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
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:
FileName Lrecl Records Explanations
ReadMe 80 . This file appena.dat 59 102 List of sources observed with the GMRT appenc.dat 103 466 *Discrete HI features
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.
See also: VIII/54 : Atlas of Galactic Neutral Hydrogen (Hartmann+, 1997) Byte-by-byte Description of file: appena.dat
Bytes Format Units Label Explanations
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
Byte-by-byte Description of file: appenc.dat
Bytes Format Units Label Explanations
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
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.
History: From electronic version of the journal
(End) Patricia Vannier [CDS] 12-Jun-2006
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