J/ApJS/105/369 Galactic H I column densities (Murphy+ 1996)
Galactic H I column densities toward quasars and active galactic nuclei
Murphy E.M., Lockman F.J., Laor A., Elvis M.
<Astrophys. J. Suppl. Ser. 105, 369 (1996)>
=1996ApJS..105..369M 1996ApJS..105..369M
ADC_Keywords: QSOs ; Active gal. nuclei ; H I data
Keywords: Galaxy: structure - radio lines: ISM - X-rays: general
Abstract:
We have determined accurate values of the Galactic neutral hydrogen
column density, NH, toward 220 quasars and active galactic nuclei
from 21cm H I measurements made on the 130 Foot Telescope (42.7m).
Accurate values of NH have now been obtained for the whole PG bright
quasar sample and most quasars that have been observed by ROSAT and
the Hubble Space Telescope through mid-1993. The spectra were
corrected for stray 21cm radiation yielding values of NH with a
typical uncertainty of 1x1019cm-2 for high Galactic latitude
directions. The H I column densities will be useful for correcting for
interstellar opacity at UV and soft X-ray wavelengths, and for
estimating the reddening and extinction toward these objects.
Description:
The file data.fit contains the data for all 220 objects as FITS IMAGE
extensions. The spectrum for each object is written as an image
extension in the same order as printed in table 1 (and the FITS table
in the first file). The data are written as 1-dimensional spectra and
are in units of brightness temperature in Kelvins.
In the header, the LSR velocity (CRVAL1), the reference pixel
(CRPIX1), and the velocity increment (CRPIX1) can by used to calculate
the LSR velocity of a given pixel. Note that the data are linear in
frequency, not velocity, and this must be taken into account when
calculating the velocity of a given pixel.
The FITS files were written using the CFITSIO package written by Dr.
William Pence at the GSFC.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 66 220 Summary of 21 cm H I observations
data.fit 2880 441 FITS IMAGE Extension file of spectra
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Byte-per-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- Object Object name
18- 24 F7.3 deg RAdeg Right ascension, 1950
26- 32 F7.3 deg DEdeg Declination, 1950
34- 40 F7.3 deg GLon Galactic longitude
42- 48 F7.3 deg GLat Galactic latitude
50- 54 F5.1 cm-2 NH_Thin Optically thin H I column density
56- 60 F5.1 cm-2 NH_TS150 Uniform temp 150 K H I column density
62 I1 --- Comment *Comment number
64- 66 I3 --- Image *Image extension number
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Note on Comment:
1) Data not corrected for stray radiation
2) The listed value of NH includes emission only between LSR
velocities -60km/s and +28km/s. The H I in NGC 247 itself
appears in the spectrum at V_LSR>+28km/s.
Note on Image:
The image extension number of the data for each object in the
data file, data.fit.
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Origin: AAS CD-ROM series, Volume 7, 1996 Lee Brotzman [ADS] 22-Oct-96
(End) [CDS] 03-Feb-1997