27-29 September 2006

Indian Institute of Astrophysics


I would like to welcome you all to the workshop on "UV and Multi wavelength Astronomy with ASTROSAT'. This workshop is planned to highlight the UV Astronomy along with other things. At this junction I would like to bring to your attention few historical remarks regarding the beginning of UV Astronomy.


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.