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