Author name code: roberts-walter-orr ADS astronomy entries on 2022-09-14 =author:"Roberts, W.O." OR =author:"Roberts, Walter Orr" ------------------------------------------------------------------------ Title: Space Phoenix Authors: Ware, Randolph H.; Rogers, Thomas F.; Padua, David J.; Roberts, Walter Orr Bibcode: 1988SpPol...4..143W Altcode: The US federal government is collaborating with a non-profit university consortium and its commercial project managers to develop the Space Shuttle fleet's expended external fuel tanks for scientific and commercial uses in space. Nearly a half dozen years in evolution, the Space Phoenix Program is a private-sector civil space programme with the long-term goal of opening the Earth's space to as many people, organizations and activities as possible, as soon as possible, and at the lowest cost to them as possible. In time it is expected to be a major focus for private-sector activities in space. This report describes how it will work. Title: On the Apparent Modulation of Thunderstorms by Solar Plages Authors: Olson, R. H.; Roberts, W. O. Bibcode: 1983wcrs.proc..469O Altcode: No abstract at ADS Title: Panel Discussion: The Reality of the Association Between Solar Activity (Such as Flares) and Atmospheric Electrical Effects (Including Thunderstorms) Authors: Roberts, W. O. Bibcode: 1983wcrs.proc..495R Altcode: No abstract at ADS Title: A Suggested Approach to Research on the Sun / Weather Problems Authors: Roberts, W. O.; Olson, R. H. Bibcode: 1982coas.conf..161R Altcode: 1982cia..conf..161R No abstract at ADS Title: Interplanetary Magnetic Field Polarity and the Size of Low-Pressure Troughs Near 180 degrees W Longitude Authors: Wilcox, J. M.; Duffy, P. B.; Schatten, K. H.; Svalgaard, L.; Scherrer, P. H.; Roberts, W. O.; Olson, R. H. Bibcode: 1979Sci...204...60W Altcode: When the interplanetary magnetic field is directed away from the sun, the area of wintertime low-pressure (300-millibar) troughs near 180 degrees W longitude is significantly larger than when the field is toward the sun. This relation persists during most of the winters of 1951 to 1973. Title: Introductory Review of Solar-Terrestrial Weather and Climate Relationships Authors: Roberts, W. O. Bibcode: 1979stiw.conf...29R Altcode: No abstract at ADS Title: Solar plages and the vorticity of the earth's atmosphere Authors: Olson, R. H.; Roberts, W. O.; Prince, H. D.; Hedeman, E. R. Bibcode: 1978Natur.274..140O Altcode: Three superimposed epoch analyses of the vorticity area index (VAI) at 500 mbar are described. The analyses used the following definitions of the zero days: (1) the central meridian passage (CMP) of very active solar plages; (2) the occurrence of peak values of the 10.7 cm solar radio flux; and (3) the CMP of active solar plages also accompanied at CMP by sharp rises in 10.7 cm solar radio noise. All three superimposed epoch analyses show a sustained rise in VAI several days before the zero day; the rise continues through the zero day and is followed by a sustained minimum in VAI several days after the zero day. The results suggest that the location of the very active plages play an important role in determining their meteorological influence. It is possible that the initial rise in VAI is caused by enhanced electromagnetic radiation associated with the solar activity, and that the decrease some days later is the result of the geomagnetic storm particle emission that generally follows the zero date. Title: Analysis of a possible Sun-weather correlation Authors: Gerety, Edward J.; Olson, Roger H.; Roberts, Walter Orr Bibcode: 1978Natur.272..231G Altcode: XANTHAKIS1 has reported a striking, if complex, relationship between solar activity and Northern Hemisphere precipitation. This resulted in a strong negative correlation between rainfall and solar activity found in the latitude belt of 60° to 70°N. Other belts showed pronounced positive correlations, or a change from negative to positive correlation. We decided that these correlations needed a totally independent confirmation2, and so we repeated the analysis, using a more extensive data base. Xanthakis has since published a more extensive survey of global precipitation and solar activity3. This also contains detailed information on his methods of analysis, and extends the study to the Southern Hemisphere, where further verification of the association is claimed. Our studies reported here also encompassed both hemispheres and our results show only a general similarity with those of Xanthakis. Title: The Influence of Solar Proton Flares