Observation of a Line in the Galactic Radio Spectrum: Radiation from Galactic Hydrogen at 1,420 Mc./sec.

  title={Observation of a Line in the Galactic Radio Spectrum: Radiation from Galactic Hydrogen at 1,420 Mc./sec.},
  author={Harold I. Ewen and Edward M. Purcell},
Spectral Lines in Radio Astronomy
A review of the elements of microwave spectroscopy as it concerns, or is likely to concern, radio astronomy is presented. This review attempts to show how atomic and molecular resonance lines ariseExpand
Tuning in to the cosmic dawn
In 1951, three separate research groups established radio astronomy as a contender to the dominance of optical astronomy. Using the interstellar 21-cm line, they provided a method to look deeper intoExpand
Astronomy: Dark arc casts a long shadow
The interstellar medium is mainly hydrogen gas, which is thought to cool to form clouds of molecular hydrogen. But the discovery of a large cloud of cold atomic hydrogen overturns that belief.
The Galactic Center: Is It a Massive Black Hole?
  • K. Lo
  • Physics, Medicine
  • Science
  • 1986
Observations reviewed here suggest unusual activity and the possible existence of a massive black hole in the nucleus of the authors' galaxy. Expand
This is an introduction to the following seven papers, which are expanded versions of talks presented to the Historical Astronomy Division of the American Astronomical Society at its January 2010Expand
Observational Radio Astronomy
Publisher Summary In order to present the over-all pattern of radio astronomy this chapter discusses the main results concerning the Sun, the Milky Way, and external galaxies. It deals with theExpand
The search for the elusive Zeeman effect in HI
The paper describes the early endeavours by radioastronomers to detect the weak signature of the Zeeman effect in interstellar neutral hydrogen clouds in an effort to measure the Galactic magneticExpand
The Cool ISM in Galaxies
This chapter describes the different constituents of the observable interstellar medium (ISM) in galaxies and reviews the relationships between the ISM and the star formation in galaxies. TheExpand
Future Possibilities for Detecting HI at High Redshift
The 21-cm line of neutral hydrogen is in many respects the most valuable tracer of neutral gaseous mass in astrophysics. Even though neutral gas becomes predominantly molecular at high densities, theExpand
An Introduction to Radio Astronomy
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A broad-band microwave noise source
  • W. Mumford
  • Mathematics, Computer Science
  • Bell Syst. Tech. J.
  • 1949
Measurements of the microwave noise power available from gaseous discharges, such as in an ordinary fluorescent lamp, show remarkable uniformity and stability, and are suitable for a new type of standard noise source. Expand
Frequency Variation of the Intensity of Cosmic Radio Noise
THE intensity of cosmic radio noise (as received on horizontal half-wave dipole antennæ one quarter wave-length above ground) has been measured at 25 Mc. and 110 Mc. by H. V. Cottony, W. Q. Crichlow,Expand
Hyperfine structure of hydrogen and deuterium
A new determination of the hyperfine structure separation of both hydrogen and deuterium in the (2)S(sub 1/2) state has been made by the atomic beam method. The new values are, for several reasons,Expand