THE SOLAR MG-I SPECTRUM FROM ATMOS .1. IDENTIFICATION AND PRELIMINARY DISCUSSION

As an initial step in a program to understand some puzzling aspects of the infrared solar Mg I spectrum we have examined the set of high-resolution, high signal-to-noise ratio, lines of this spectrum obtained in the 1985 ATMOS experiment on Spacelab 3. From laboratory data, supplemented by theoretical expressions, wave-numbers were obtained for the Mg I transitions lying in or near the range covered by ATMOS, namely 650 to 4800 cm-1 (2.3-16-mu-m). Lines involving principal quantum numbers up to n = 10 are seen in the data; we describe some striking features of the Mg i spectrum and indicate some directions of interest for future analytical studies and for future flights of the experiment.