A search for diffuse bands in the circumstellar envelopes of post-AGB stars

In this work we present the results of a systematic search for diffuse bands (DBs, hereafter) in the circumstellar envelopes of a carefully selected sample of post-AGB stars. We concentrated on the analysis of 9 of the DBs most commonly found in the interstellar medium. The strength of these features is determined using high resolution optical spectroscopy and the results obtained are compared with literature data on field stars affected only by interstellar reddening. Based on the weak features observed in the subsample of post-AGB stars dominated by circumstellar reddening we conclude that the carrier(s) of these DBs must not be present in the circumstellar environment of these sources, or at least not under the excitation conditions in which DBs are formed. The conclusion is applicable to all the post-AGB stars studied, irrespective of the dominant chemistry or the spectral type of the star considered. A detailed radial velocity analysis of the features observed in individual sources confirms this result, as the Doppler shifts measured are found to be consistent with an interstellar origin.Comment: Accepted for A&

The design of a celestial navigation microcomputer with thoughts on an integrated information distribution system

This report lays the groundwork for further development of a microcomputer that provides full celestial navigation capability. The physical design specifications and design philosophy are investigated. The fix algorithm which allows determination of position without the use of H.O. Publications is implemented in the BASIC language. The application of microcomputer technology to devices of this nature brings to light the need for an information distribution system. Thoughts on a system of this purpose are presented.http://archive.org/details/designofcelestia00moorLieutenant, United States NavyLieutenant, United States NavyApproved for public release; distribution is unlimited