Back to AIfA Hi Surveys Server
This interface allows you to extract HI profiles from the EBHIS and GASS surveys and from the HI4PI Gaussian database. The profiles are generated on the fly using a weighted interpolation with a Gaussian kernel.
The effective beamsize includes telescope beam and beam smearing due to interpolation. The beam for the GASS is 14.5 arcmin (64m Parkes telescope), for EBHIS it is 10.8 arcmin (100m Effelsberg telescope).
Due to interpolations the minimum effective FWHM beam is 16 arcmin for the GASS, 12 armin for EBHIS. If you want to compare the calculated column densities, the FWHM needs to be taken into account. Expected uncertainties are in each case at a 2-3% level (about 1% scale uncertainty and 1% for uncertainties in the correction for stray radiation). Column densities are calculated for the defined velocity window in the range -400 < v < 400 km/s.
We compare the observed survey data with results from a Gaussian decomposition on a nside=1024 HEALPix (HPX) grid. Gaussian parameters for the nearest HEALPix position are listed at the end of the downloadable data table. The Gaussian curve in the figure (red) is the interpolation between the results for the neighboring HEALPix pixels. For Declinations > -2° EBHIS data are decomposed, otherwise GASS data. Please note that Gaussians that are considered to be artifacts are excluded automatically. In addition to Gaussian HI column densities we list below estimated H2 column densities for CO-dark molecular gas as well as the (potentially very uncertain) total H2 column densities. In case of obvious HI absorption against continuum sources these results should however be disregarded.
EBHIS is based on observations with the 100-m telescope of the MPIfR (Max-Planck-Institut für Radioastronomie) at Effelsberg. GASS was observed with the Parkes Radio Telescope as part of the Australia Telescope which is funded by the Commonwealth of Australia for operation as a National Facility managed by CSIRO.
If you use data products in your research or publications, please reference the following:
Kalberla, P. M. W., Kerp, J. and Haud, U. (2020) A&A, 639, A26, HI filaments are cold and associated with dark molecular gas, HI4PI based estimates of the local diffuse CO-dark H2
Haud, U. (2000) A&A, 364, 83 Gaussian decomposition of the Leiden/Dwingeloo survey. I. Decomposition algorithm
HI4PI Collaboration, Ben Bekhti, N., Flöer, L., et al. (2016) A&A, 594, A116 HI4PI: a full-sky H i survey based on EBHIS and GASS
Winkel, B., Kerp, J., Flöer, L., Kalberla, P. M. W., Ben Bekhti, N., Keller, R. and Lenz, D. (2016) A&A 585, A41 The Effelsberg-Bonn H i Survey: Milky Way gas
Kalberla, P.M.W. and Haud, U. (2015) A&A 578, A78 (Highlight: Gass: The Parkes Galactic All-Sky Survey. III)
Kalberla, P.M.W., McClure-Griffiths, N.M., Pisano, D. J. Calabretta, M. R., Ford, H. Alyson, Lockman, Felix J., Staveley-Smith, L., Kerp, J., Winkel, B., Murphy, T., Newton-McGee, K. (2010) A&A, 512, A14 (Highlight: Gass: The Parkes Galactic All-Sky Survey. II)
McClure-Griffiths, N. M.; Pisano, D. J.; Calabretta, M. R.; Ford, H. Alyson; Lockman, Felix J.; Staveley-Smith, L.; Kalberla, P. M. W.; Bailin, J.; Dedes, L.; Janowiecki, S , Gibson, B.K., Murpy, T., Newton-McGee, K. (2009) ApJS, 181, 398 (http://adsabs.harvard.edu/abs/2009ApJS..181..398M)
Data from the first data release are available at http://www.atnf.csiro.au/research/GASS/index.html
Webinterface created by Peter Kalberla