Fig. 1: H i emission integrated over the velocity range −400 < v < +400 km s−1 in the LAB dataset, shown in Aitoff projection. The Galactic centre is in the middle. The integrated emission (0 < NH < 2·1022 cm−2, logarithmic scale) yields column densities under the assumption of optical transparency; this assumption may be violated at latitudes within about 10° of the Galactic equator.
The LAB survey contains the final data release of observations of λ21-cm emission from Galactic neutral hydrogen over the entire sky, merging the Leiden/Dwingeloo Survey (LDS: Hartmann & Burton 1997) of the sky north of δ = −30° with the Instituto Argentino de Radioastronomía Survey (IAR: Arnal et al. 2000 and Bajaja et al. 2005) of the sky south of δ = −25°. The angular resolution of the combined material is HPBW ~ 0.6°. The LSR velocity coverage spans the interval −450 km/s to +400 km/s, at a resolution of 1.3 km/s. The data were corrected for stray radiation at the Institute for Radioastronomy of the University of Bonn, refining the original correction applied to the LDS. The rms brightness-temperature noise of the merged database is 0.07 – 0.09 K. Residual errors in the profile wings due to defects in the correction for stray radiation are for most of the data below a level of 20 – 40 mK. It would be necessary to construct a telescope with a main beam efficiency of ηMB > 99% to achieve the same accuracy. The merged and refined material entering the LAB Survey of Galactic H i is intended to be a general resource useful to a wide range of studies of the physical and structural characteristices of the Galactic interstellar environment. The LAB Survey is the most sensitive Milky Way H i survey to date, with the most extensive coverage both spatially and kinematically.
Additional information about the LAB Survey can be found in the corresponding press release (in German only).
With the form on this page you can extract the H i column density and the complete spectrum for any position on the sky from the LAB Survey. Please specify below the desired position in either equatorial or Galactic coordinates. For additional help please click on the corresponding labels next to the fields.
The online access tool does not allow to automatically process a large number of positions. For this purpose you can download the entire LAB survey from the CDS server in Strasbourg. At ftp://cdsarc.u-strasbg.fr/pub/cats/VIII/76 different versions of the survey are available as FITS data files via FTP. Details about the individual data cubes can be found in the ReadMe file.
Below you will find two videos showing a sweep in velocity through the data cube of the LAB survey from −400 to +400 km/s. The first video is presented in the Galactic centre projection, the second one in the anti-centre projection. Both files are large (about 8 MB)!
Sweep through the data cube,
Galactic centre projection (MPEG video, 7.8 MB)
Sweep through the data cube, Galactic anti-centre projection (MPEG video, 8.3 MB)
When refering to the LAB survey, please use the following reference:
Depending on the region of the sky being studied, please cite, in addition to the Kalberla et al. (2005) reference, also the appropriate source of the material used:
Observers were Dap Hartmann and W.B. Burton (Leiden University) for the Dwingeloo telescope, and E.M. Arnal, E. Bajaja, J.J. Larrarte, R. Morras, and W.G.L. Pöppel (Argentine Institute for Radio Astronomy) for the Villa Elisa telescope. Correction for stray radiation and combination of the data by P.M.W. Kalberla (Bonn University).
Web interface: Tobias Westmeier, Bonn University