on the Circulation of the Earth's Troposphere (Abstract) Authors: Olson, R. H.; Roberts, W. O.; Shea, M. A.; Smart, D. F. Bibcode: 1977ICRC....5..245O Altcode: 1977ICRC...15e.245O No abstract at ADS Title: Short term relationships between solar flares, geomagnetic storms, and tropospheric vorticity patterns Authors: Olson, R. H.; Roberts, W. O.; Zerefos, C. S. Bibcode: 1975Natur.257..113O Altcode: No abstract at ADS Title: Relationships Between Solar Activity and Climate Change Authors: Roberts, Walter Orr Bibcode: 1975NASSP.366...13R Altcode: 1975prbs.conf...13R No abstract at ADS Title: Influence of Solar Magnetic Sector Structure on Terrestrial Atmospheric Vorticity. Authors: Wilcox, John M.; Scherrer, Philip H.; Svalgaard, Leif; Roberts, Walter Orr; Olson, Roger H.; Jenne, Roy L. Bibcode: 1974JAtS...31..581W Altcode: The solar magnetic sector structure has a sizable and reproducible influence on tropospheric and lower stratospheric vorticity. The average vorticity during winter in the Northern Hemisphere north of 2ON latitude reaches a minimum approximately one day after the passing of a sector boundary, and then increases during the following two or three days. The effect is found at all heights within the troposphere, but is not prominent in the stratosphere, except at the lower levels. No single longitudinal interval appears to dominate the effect. Title: C. G. Abbot, 1872 May 31 - 1973 December 17 Authors: Roberts, W. O. Bibcode: 1974PhT....27e..65R Altcode: No abstract at ADS Title: Solar Magnetic Sector Structure: Relation to Circulation of the Earth's Atmosphere Authors: Wilcox, John M.; Scherrer, Philip H.; Svalgaard, Leif; Roberts, Walter Orr; Olson, Roger H. Bibcode: 1973Sci...180..185W Altcode: The solar magnetic sector structure appears to be related to the average area of high positive vorticity centers (low-pressure troughs) observed during winter in the Northern Hemisphere at the 300-millibar level. The average area of high vorticity decreases (low-pressure troughs become less intense) during a few days near the times at which sector boundaries are carried past the earth by the solar wind. The amplitude of the effect is about 10 percent. Title: New evidence for effects of variable solar corpuscular emission on the weather. Authors: Roberts, W. O.; Olson, R. H. Bibcode: 1973RvGSP..11..731R Altcode: 1973RvGeo..11..731R No abstract at ADS Title: Sydney Chapman, 1888-1970 Authors: Roberts, Walter Orr Bibcode: 1970Icar...13..354R Altcode: No abstract at ADS Title: After the Moon, the Earth! Authors: Roberts, Walter Orr Bibcode: 1970Sci...167...11R Altcode: No abstract at ADS Title: Book Reviews Authors: Goodman, J. W.; Roberts, W. O. Bibcode: 1967StAst..20...92G Altcode: Two items are reviewed: Intelligent Life in the Universe, by I. s. Shklovskii and Carl Sagan; and Neighbors of the Earth, edited and annotated by Thornton Page and Lou Williams Page. Title: Book Reviews Authors: Cruikshank, D. P.; Bartlett, J. C.; Gordon, R. W.; Roberts, W. O. Bibcode: 1967StAst..20...58C Altcode: The following are reviewed: Solar Radio Astronomy by Mikul R. Kundu; Names of the Plough by Antonio Paluzíe-Borrell; The Names of Orion and its Stars by Antonio Paluzíe-Borrel; The Names of the Minor Planets and their Meanings by Antonio Paluzíe-Borrel; Mariner IV to Mars, by Willy Ley; and The Moon, A Fundamental Survey, by Ralph B. Baldwin Title: Book Reviews Authors: Roberts, W. O.; Smith, J. R. Bibcode: 1967StAst..20...28R Altcode: Two items are reviewed: The American Ephemeris and Nautical Almanac For the Year 1967, issued by the Nautical Almanac Office, U. S. Naval Observatory; and 1967 Celestial Calendar and Handbook, authored and published by Chas. F. Johnson, Jr. Title: Book Reviews Authors: Roberts, W. O. Bibcode: 1966StAst..19..164R Altcode: 1966JALPO..19..164R The following were reviewed: Galaxies, Nuclei, and Quasars, by Fred Hoyle; Atlas Eclipicalis; Atlas Borealis; Atlas Australis; Photographic Star Atlas I/II; and Photographic Star Atlas III. Title: Book Reviews Authors: Hodgson, R. G.; Roberts, W. O.; Gordon, R. W. Bibcode: 1966StAst..19...86H Altcode: 1966JALPO..19...86H Three books are reviewed: Satellites of the Solar System, by Werner Sander; Kepler's Dream, by John Lear; and Lunar and Planetary Surface Conditions, by Nicholas Weil. Title: Atmospheric Sciences for the Space Age Authors: Roberts, Walter Orr Bibcode: 1966NASSP..82...40R Altcode: No abstract at ADS Title: Book Review Authors: Roberts, W. O. Bibcode: 1965StAst..19...25R Altcode: 1965JALPO..19...25R One book is reviewed: