Electronic Telegram No. 21 Central Bureau for Astronomical Telegrams INTERNATIONAL ASTRONOMICAL UNION M.S. 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A. IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions) CBAT@CFA.HARVARD.EDU (science) URL http://cfa-www.harvard.edu/iau/cbat.html eta CARINAE Z. Abraham and T. P. Dominici, Sao Paulo University and Sao Paulo State Research Foundation, report that radio measurements at 7 mm, made at the Itapetinga Radio Observatory, show that the flux density decreased from 3 Jy on May 22 to 1.5 Jy on June 20, remaining constant since then. A. Damineli, N. Leister, and R. Levenhagen report that spectroscopy, obtained at the Pico dos Dias Observatory, shows the complete disappearance of the [Ne III] 386.8-nm spectral line on June 23. Both results indicate that eta Car has entered the deepest phase of the 2003.5 event, as predicted by Damineli et al. (2000, Ap.J. 528, L101). NOTE: These 'Central Bureau Electronic Telegrams' are intended to be preliminary announcements of items that later appear in the formal IAU Circulars. Citations should normally be made to IAUCs rather than to CBETs. (C) Copyright 2003 CBAT 2003 June 26 (CBET 21) Kyle E. Smalley