The APEX Telescope Large Area Survey of the Galaxy

ATLASGAL is the APEX Telescope Large Area Survey of the Galaxy, an observing programme with the LABOCA bolometer array at APEX, located at 5100 m altitude on Chajnantor, Chile. This survey mapped over 400 square degrees at 870 microns in the inner Galaxy, with a uniform sensitivity of a few solar masses at 1 kpc distance.

This project is a collaboration between the Max Planck Gesellschaft (MPG: Max Planck Institute für Radioastronomie, MPIfR Bonn, and Max Planck Institute für Astronomie, MPIA Heidelberg), the European Southern Observatory (ESO) and the Universidad de Chile. See the complete list of team members.

Quick facts

The first data for the ATLASGAL project were obtained in 2007, shortly after the successful commissioning of the Large APEX Bolometer Camera (LABOCA), an array of 295 bolometers observing in the 850 micron atmospheric window, built by the Millimeter and Submillimeter Astronmy group in the Max Planck Institut für Radioastronomie (MPIfR). This instrument is installed at the Cassegrain focus of the Atacama Pathfinder EXperiment (APEX), a 12 meter submillimeter telescope located on Chajnantor.

The maps observed in 2007 cover nearly 100 square degrees, in the Galactic longitude range -30° to +21°, over -1° to +1° in latitude. These data have been presented in a paper by Schuller et al., published in 2009 by A&A (see the list of publications).

From 2008 to 2010, a large programme has been conducted, aimed at:

covering ±60° in longitude, over ±1.5° in latitude
covering again ±40° in longitude, over ±1° in latitude, to improve the sensitivity in the innermost part of the Galactic plane

Finally, another short project was conducted in 2010, to cover:

longitude -80° to -60°, latitude -2° to +1°, which contains the last piece of activce star formation in the inner Galactic disk, in the Carina arm

The different coverages are shown in the figure below. The goal is to reach a pixel-to-pixel rms of 40 to 50 mJy/beam, which rougly corresponds to 5-sigma detection of 10²² cm^-2 column density of H₂, or 50 solar masses of dense cold gas and dust at a distance of 5 kpc.

This colour image is from IRAS data, at 12 microns (blue), 60 microns (green) and 100 microns (red). The successive coverages of the ATLASGAL data are indicated.

(click for full view...)

What next?

The last observations took place in September 2010 and the data reduction is ongoing. The rms in the final maps is in the range 40 to 60 mJy/beam in most directions.

A catalogue of about 6600 compact sources has been extracted from the longitude range -30 to 20°. This catalogue is now published (Contreras et al. 2012) and will shortly be available online, on the present web site. We plan to extract a catalog of compact sources from the full survey data in 2013.

Several follow-up studies in spectral lines have been started (e.g. NH₃ with the Effelsberg (Wienen et al. 2012) and Parkes telescopes, search for water masers with Effelsberg, and lines from many molecular species in the 3mm window with the MOPRA and IRAM 30m telescope). We intend to also include line identifications in the catalogue that will be online, together with identifications with sources seen in other surveys (IRAS, MSX, GLIMPSE, MIPSGAL, and the currently ongoing Hi-GAL survey with Herschel).