Wanderers in the Sky, edited with commentary by Thornton Page and Lou Williams Page. Title: Book Reviews Authors: Roberts, W. O. Bibcode: 1965StAst..18..199R Altcode: 1965JALPO..18..199R Two books were reviewed: Telescopes, edited by Gerard P. Kuiper and Barbara Middlehurst; The Dawn of Astronony, by J. Norman Lockyer. Title: The origin of M-region geomagnetic storms Authors: Billings, Donald E.; Roberts, Walter Orr Bibcode: 1964ApNr....9..147B Altcode: No abstract at ADS Title: Representation and representatives Authors: Waldmeier, M.; Ellison, M. A.; Roberts, W. O. Bibcode: 1962IAUTB..11...52W Altcode: No abstract at ADS Title: Corrigenda Authors: Roberts, W. O.; Zirin, H. Bibcode: 1961JGR....66..340R Altcode: No abstract at ADS Title: Recent Progress in Solar Physics Authors: Roberts, Walter Orr; Zirin, Harold Bibcode: 1960JGR....65.1645R Altcode: A number of significant recent advances in solar physics are reviewed. New kinds of observations made during the present sunspot cycle, which began in 1954, have emphasized still further the apparent complexity of solar phenomena and the need of nonequilibrium theoretical treatments. Among the new developments discussed are solar cosmic rays and high-energy particles, flares and prominences, coronal condensations, solar magnetic fields, and solar radio noise emission. Theoretical analyses of the conditions of the solar atmosphere as a hot plasma, and as a gaseous ensemble exhibiting gross departures from thermodynamic equilibrium, are discussed. New work on atomic collisional parameters is also reviewed. The article concludes with a synopsis of certain major unsolved problems of the solar atmosphere. Title: Further Evidence of a Solar Corpuscular Influence on Large-Scale Circulation at 300 Mb Authors: MacDonald, Norman J.; Roberts, Walter Orr Bibcode: 1960JGR....65..529M Altcode: Statistical evidence from three successive winter half-years strongly indicates that, when the earth is bombarded by unusually intense solar corpuscular emission, certain troughs in the 300-mb circulation are subsequently amplified. The troughs so affected enter or are formed in the Gulf of Alaska-Aleutian Islands area on the second, third, or fourth day after the start of the corpuscular increases. The trough amplifications maximize a variable number of days later, which may explain why the result was not apparent to earlier workers. The result has been found independently, at about the same level of significance, in the data each of the three winters treated separately. For the data of three half-years grouped together the probability of such a strong chance association is less than 10-6. Title: Evidence of a Solar Corpuscular Influence on Large-Scale Weather Phenomena. Authors: McDonald, N. J.; Roberts, W. O. Bibcode: 1960AJ.....65Q..54M Altcode: Statistical evidence from three successive winter half-years strongly indicates that when the earth is bombarded by unusually intense solar corpuscular emission, certain low-pressure troughs in the 300-mb circulation are subsequently amplified. The troughs so affected enter or are formed in the Gulf of Alaska-Aleutian Islands area on the second, third, or fourth days after the start of the corpuscular increases. The trough amplifications maximize a variable number of days later, and in different locations, which may explain why the result was not apparent to earlier workers. The same result has been found independently, at about the same level of significance, in each of the three winters treated separately. For the three halfyears grouped together the probability of so strong a chance association is less than 10-6. Title: Atmospheric Magnetic Filelds above Active Solar Region of April 13, 1950. Authors: Correll, Malcolm; Roberts, Walter Orr Bibcode: 1958ApJ...127..726C Altcode: We have analyzed a period of well-observed prominence activity over a clear-cut active at central meiidian passage (CMP) on April 13,1950, at N. 13 heliographic latitude. Good-quality Climax west-limb prominence films in Ha revealed that the region had an associated homogeneous field of motions that extended from the region to more than 7 X l0 km We found that the trajectories could be well described by assuming that they lay along the lines of force of a magnetic dipole buried 0 03 solar radii below the solar surface, with its axis tilted +50 from the plane of projection The projection of the axis was approximately radial There is evidence that a solar radio-noise storm at meter wave length was associated with the region and was emitted parallel