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Showing posts from July, 2020

Planning the Celebration of 70th Anniversary of Detection of Neutral Hydrogen (21 cm line)

Greetings, In the summer of 2019, I had proposed a 70th anniversary celebration of the detection of neutral hydrogen that my father was involved in. Dr. Harold I Ewen’s (“Doc Ewen”) 1951 PhD thesis, “Radiation from Galactic Hydrogen at 1420 Megacycles per Second,” reported on the first detection of a spectral line in radio astronomy. His advisor at Harvard University was Dr. Edward M. Purcell.    The horn antenna used for detection at the Lyman Laboratory of Harvard University is now displayed in front of the Jansky Lab at NRAO in Green Bank, West Virginia . As I followed up in May 2020 as planned to prepare for the 2021 festivities, the world had already been immersed in the COVID-19 Pandemic .   All industries were shutting down and quarantine requirements were implemented.    The original plan to build and launch a 2021 celebration of the 1951 achievement had to be shelved. The PAASE Institute was developed to satisfy the need As the PAASE Institute gets ready to celebrate the 70

Harvard University Detection of galactic hydrogen in 1951 with Ewen

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   Dr. Harold I. Ewen ("Doc Ewen"), working with Dr. Edward M. Purcell at Harvard in 1951, detected radiation from galactic hydrogen at 1420 Mc/sec. From 1952-1958 he was Co-Director of the Harvard Radio Astronomy Program; during that time he was a member of the committees that recommended establishment by the National Science Foundation of a national facility for radio astronomy, and also recommended Green Bank WV as the best site for what became National Radio Astronomy Observatory.  The hydrogen line, 21-centimeter line is the electromagnetic radiation spectral line that is created by a change in the energy state of neutral hydrogen atoms. This electromagnetic radiation is at the precise frequency of 1,420,405,751.7667±0.0009 Hz which is equivalent to the vacuum wavelength of 21.1061140542 cm in free space. This wavelength falls within the microwave region of the electromagnetic spectrum, and it is observed frequently in radio astronomy, since those radio waves can penetra