J/other/JApA/25.143 High galactic latitude HI absorption survey (Mohan+, 2004)
A high galactic latitude HI 21 cm-line absorption survey using the GMRT.
I. Observations and spectra.
Mohan R., Dwarakanath K.S., Srinivasan G.
<J. Astrophys. Astron., 25, 143-183 (2004)>
=2004JApA...25..143M 2004JApA...25..143M
ADC_Keywords: Interstellar medium ; H I data ; Radio sources
Keywords: ISM: clouds, kinematics and dynamics - radio lines: ISM
Abstract:
We have used the Giant Meterwave Radio Telescope (GMRT) to measure the
Galactic HI 21-cm line absorption towards 102 extragalactic radio
continuum sources, located at high (|b|>15°) Galactic latitudes.
The Declination coverage of the present survey is DE~-45°. With a
mean rms optical depth of ∼0.003, this is the most sensitive Galactic
HI 21-cm line absorption survey to date. To supplement the absorption
data, we have extracted the HI 21-cm line emission profiles towards
these 102 lines of sight from the Leiden Dwingeloo Survey of Galactic
neutral hydrogen. We have carried out a Gaussian fitting analysis to
identify the discrete absorption and emission components in these
profiles. In this paper, we present the spectra and the components. A
subsequent paper will discuss the interpretation of these results.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
appena.dat 59 102 List of sources observed with the GMRT
appenc.dat 103 466 *Discrete HI features
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Note on appenc.dat : List of the discrete HI features identified from
the high latitude Galactic HI absorption survey using the GMRT and
from the HI emission data along the respective lines of sight from
the Leiden-Dwingeloo survey (LDS) of Galactic.
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See also:
VIII/54 : Atlas of Galactic Neutral Hydrogen (Hartmann+, 1997)
Byte-by-byte Description of file: appena.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Source Source designation (JHHMM-DDd)
11- 12 I2 h RAh Right ascension (J2000)
14- 15 I2 min RAm Right ascension (J2000)
17- 21 F5.2 s RAs Right ascension (J2000)
23 A1 --- DE- Declination sign (J2000)
24- 25 I2 deg DEd Declination (J2000)
27- 28 I2 arcmin DEm Declination (J2000)
30- 33 F4.1 arcsec DEs Declination (J2000)
35- 40 F6.2 deg GLON Galactic longitude
42- 47 F6.2 deg GLAT Galactic latitude
49- 53 F5.3 --- taurms rms optical depth in the HI absorption spectra
55- 59 F5.2 Jy S1420MHz Observed flux-density, at 1420.4MHz
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Byte-by-byte Description of file: appenc.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Source Name of the background source (1)
12 A1 --- l_tauHI Limit flag on tauHI (for optical depth limit
obtained from the HI absorption profiles
along the respective directions
13- 17 F5.3 --- tauHI ? HI absorption peak optical depth (GMRT)
or HI absorption optical depth limit
if l_tauHI = "<"
19- 22 F4.3 --- e_tauHI ? rms uncertainty on tauHI
24- 30 F7.3 km/s VlsrA ? HI absorption LSR velocity (GMRT) (2)
32- 36 F5.3 km/s e_VlsrA ? rms uncertainty on VlsrA
39- 43 F5.2 km/s FWHMA ? HI absorption mean FWHM (GMRT) (2)(3)
44- 47 F4.2 km/s e_FWHMA ? rms uncertainty on FWHMA
49- 54 F6.3 K TB ? HI emission brightness temperature (LDS)
56- 60 F5.3 K e_TB ? rms uncertainty on TB
62- 69 F8.3 km/s VlsrE ? HI emission LSR velocity (LDS) (4)
71- 76 F6.3 km/s e_VlsrE ? rms uncertainty on VlsrE
78- 83 F6.2 km/s FWHME ? HI emission mean FWHM (LDS) (4)
85- 89 F5.2 km/s e_FWHME ? rms uncertainty on FWHME
91 A1 --- l_TS Limit flag on TS
92- 95 I4 K TS ? Spin temperature of the absorbing gas (5)
97-103 A7 --- Note [No data] No data from LDS
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Note (1): Background source, towards which the absorption was measured
using the GMRT.
Note (2): Mean LSR velocity and the FWHM of discrete components identified
using Gaussian fitting.
Note (3): The value of FWHM is deconvolved for a channel width of 3.26km/s.
The unresolved lines are marked with a "-" .
Note (4): Value of deconvolved HI emission profile along the same line of
sight, obtained from the Leiden-Dwingeloo Survey of Galactic
neutral hydrogen (Hartman & Burton, 1995, LDS Cat. VIII/54)
Note (5): Spin temperature, calculated using the absorption and emission data.
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 12-Jun-2006