16 research outputs found
APECS - The Atacama Pathfinder Experiment Control System
APECS is the distributed control system of the new Atacama Pathfinder
EXperiment (APEX) telescope located on the Llano de Chajnantor at an altitude
of 5107 m in the Atacama desert in northern Chile. APECS is based on Atacama
Large Millimeter Array (ALMA) software and employs a modern, object-oriented
design using the Common Object Request Broker Architecture (CORBA) as the
middleware. New generic device interfaces simplify adding instruments to the
control system. The Python based observer command scripting language allows
using many existing software libraries and facilitates creating more complex
observing modes. A new self-descriptive raw data format (Multi-Beam FITS or
MBFITS) has been defined to store the multi-beam, multi-frequency data. APECS
provides an online pipeline for initial calibration, observer feedback and a
quick-look display. APECS is being used for regular science observations in
local and remote mode since August 2005.Comment: 4 pages, A&A, accepte
12CO(J=2->1) and CO(J=3->2) observations of Virgo Cluster spiral galaxies with the KOSMA telescope: global properties
We present 12CO(J=2->1) and CO(J=3->2) observations of quiescent Virgo
Cluster spiral galaxies with the KOSMA 3m submm telescope. The beam sizes of
80" at 345 GHz and 120" at 230 GHz are well suited for the investigation of
global properties of Virgo Cluster galaxies. The observed sample was selected
based on previous 12CO(J=1->0) detections by Stark et al. (1986), performed
with the AT&T Bell Laboratory 7m telescope (beam size 100"). We were able to
detect 18 spiral galaxies in 12CO(2->1) and 16 in 12CO(3->2). Beam matched
observations of the lowest three 12CO transitions allow us to compare our
results with previous high spatial resolution studies of (moderate) starburst
galaxies and galactic core regions. We discuss the global excitation conditions
of the ISM in these quiescent spiral galaxies. The resulting CO (3--2)/(1--0)
integrated line ratios vary over a relatively narrow range of values from 0.35
to 0.14 (on a K km/s-scale) with increasing CO (2--1)/(1--0) ratio (from 0.5 to
1.1). The line ratios between the three lowest rotational transitions of CO
cannot be fitted by any radiative transfer model with a single source
component. A two-component model, assuming a warm, dense nuclear and a cold,
less dense disc component allows us to fit the observed line ratios for most of
the galaxies individually by selecting suitable parameters. The two-component
model, however, fails to explain the observed correlation of the line ratios.
This is due to a variation of the relative filling factor of the warm gas
alone, assuming a typical set of parameters for the two components common for
all galaxies.Comment: accepted for publication in A&A, 9 pages, 8 figure
Molecular Gas in Spiral Galaxies
In this review, I highlight a number of recent surveys of molecular gas in
nearby spiral galaxies. Through such surveys, more complete observations of the
distribution and kinematics of molecular gas have become available for galaxies
with a wider range of properties (e.g., brightness, Hubble type, strength of
spiral or bar structure). These studies show the promise of both
interferometers and single-dish telescopes in advancing our general
understanding of molecular gas in spiral galaxies. In particular, I highlight
the contributions of the recent BIMA Survey of Nearby Galaxies (SONG).Comment: 8 pages, 1 figure. To appear in the proceedings of the 4th
Cologne-Bonn-Zermatt-Symposium, "The Dense Interstellar Medium in Galaxies",
which was held in Zermatt, Switzerland in September 200