to the dipole axis rather than in a radial direction from the active region There was also a geomagnetic disturbance so timed that it may well have resulted from solar corpuscles also emitted parallel to the dipole axis, at the same large angle from the solar radius. Title: Sun-Earth Relationships Authors: Roberts, Walter Orr Bibcode: 1958eas..conf....5R Altcode: No abstract at ADS Title: Department of Astro-Geophysics at the University of Colorado Authors: Roberts, Walter Orr Bibcode: 1957PASP...69..268R Altcode: No abstract at ADS Title: Optical evidences of radiational and corpuscular emission from active solar regions Authors: Roberts, W. O. Bibcode: 1957IAUS....4..336R Altcode: No abstract at ADS Title: Solar-Terrestrial Relationships: Weather and Communications Authors: Roberts, Walter Orr Bibcode: 1956SCoA....1...99R Altcode: No abstract at ADS Title: Some coronagraph spectra of chromosphere Authors: Roberts, Walter Orr Bibcode: 1956AJ.....61Q.189R Altcode: No abstract at ADS Title: Solar Corpuscles Responsible for Geomagnetic Disturbances Authors: Pecker, Jean-Claude; Roberts, Walter Orr Bibcode: 1955JGR....60...33P Altcode: A qualitative hypothesis is given that attributes recurrent "M-region" geomagnetic disturbances to the arrival at the earth of solar corpuscles that have been gathered into beams by the deflecting action of coronal-region fields, presumably magnetic, associated with centers of heightened solar activity. The hypothesis identifies the source of solar corpuscles that produces M-region magnetic disturbances with "quiet areas" of the solar surface. A related hypothesis associates non-recurrent magnetic storms, the greatest ones, with a different solar corpuscular source, found in the active region itself. Title: The Prominence of July 25, 1951. Authors: Rothschild, Kurt; Pecker, Jean-Claude; Roberts, Walter Orr Bibcode: 1955ApJ...121..224R Altcode: The motions of 49 knots in the large prominence of July 25, 1951, have been measured. For 17 of them, a definite variation of acceleration vectors has been found. The dynamics of the motion still remains obscure. It seems difficult to represent them by a coherent field of forces. Moreover, gravity seems to play no role in this prominence. Title: Coronal Line Intensities at the Khartoum Eclipse. Authors: Athay, R. G.; Roberts, W. O. Bibcode: 1955ApJ...121..231A Altcode: Coronal line and continuum intensities were measured at several position angles on the limb and as a function of height above the limb on the slitless spectrograms obtained at Khartoum by the High Altitude Observatory. The lines XX 5303, 6374, and 7892 and the continuum were measured at fifteen points around the limb. The relative line and continuum intensities around the limb showed large variations. In one active region where the emission in some lines was intense, the yellow coronal line X 5694 was observed. In this same region the lines X 6702 and X 7060 were intense enough to measure, and it was found that lines of high ionization potential were at maxima in intensities, whereas lines of low ionization potential were at minima. The yellow line was at maximum in this region, confirming that it is a high4oniza- tion-potentia] line. The correlation between line and continuum intensities was found to increase markedly as the ionization potential increased for the three lines studied. The correlation between line intensities was found to increase as the difference in ionization potential decreased. Intensities of X 5303, X 7892, and the continuum were measured as a function of height above the limb in four regions. Two of these regions were active centers, one of which showed the yellow line, and two were more nearly average regions. The change of X 7892 intensities with height in the latter two regions showed that the maximum intensity occurred below 10,000 km. Changes in the relative intensities of the two lines with height showed that in the yellow-line region the temperature decreased with height, but in the other regions the temperature increased with height. A comparison of the changes in line intensities to the changes in continuum intensities showed that the average temperature in the active regions was above the value at which the line X 5303 had a maximum intensity, but in the two more normal regions the temperature was between the limits where the lines X 5303 and X 7892 have maxima. The active regions were found to be regions of high density. Title: Identification of the Yellow Coronal Line. Authors: Pecker, Charlotte; Billings, Donald E.; Roberts, Walter