Astronomy Literature Research Articles

Density Estimation With Confidence Sets Exemplified by Superclusters and Voids in the Galaxies

Abstract A method is presented for forming both a point estimate and a confidence set of semiparametric densities. The final product is a three-dimensional figure that displays a selection of density estimates for a plausible range of smoothing parameters. The boundaries of the smoothing parameter are determined by a nonparametric goodness-of-fit test that is based on the sample spacings. For each value of the smoothing parameter our estimator is selected by choosing the normal mixture that maximizes a function of the sample spacings. A point estimate is selected from this confidence set by using the method of cross-validation. An algorithm to find the mixing distribution that maximizes the spacings functional is presented. These methods are illustrated with a data set from the astronomy literature. The measurements are velocities at which galaxies in the Corona Borealis region are moving away from our galaxy. If the galaxies are clustered, the velocity density will be multimodal, with clusters corresponding to modes. Natural candidates for examining the distribution of the data are finite normal mixtures and histograms. The shortcomings of these methods become apparent from the analysis of these data. By finding a confidence set of densities a set of estimates is obtained, ranging from smooth to rough; the number of modes ranges from three to seven. The confidence set of densities is further substantiated by performing nonparametric tests for the number of modes.

State of the Art Survey of Reference Materials in Physics and Astronomy

The most general English‐language indexing tool for the literature of physics and astronomy is Physics Abstracts (Science Abstracts, Section A). It aims at worldwide coverage of the physics literature. Emphasis is on physics publications in serial or book form; only selective coverage of technical reports and of astronomical literature is given. Under the name of INSPEC it can be used in computer searches (see below for review of INSPEC concordance).

Evaluation of current awareness service for physics and astronomy literature

AbstractAn evaluation of a current awareness service in Physics and Astronomy at The University of Texas at Austin is presented. The service is provided currently to over 130 physicists and astronomers; about half of them participated in the evaluation. The computer‐produced printouts were derived from the monthly SPIN tapes of the American Institute of Physics. It was found that 67% rated the current awareness printouts favorably and 20% unfavorably. Participants tended to use SPIN to supplement their usual literature needs. The primary complaints about the effectiveness of the service were the broadness of the classification scheme, insufficient journal coverage, and slowness in receipt of abstracts on the tapes. A retrospective search facility is available but not heavily used at the present time, due to the short time span covered by the tapes.

Conrad Vernon Morton (1905-1972)

Conrad Vernon Morton, named Walter Vernon Morton at the time of his birth on October 24, 1905, was the son of Walter Crow Morton and Nioma (later Noma) Bartholomew Morton. He was born in Fresno, California, where his parents had been life-long residents and his father had a roofing and building contractor's business. Walter Crow Morton died when Walter was still young, and in about 1917 his mother married Alva B. McCray, who also had been a resident of Fresno for many years. In fact, the McCray and Bartholomew families were friends. Mr. McCray was employed by the Santa Fe Railroad. The family home at Fresno included a vineyard and various gardens on the property, and so young Walter was introduced to plants at an early age. As a child, he planted and tended a small garden of his own. His mother was well known in the area for her rose garden; she grew about 130 varieties abundantly. During his junior high and high school years, the family lived in Berkeley, where Mrs. McCray's sister and family lived. The climate there was more moderate than in Fresno, and better for Mrs. McCray's health. When he was in high school Walter won a fellowship to the local Art Institute. Of all the students in the class, he was the only boy, and for this reason he did not pursue his study of art very far at that time. (After he began his professional career, however, he studied both painting and the piano diligently, and mastered and practiced both arts with great pleasure for himself and his friends for the remainder of his life. He was also greatly interested in the history of the cinema, in dramatics, and in philately. For a more ample account of Morton's non-botanical interests, see Ewan, J. A. 1973. Taxon 22: 271-274.) Morton entered the University of California at Berkeley in 1924. At that time he changed his given names to Conrad Vernon (the legal change was made on April 14, 1926). His interests at first included the physical sciences, mathematics, astronomy, and slavic languages and literature. During the latter part of his freshman year he began a course in general botany. In his sophomore year he studied elementary taxonomy under Prof. Willis L. Jepson. Apparently this course triggered a strong interest in taxonomic botany, for he took several more courses from Jepson, plus algology and mycology from Prof. Gardner, plant physiology from Prof. Holman, and cytology and genetics from Prof. Goodspeed. His first botanical collections were made around Berkeley in January 1926. Morton held tuition scholarships at the University for the last three of his undergraduate years. He was a Levi Strauss Scholar in 1925-26, a Henry Morgan Holbrook Scholar in 1926-27, and a Carrie M. Jones Scholar in 1927-28. He was elected to membership in the scientific fraternity Sigma Xi and in the biological sciences fraternity Phi Sigma. In October 1926 he was inducted into

Radiative Transfer in Dispersive Media

A radiative transfer equation is derived which is sufficiently general to apply to energy transfer by various types of wave motion, such as electromagnetic waves, sound waves, hydromagnetic waves, etc. Scattering of waves is neglected. The equation is compared to the equation found in the literature of radio astronomy, and the meaning of a term in this equation is clarified. The general solution of the equation is given. A more rigorous derivation of the transfer equation based on a method due to Wigner is given.

Our Astronomical Column

AN ANCIENT “URANOMETRIA.”—We have received a very interesting work, published by Dr. Schjellerup, of the Observatory of Copenhagen, under the auspices of the Imperial Academy of Sciences of St. Petersburg. It contains a description of the constellations, with the star magnitudes, composed in the middle of the tenth century by the Persian astronomer, Abd-al-Rahman al-Sûfi, and is a literal translation of two Arabic manuscripts preserved in the Royal and Imperial libraries of Copenhagen and St. Petersburg. A more particular account of the valuable addition which Dr. Schjellerup has made to the literature of astronomy will be given in this column next week. Meanwhile, we may just note one curious statement made by the Persian astronomer with reference to the well-known variable star Algol, viz., that at the time of his observations the star was reddish—a characteristic applied also to Antares, Aldebaran, a Hydræ, and a few other stars, which are also reddish in our own day; but at present there is no tinge of colour about Algol, which may be fairly described as a white star, and if there be one of its class more than another in which the periodical fluctuation of light can with much appearance of probability be attributed to the intervention of a revolving attendant; passing regularly in our line of sight, it is to this star that we might point in illustration. Its former ruddy light, however, rather necessitates a different explanation, and one which, notwithstanding the comparative regularity of its changes, may perhaps assimilate it to the more numerous class of variable stars.