Photographic and photoelectric observations of Comet 1955g.

Abstract

view Abstract Citations (4) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Photographic and photoelectric observations of Comet 1955g. Miller, F. D. ; Liller, W. Abstract Comet 1955g was observed with the Curtis Schmidt telescope on 16, 19 and 20 August, 1955, using the combined objective prisms, two-color direct photography, and the photoelectric photometer on the respective nights. Direct photographs were taken on io~a-O emulsion through a Schott GG5 filter (thereby isolating the C, band at N4737 in the coma) and on ~o~a-E emulsion with a Wratten 22 filter. On these plates the head is conspicuously elongated along an axis normal to the projected heliocentric radius vector. Similar elongation of the images of the head on the spectrograms demonstrate that this is a phenomenon of the common gaseous constituents. The observations are intended primarily for study of the surface intensity distribution. We have, for the first time in our program, supplemented the photographic data by a set of 45 photoelectric scans. The agreement between the forms of isophotes obtained from the photographs with the isophotometer, and those drawn up from the photoelectric observations is entirely satisfactory. The relative intensity distributions on the sunward radius, measured photographically and photoelectrically, differ systematically by an amount corresponding to an error of 10 per cent in the correction for sky brightness applied to the photographic data. The photoelectric observations make it possible to express the surface intensity of the comet in absolute units. The variation of surface intensity on the sun- ward radius departs from the inverse-distance law predicted by the simple "fountain" model, the gradient being less at small distance, and greater at large distance, than that predicted by this law. Compared to the isophotes derived from the Io~a-O/GG5 plates, those obtained from the exposure on io~a-E/W~~ show a narrower tail, and less conspicuous coma. Similar results were obtained by Yoss in his study of Comet 19521 (Yoss 1953) and by Miller for Comet I953~ (Miller 1955). Miller, F. D. 1955, A. J. 6o, 173. Yoss, K. M. 1953, La Physique des Cometes, p. 72. University of Mfrhigan Observatory, Ann Arbor, Mich. Publication: The Astronomical Journal Pub Date: February 1956 DOI: 10.1086/107276 Bibcode: 1956AJ.....61...10M full text sources ADS |