Orr Bibcode: 1954ApJ...120..509P Altcode: Confirmation of Edinn's tentative identification of Ca xv as the atom responsible for the yellow coronal emission line X 5694 is given. From line-profile analysis, the atomic weight of the responsible atom is shown to be close to 40. The existence of an additional emission line at about X , demanded by theory and previously reported by Waldmeier, is verified. The ratio of the intensities X 5694/X 5446 is found to be in agreement with theoretical values for Ca xv emission. Title: Study of profiles of coronal emission lines. Authors: Billings, D. E.; Pecker, C.; Roberts, W. O. Bibcode: 1954AJ.....59..316B Altcode: Coronal lines occasionally show a marked broadening in those very active regions of the sun's atmosphere that are characterized by flares and yellow line emission.1 We have selected a number of spectrograms in which such broadening is apparent, and have subjected them to analysis, both by microphotometer and visually with a travelling microscope. Most of the work was on the red coronal line although in some cases the green and yellow line profiles were also analyzed. In one of the spectra, the distorted red line was clearly split into two parts separated by 3 A, indicating that one fragment of coronal material was moving away from the observer at approximately 150 km/sec. Such evidence of large-scale motion was very exceptional, however. Most of the broadened lines were surprisingly symmetrical. Half-widths, corrected for i nstru - mental profile on the assumption of Gaussian profiles, corresponded to temperatures ranging as high as sixteen million degrees, with the greater number studied corresponding to six or seven million degrees. Profiles of the red line in less disturbed regions consistently corresponded to a temperature about 2.3 X 106 degrees. The broadened profiles generally differed appreciably from Gaussian form in the direction of triangular profiles. We consider two interpretations for the line broadening, high temperatures and randomly distributed macroscopic velocities. According to the latter, and assuming a temperature of 2.3 X 106 degrees, we compute root mean square macroscopic velocities as high as 63 km/sec. The symmetry of the line profiles, however, suggests the high temperature hypothesis. One set of profiles of special interest is that of the yellow, red, and green coronal lines observed on February 2, 1950. When the abscissas of these profiles are corrected to the same wave length and atomic weight, using 40 for the atomic weight of the yellow-line emitting ion, the profiles coincide well within the limits of experimental error. This coincidence holds even though the shape of the profiles departs considerably from Gaussian. If, as Menzel has suggested to us, we interpret the shape of the profiles as a superposition of various temperatures along the line of sight, we need assume only that Edlen's original identification of the yell6w line as Ca xv is correct, and that the sources of coronal emission are distributed in the same proportion in the various temperature regions along the line of sight. If we adhere to the macroscopic velocity concept, we must postulate a very special distribution of velocities for the yellow-line emitting atoms, an improbable situation. We are confronted with the dilemma of the coexistence of atoms radiating Ha, and the coronal lines XX5303, 6374 and 5694 implying a wide range of ionization temperatures. A theoretical explanation of how this can occur has, however, been given by Goldberg and Meuzel.2 We find in active centers, moreover, a definite correlation between line broadening in Ha and in the red coronal line, suggesting independently the coexistence of these atomic species at comparable kinetic temperatures. This work was supported by the Office of Naval Research. I.Dolder, F. D., W. 0. Roberts, and D. E. Billings, Ap. J. 119, 120, 1954. 