzel

ROGUE - the Rapid Off-axis GUider Experiment

Near infrared imaging spectroscopy at spatial resolutions of 0.5 arc seconds will fundamentally change our understanding of active galactic nuclei. This long desired capability has been achieved for the first time by the latest generation of MPE instruments, ROGUE and 3D. ROGUE, the rapid off-axis guider experiment, is a low order adaptive optics system performing tip-tilt correction in the near infrared using natural guide stars. Three-dimensional is the MPE near infrared imaging spectrometer capable of simultaneous imaging and spectroscopy of the entire H and K atmospheric windows. ROGUE is capable of tip-tilt correction at 40 Hz in a 4 arc-minute diameter isokinetic patch using natural guide stars as faint as 18th magnitude. We discuss the design of the instrument, present the first astronomical results, and outline future efforts to incorporate variable image scales.

Kinematics and distribution of dense gas in Seyfert nuclei

Abstract We report on high spatial and spectral resolution observations of the distribution, physical parameters and kinematics of the molecular interstellar medium toward the nuclei of three nearby active galaxies. The data consist of high resolution interferometric observations of the HCN and CO J = 1 → 0 lines, single dish observations of several mm/submm isotopic lines of HCN and CO, and subarcsecond resolution imaging spectroscopy of the near-IR K-band.

3D: A new tool for probing the stars and ISM in AGN

Abstract 3D, the new MPE NIR imaging spectrometer, provides us with a unique opportunity to probe in detail the structure of the stars, ionized gas, and hot molecular gas in the very centers of AGN. The instrument delivers data cubes with 16×160.5″ pixels which are 256 spectral channels deep. Thus, in a single observation we are able to obtain data on the entire K-Band over an 8″ × 8″ field of view, with a spectral resolution of R = λ Δλ = 1000 . In this paper we detail the working principles behind the instrument, and show first results from observations of the inner regions of the Seyfert 1 galaxy NGC7469 made at the Calar Alto observatory.

Observational Evidence for a Compact Dark Mass at the Galactic Center

We present improved recent results from near-infrared high spatial resolution speckle observations with the MPE SHARP 1 camera at the NTT as well as imaging spectroscopic observations with the MPE 3D spectrometer at the ESO-MPIA 2.2m telescope, both at La Silla, Chile. The new K-band speckle maps reach K magnitudes of about 16 and resolve the previously found object at the position of the radio source Sgr A*(R) into a small cluster of compact sources. With one exception, their polarizations are similar to other sources in its vicinity and thus are probably caused by anisotropic foreground dust extinction in the Galactic plane. The Sgr A*(IR) complex does not exhibit any significant flux density variations at 2.2μm on time scales of minutes or years. We therefore interpret Sgr A*(IR) as a small local clustering of luminous stars (M K ≈-3) near/at the position of the compact radio source. The radial velocity dispersion of 35 early and late type stars with distances of 1 to 12″ from Sgr A* is 153±18 km/s. The new results favour the existence of a central dark mass of the order of ≈3×l06M⊙ (density ≥ 108.5 M⊙ pc-3, M/L≥10 L⊙/M⊙) within 0.14 pc of the dynamic center.

First results from the 3D near-infrared imaging array spectrometer

We present the first astronomical results from the new 3D near IR imaging array spectrometer. These include K band (1.95 to 2.45 micrometers ) spectra and images of nearby starburst galaxies and active galactic nuclei with a spectral resolution of 1000. A special image slicer allows simultaneous spectra and imaging of an 8 arc second field of view. The background limited performance achieved by this instrument represents an order of magnitude reduction in integration time over existing near IR cameras and spectrometers. In addition, subtraction of atmospheric OH lines may be performed with far higher accuracy. We discuss the data reconstruction procedure, with special emphasis on flat fielding and calibration of the detector. This is complicated by the scrambled image format, which results in adjacent image pixels being widely separated on the detector. Small non linearities of the optical elements must also be dealt with carefully. We also discuss future improvements to instrument performance, including a low order adaptive optics system for compensating atmospheric turbulence.