Related papers: The thermally-unstable warm neutral medium: key fo…

We have detected HI 21cm line absorption by the Warm Neutral Medium (WNM) using the Westerbork Synthesis Radio Telescope. The absorption was detected toward Cygnus A at LSR velocities of -40 and -70 km s^{-1}. These two velocity ranges were…

We present 21-cm Spectral Line Observations of Neutral Gas with the VLA (21-SPONGE), a Karl G. Jansky Very Large Array (VLA) large project (~600 hours) for measuring the physical properties of Galactic neutral hydrogen (HI). 21-SPONGE is…

We report high spectral resolution Australia Telescope Compact Array HI 21 cm observations resulting in the detection of the warm neutral medium (WNM) of the Galaxy in absorption against two extragalactic radio sources, PKS 1814-637 and PKS…

We present methods and results from "21-cm Spectral Line Observations of Neutral Gas with the EVLA" (21-SPONGE), a large survey for Galactic neutral hydrogen (HI) absorption with the Karl G. Jansky Very Large Array (VLA). With the upgraded…

We use the Karl G. Jansky Very Large Array (VLA) to conduct a high-sensitivity survey of neutral hydrogen (HI) absorption in the Milky Way. In combination with corresponding HI emission spectra obtained mostly with the Arecibo Observatory,…

We use the Gaussian-fit results of Paper I to investigate the properties of interstellar HI in the Solar neighborhood. The Warm and Cold Neutral Media (WNM and CNM) are physically distinct components. The CNM spin temperature histogram…

We have recently completed the analysis of a survey of the HI line in emission/absorption against 79 radio sources. Our CNM temperatures are about half those of previous authors and we find a substantial quantity of thermally unstable WNM.…

We discuss physical conditions in Galactic neutral hydrogen based on deep, high velocity resolution interferometric HI 21 cm absorption spectroscopy towards 33 compact extra-galactic radio sources. The HI 21 cm optical depth spectra have…

We present sensitive Giant Metrewave Radio Telescope (GMRT) and high-resolution Arecibo HI 21-cm observations of the damped Lyman-$\alpha$ absorber (DLA) at $z=0.2212$ towards OI 363. The spectra are in excellent agreement and yield a spin…

Atomic Hydrogen-21 cm transition (HI) is an excellent tracer to study and understand the properties of the atomic gas in the Galaxy. Using the Westerbork Synthesis Radio Telescope (WSRT), we observed 12 quasar sightlines to detect galactic…

We present measurements of the H I spin temperatures (T_s) of the Cold Neutral Medium (CNM) towards radio sources that are closely aligned with stars for which published H_2 ortho-para temperatures (T_{01}) are available from UV…

We review the theory of measuring spectral lines in emission/absorption observations and apply it to a new survey of the 21-cm line against 79 continuum sources. We develop an observing technique and least-squares procedure to determine the…

We present the results of a blind search for intervening HI 21 cm absorption toward 260 radio sources in the redshift range 0<z<2.74 with the Green Bank Telescope. The survey has the sensitivity to detect sub-damped Lyman-alpha (DLA)…

We report Arecibo 21 cm absorption-emission observations to characterise the physical properties of neutral hydrogen (HI) in the proximity of five giant molecular clouds (GMCs): Taurus, California, Rosette, Mon OB1, and NGC 2264. Strong HI…

We have carried out deep, high velocity resolution, interferometric Galactic HI 21 cm absorption spectroscopy towards 32 compact extra-galactic radio sources with the Giant Metrewave Radio Telescope (GMRT) and the Westerbork Synthesis Radio…

We report a deep Giant Metrewave Radio Telescope (GMRT) search for Galactic H{\sc i} 21cm absorption towards the quasar B0438$-$436, yielding the detection of wide, weak H{\sc i} 21cm absorption, with a velocity-integrated H{\sc i} 21cm…

Radio spectroscopy at 323 MHz using the Arecibo Telescope and the VLA has produced a tentative detection of the 21cm line of neutral hydrogen at Z_abs=3.38716+-0.00007 in absorption against the radio continuum of the QSO MG0201+113 (Z_em =…

We present an X-ray absorption line spectroscopic study of the large-scale hot interstellar medium (HISM) in the Galaxy. We detect Ne IX K$_\alpha$ absorption lines in the {\sl Chandra} grating spectra of seven Galactic low-mass X-ray…

We use the millennium Arecibo 21 cm absorption-line survey measurements to examine the issue of the non-thermal contribution to the observed Galactic HI line widths. If we assume a simple, constant pressure model for the HI in the Galaxy,…

Using the Westerbork Synthesis Radio Telescope, we have detected HI 21 cm-line absorption in the Warm Neutral Medium of the Galaxy toward the extragalactic source 3C147. This absorption, at an LSR velocity of -29+/-4 km/s with a full width…