
Saha and Beginings of UV Astronomy
About eighty years back H,
Oberth pointed out the advantages of observations from space, namely
the availability of the entire electromagnetic spectrum for
observations of sources as well as observations free of the earth's
atmospheric blurring effects. As Savage (1999) comments 'At that time,
no professional astronomer took these ideas seriously. Over subsequent
20 years the only other published speculations about observatories in
space appear in the science fiction literature'. However one
astrophysicist who emphasized the importance of UV astronomy way back
in 1937 is Megh Nath Saha. In a lecture given at Harvard Observatory,
published in Harvard Observatory Bulletins, 905, 1937, he states lBut
access even to these limited regions (i.e. 2000A - 3200A) will result
in invaluable additions to our knowledge for they will afford
information about the behavior of the resonance lines of most of the
elements which occur in the Fraunhofer spectrum and thus ease our way
for the final solution of the mysteries of solar physics: e.g. we
expect to get, a) about L alpha 1216 of H, b) about 1640, A1215 of He+',
c) about existence or otherwise of the Li continuum at about 2300, d)
about the resonance lines of elements from Be to O ..., e) As regards
Mg we shall obtain much desired information about the resonance lines
of Mg and Mg+ which are just beyond 2900, f) the same is
true of resonance lines of Al to S, g) We hope to also obtain very
valuable information regarding transitional elements particularly Fe+.
The above short account will indicate how much we should
gain from a Statosphere observatory.'
It would be nice to see UVIT as an attempt tc ful~fill
Sana's vision.of a space observatory for UV astronomy as part of Indian
Multi Wavelength astronomy satellite ASTROSAT.