2.Centennial Symposia, pp. 279-297, Harv. Obs. Monogr. No. 7, 1948. High A ltitude Observatory, Boulder, Colo. Title: Solar corpuscles responsible for geomagnetic disturbances. Authors: Pecker, Jean-Claude; Roberts, Walter Orr Bibcode: 1954AJ.....59..330P Altcode: Some years ago C. W. Allen presented all extensive analysis of geomagnetic storms, and offered suggestions for their explanation in terms of streams of corpuscles originating in the sun.' We offer a qualitative hypothesis, that incorporates Allen's suggestions and identifies the solar source of corpuscular emission responsible both for recurrent and non-recurrent geomagnetic disturbances. We postulate two different types of solar sources of such particles as follows: (a) Small jets of corpuscles, distributed in a fine network all over the surface of the sun, and presumably associated with chromospheric spicules or photospheric granules. These jets, in the absence of deflecting solar magnetic fields, would send radial streams of corpuscles in all directions; the streams would be present at all times, regardless of the state of solar activity. In the presence of deflecting magnetic fields from active centers, and the general magnetic field of the sun, the corpuscles are deflected to form the streams responsible for the recurrent "M-region" geomagnetic disturbances. (b) Irregular streams of ions associated with active regions, and probably most intense at the time of solar flares. Not all active centers have such streams present at all times, and there is probably also a large dispersion of particle velocities and stream energies for this type of corpuscular stream. We present evidence from a study of geomagnetic disturbances in 1952-53 to support the hypothesis of the formation of recurrent magnetic storms by particle streams of the first type. In particular we find evidence that above certain active regions there is a "cone of avoidance" with low particle density. The center of the cone reaches earth three days later. We also show that there is some evidence that at the edges of the cone-of-avoidance the deficiency of corpuscles is compensated by regions with an excess particle density. The hypothesis is in accord with the explanation we gave earlier for the formation of the K component of the white light corona,' here associated with the solar-terrestrial corpuscular beams. The hypothesis suggests that daily coronagraphic observation of the white light corona may prove of great value for prediction of the times of occurrence of geomagnetic storms and associated phenomena. This work was supported by the Air Force Cambridge Research Center, Geophysical Research Directorate, Air Research and Development Command. 5.M. N. 104, 53, 5944. 2.Roberts, W. 0., R. Grenchik, and D. E. Billings, A. f. 58, 225, 5953. High Altitude Observatory, Boulder, Colo. Title: Active Region Prominences and the Yellow Coronal Line. Authors: Dolder, F. P.; Roberts, W. O.; Billings, D. E. Bibcode: 1954ApJ...120..112D Altcode: Regions of the sun characterized by emission of the rarely observed yellow coronal line X 5694 were found to be positively associated with the following characteristic behavior of prominences at the same location: (a) large numbers of associated surge-type prominences; (b) predominance of scattered knots; (c) formation of continuous streamers; (d) downward motion of knots and streamers toward an active center; and (e) sharp curvatures and focusing effects in trajectories. On the other hand, the principal observed characteristics of quiescent solar prominences were found to be negatively associated with the regions of yellow coronal-line emission. Title: The active region on the west solar limb during the eclipse of 25 February 1952. Authors: Athay, R. G.; Evans, J. W.; Roberts, W. O. Bibcode: 1954AJ.....59..182A Altcode: At the Khartoum eclipse there was an active region at io0S latitude on the west limb. This region was first observed as a small sunspot group and plage area near the east limb on 12 February. One flare was reported in this region on 13 February, one on i6 February, two on 24 February and two on 25 February."2 The west limb spectrograms of the chromospheric flash obtained by the High Altitude Observatory showed a small region of enhanced emission and immediately adjacent to it a small region of greatly reduced emission. Moon profile pictures taken at Khartoum showed that the observed effects could not be attributed to irregularities in the moon's profile. A few degrees away from these regions there was a bright prominence that appeared to be of a surge type. The region of reduced emission showed mainly in the chromospheric lines. There was also an apparent decrease in the coronal line intensities in the lowest levels of the corona, but there was no marked decrease in the continuum intensity. The decrease in the line intensities apparently resulted from either a cloud of absorbing matter or an actual decrease in chromospheric emission. The region of enhanced emission showed a maximum in the continuum and all chromospheric and coronal line intensities. The greatest increase in chromospheric lines was in He+, X4686. The yellow coronal line, X5694, showed in this region