[Paper Review] The Leiden/Argentine/Bonn (LAB) Survey of Galactic HI: Final data release of the combined LDS and IAR surveys with improved stray-radiation corrections

P. M. W. Kalberla, W. B. Burton+5 more|LA Referencia (Red Federada de Repositorios Institucionales de Publicaciones Científicas)|Apr 6, 2005

Astrophysical Phenomena and ObservationsPhysics and Astronomy7 references2,177 citations

TL;DR

Final data release of the LAB survey, merging LDS and IAR HI data with refined stray-radiation corrections, yielding high-sensitivity all-sky 21-cm HI maps with broad velocity coverage.

ABSTRACT

We present the final data release of observations of lambda 21-cm emission from Galactic neutral hydrogen over the entire sky, merging the Leiden/Dwingeloo Survey (LDS: Hartmann & Burton, 1997) of the sky north of delta = -30 deg with the Instituto Argentino de Radioastronomia Survey (IAR: Arnal et al., 2000, and Bajaja et al., 2005) of the sky south of delta = -25 deg. The angular resolution of the combined material is HPBW ~ 0.6 deg. 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 eta_{MB} > 99% to achieve the same accuracy. The merged and refined material entering the LAB Survey of Galactic HI 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 HI survey to date, with the most extensive coverage both spatially and kinematically.

Motivation & Objective

• Provide a comprehensive, all-sky HI data product by merging two large surveys (LDS and IAR).
• Deliver improved stray-radiation corrected HI data to enable diverse Galactic ISM studies.
• Offer high angular resolution and wide velocity coverage for robust kinematic analyses.

Proposed method

• Merge the Leiden/Dwingeloo Survey (LDS) north of delta = -30 deg with the IAR south of delta = -25 deg to form a single all-sky dataset.
• Apply refined stray-radiation corrections at the Bonn institute to improve upon the original LDS correction.
• Provide an angular resolution of HPBW ~ 0.6 deg and velocity resolution 1.3 km/s over LSR velocities from -450 to +400 km/s.
• Characterize the rms brightness-temperature noise as 0.07–0.09 K and quantify residual wing errors typically below 20–40 mK.
• Position the LAB survey as a general resource for physical and structural studies of the Galactic interstellar medium.

Experimental results

Research questions

• RQ1 How can two major HI surveys (LDS and IAR) be combined into a seamless all-sky data product without compromising angular and spectral fidelity?
• RQ2 What improvements in stray-radiation corrections are required to achieve the stated low-noise, high-fidelity HI profiles?
• RQ3 What are the resulting data quality metrics (noise, residual errors) for the final LAB data release?

Key findings

• The LAB survey provides the most sensitive Milky Way HI data to date with broad spatial and kinematic coverage.
• Merged dataset achieves HPBW ~ 0.6 deg and velocity coverage from -450 to +400 km/s with 1.3 km/s resolution.
• RMS brightness-temperature noise of the merged data is 0.07–0.09 K.
• Residual stray-radiation correction errors in most profiles are below 20–40 mK in the wings.
• The correction refinements make a substantially more accurate all-sky HI data resource for ISM studies.