J/A+A/585/A41 EBHIS spectra and HI column density maps (Winkel+, 2016)
The Effelsberg-Bonn HI Survey: Milky Way gas.
First data release.
Winkel B., Kerp J., Floeer L., Kalberla P.M.W., Ben Bekhti N., Keller R.,
Lenz D
<Astron. Astrophys. 585, A41 (2016)>
=2016A&A...585A..41W 2016A&A...585A..41W (SIMBAD/NED BibCode)
ADC_Keywords: Surveys ; Milky Way ; Interstellar medium ; H I data ;
Spectroscopy
Keywords: surveys - ISM: atoms - techniques: spectroscopic
Abstract:
The Effelsberg-Bonn HI Survey (EBHIS) is a new 21-cm survey performed
with the 100-m telescope at Effelsberg. It covers the whole northern
sky out to a redshift of z∼0.07 and comprises HI line emission from
the Milky Way and the Local Volume. We aim to substitute the
northern-hemisphere part of the Leiden/Argentine/Bonn Milky Way HI
survey (LAB) with this first EBHIS data release, which presents the HI
gas in the Milky Way regime. The use of a seven-beam L-band array made
it feasible to perform this all-sky survey with a 100-m class
telescope in a reasonable amount of observing time. State-of-the-art
fast-Fourier-transform spectrometers provide the necessary data
read-out speed, dynamic range, and spectral resolution to apply
software radio-frequency interference mitigation. EBHIS is corrected
for stray radiation and employs frequency-dependent flux-density
calibration and sophisticated baseline-removal techniques to ensure
the highest possible data quality. Detailed analyses of the resulting
data products show that EBHIS is not only outperforming LAB in terms
of sensitivity and angular resolution, but also matches the
intensity-scale of LAB extremely well, allowing EBHIS to be used as a
drop-in replacement for LAB. Data products are made available to the
public in a variety of forms. Most important, we provide a properly
gridded Milky Way HI column density map in HEALPix representation. To
maximize the usefulness of EBHIS data, we estimate uncertainties in
the HI column density and brightness temperature distributions,
accounting for systematic effects.
Description:
The EBHIS 1st data release comprises 21-cm neutral atomic hydrogen
data of the Milky Way (-600km/s<vlsr<+600km/s) as observed with
the 100-m radio telescope at Effelsberg. EBHIS covers the full
northern hemisphere (north of a declination of -5°).
Full spectral data is provided in two forms:
(1) Standard FITS data cubes, each having a size of about 20x20sq.deg.
For convenience, we provide three different map projections, CAR, SIN,
and SFL; see world-coordinate-system, WCS, references:
Greisen & Calabretta, 2002A&A...395.1061G 2002A&A...395.1061G
Calabretta & Greisen, 2002A&A...395.1077C 2002A&A...395.1077C
Greisen et al., 2006A&A...446..747G 2006A&A...446..747G
Note, size in longitude is 20° in absolute coordinates for
CAR projection, and true-angular size for SIN and SFL projections.
(2) FITS binary tables containing lists of spectra sampled on a
HealPIX grid (nside=1024, Galactic coordinates, Ring indexing scheme,
Gorski et al., 2005ApJ...622..759G 2005ApJ...622..759G). To make handling of the data
easier, the table is split into smaller files. Each of these contains
spectra belonging to one of the 192 base/parent pixels of the nside=4
pixelization. For convenience, the binary tables also contain EQ2000
and Galactic coordinate positions for each individual spectrum, as
well as the associated HealPIX index.
Furthermore, we provide the full northern-sky HI column density
distribution, both, in a
(1) HealPIX-grid binary table (nside=1024, Galactic coordinates, Ring
indexing scheme)
(2) Standard FITS 2D image in ZEA-projection (zenith equal area).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
nhi.dat 60 2 HI column densities fits files list
nhi/* . 2 Individual HI column densities fits files
cubes.dat 26 232 List of FITS data cubes
fits/* . 232 Individual FITS data cubes
hpxspec.dat 57 122 List of HPX-grid FITS binary tables
hpx/* . 122 Individual HPX-grid FITS binary tables
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Byte-by-byte Description of file: nhi.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 A11 --- FileName Name of the fits file in subdirectory nhi
13- 60 A48 --- Title Title of the file
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Byte-by-byte Description of file: cubes.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 F5.1 deg RAdeg Right ascension (J2000) of data cube center
7- 10 F4.1 deg DEdeg Declination (J2000) of data cube center
12- 14 A3 --- WCSproj WCS projection code
16- 26 A11 --- FileName Name of the FITS file in subdirectory fits
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Byte-by-byte Description of file: hpxspec.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 F8.4 deg GLON Galactic longitude
10- 17 F8.4 deg GLAT Galactic latitude
19- 26 F8.4 deg RAdeg Right ascension (J2000)
28- 35 F8.4 deg DEdeg Declination (J2000)
37- 41 I5 --- NumRows Number of spectra in file
43- 45 I3 --- HPXidx HealPIX index (nside=4, RING scheme,0-based)
47- 57 A11 --- FileName Name of the FITS file in subdirectory hpx
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Acknowledgements:
Benjamin Winkel, bwinkel(at)mpifr.de
(End) Benjamin Winkel [MPIfR], Patricia Vannier [CDS] 18-Nov-2015