on our spectrograms. It did not show at any other positions, and to our knowledge has not been observed at previous eclipses. Lyot and Doilfus have also reported this coronal line and four new coronal lines from observations at Khartoum.3 All of these lines were found in this region of enhanced emission. The intensities of all of the chromospheric lines decreased much more slowly with height in this region than in an east limb region previously analyzed,4 which seemed to represent the undisturbed chromosphere. It was suggested that the region of enhanced emission was caused by a limb flare. A preliminary interpretation of the data from this region showed that both the electron density and kinetic temperature were greater than in the east limb region, and that the temperature increased less rapidly with height. A more detailed analysis of this region will be published elsewhere. This work was supported by the Office of Naval Research and carried out in cooperation with the Naval Research Laboratory. Title: Recent Studies of Chromospheric Spicules Authors: Rush, J. H.; Roberts, W. O. Bibcode: 1954AuJPh...7..230R Altcode: No abstract at ADS Title: Astronomy and Mathematics. (Book Reviews: Dialogue on the Great World Systems; Dialogue concerning the Two Chief World Systems--Ptolemaic & Copernican) Authors: Kuhn, Thomas S.; Nelson, E. C.; Kron, Gerald E.; Athay, R. Grant; Roberts, Walter Orr; Miller, Frederic H. Bibcode: 1954Sci...119..546K Altcode: 1954Sci...119..546G No abstract at ADS Title: Solar Flares and the Yellow Coronal Line. Authors: Dolder, Frederick P.; Roberts, Walter Orr; Billings, Donald E. Bibcode: 1954ApJ...119..120D Altcode: Emission of the unidentified yellow coronal line visible at Climax from 1946 through 1950 is shown to be highly correlated with flares at the sun's limb at the same position, indicating a close relationship between the two phenomena. The probability of a chance correlation as close as the observed is less than 2 X 10- . Title: The active region on the west solar limb during the eclipse of 1952 25 February Authors: Athay, R. G.; Evans, J. W.; Roberts, W. O. Bibcode: 1953Obs....73..244A Altcode: No abstract at ADS Title: Isophotal Photometry of a Solar Flare. Authors: Billings, Donald E.; Roberts, Walter Orr Bibcode: 1953ApJ...118..429B Altcode: The paper presents isophotal contour maps of the solar flare of April 12,1950, at various stages of development, and a plot of integrated intensity of the flare as a function of time. Our measurements indicate that at flare maximum the earth received a radiation of solar Ha energy/sec which exceeded "quiet' `-sun Ha radiation by nearly 2 X 1(V8 ergs/sec. The estimated total energy in Ha reaching the earth from the sun between the recognized start of the flare and its end exceeded that from the quiet sun for a corresponding time interval by approximately 9 X 1021 ergs. Title: Eruptive Prominence Associated with Limb Flare of may 8, 1951. Authors: Bartlett, Thomas J.; Witte, Bruno; Roberts, Walter Orr Bibcode: 1953ApJ...117..292B Altcode: A solar prominence of violently eruptive character accompanied the limb flare of May 8, 1951. Measures of several knots in the prominence show that forces large compared with solar gravitation were present, but no simple laws of motion emerge from the data. Title: Preliminary intensities of Balmer lines from the flash spectrum of the 1952 solar eclipse. Authors: Athay, R. G.; Billings, D. E.; Evans, J. W.; Roberts, W. O. Bibcode: 1953AJ.....58R..33A Altcode: Spectrographic observations of the flash spectrum at the February 25, 1952 solar eclipse at Khartoum, Sudan, were made by the High Altitude Observatory of Harvard University and University of Colorado. A primary purpose of the expedition was to obtain information about the hydrogen Balmer and Paschen series. This information, in turn, will be used to determine the electron temperature and electron density as a function of height in the chromosphere. The observations employed three slitless spectrographs covering the spectral range X88oo to X340o. *Of papers presented at the Eighty-eighth Meeting of the American Astronomical Society, Amherst, Mass., Dec. 28-31, 1952. We obtained 29 pairs of visible and 17 pairs of ultraviolet spectrograms from X6400 to X3400, which are of satisfactory quality. The 16 infrared spectrograms X88oo to X6100 are underexposed. Imaged on the film during each exposure were two simultaneous spectra, the pair having an intensity ratio approximately 30:1. Each exposure also contained a data panel. The data panel included clocks for determining the beginning and end of each exposure and a photographic step-wedge for checking the characteristic curve. Standard exposures from a tungsten ribbon-filament lamp taken on the same roll of film as the eclipse spectrograms, but separately processed, provide data for a first approximation to the characteristic curve at any desired wave length. Corrections carried out by comparing densities in the corresponding light and dark spectral images will then give us reliable characteristic curves. The distribution of densities in the coronal continuum gives further information for improving the accuracy of the characteristic curve. More direct determination of the characteristic curves is not possible because a part of the standardizing program failed at the time of the eclipse. Using the approximate characteristic curve obtained from the standard exposures, we made preliminary measures of the intensities of the Balmer lines near the series limit on 12 spectrograms at second contact. For this we worked from positive prints of the original spectra. The heights at which measurements were made extend from 700 km to 1930 km above the base of the chromosphere, with observations every 108 km. We found that the intensity of H31 is measurable to a height of 2150 km and the intensity of H23 is measurable to 2700 km. In some spectrograms a tentative identification shows H34, H35, and H36 to be resolved. We are now initiating a more complete and more accurate reduction of the data, working from the original films. The eclipse program of the High Altitude Observatory is supported by the Naval Research Laboratory, Office of Naval Research, and has been conducted in close collaboration with the Laboratory. Three of the four authors are connected with the High Altitude Observatory, J. W. Evans with the Upper Air Research Observatory. High A ititude Observatory, Boulder, Cob., and Upper Air Research Observatory, Sacramento Peak, Clouderoft, N. Mex. Title: Isophotal contour photometry of a solar flare. Authors: Billings, Donald E.; Roberts, Walter Orr Bibcode: 1953AJ.....58R..35B Altcode: The High Altitude Observatory recently constructed an electronic contour densitometer, following suggestions of Oliphant,1 and Babcock,2 which automatically plots isophotal contours from a photographic plate.3 Using the instrument we have plotted nine isophotal contour maps of a brilliant solar flare that began at 18:44 UT on 12 April 1950. By determining the brightness corresponding to the various contours of the maps, and measuring the areas within the contours, we have arrived at integrated intensities for the flare at nine stages in its development. By making certain assumptions concerning the average Ha line-width and the scattering in the 0.5 A birefringent filter that we used for photographing the flare, we have concluded that the total Ha energy per unit time in the solid angle subtended by the earth (i.e., the power that reached the earth from the flare) reached at maximum nearly 5 >C 1015 ergs!sec or approximately 2 per cent of that radiated to earth from the full solar disk in a I A band of the solar continuum adjacent to Ha. The estimated total energy in Ha reaching the earth from the flare between its recognized start at 18:44 UT and its end at 23:00 UT was approximately 2 X 1022 ergs. I.The Observatory 69, 228 (1949). 2.Pub. A. S. P. 62, i8 (1950). 3.F. E. Fowler, D. S. Johnson and D. E. Billings, J. Opt. Soc. Amer. (in press). High A ltitude Observatory, Boulder, Colo. A LIST OF 16 Ha EMISSION REGIONS BET~ Object b 3008 +i?~ Small faint nt NGC6193 304.5 -2.6 Over2~diam IC 4628 312.6 +0.4 Involved witi nehulosity. NGC 6281 315.5 +o.8 McD 70. Exc: NGC6302 316.3 -1.0 Appears like NGC6334 318.8 -o.8 5small,very NGC 6357 320.9 +0.3 Contains Wol NGC6383 323.3 -1.3 Large faint 323.4 -0.5 Small faint 334 -3 Large field of NGC 6559. IC 1284 339.3 -3.3 Includes NG( complex 341 -3 Small Sagitta 342.5 +1.9 Small, faint r M17 342.8 -2.2 Very intense Mi6 344.7 -o.6 Very strong ii NGC6Oo4 346.1 -0.2 Large,faintn the Boyden Station of Harvard Observatory. The principal instrument used in the southern survey is a camera with a ~-inch Zeiss Sonnar lens (f/I.5), on loan from Mr. Richard S. Perkin, fitted with a Corning 2403 red filter and a Baird Ha interference filter. In the present paper we report on the distribution of Ha emission regions between galactic longitudes 2650 and 3550 Dr. Dorrit Hoffleit is reporting elsewhere on the remarkable concentration of Ha emission regions between galactic longitudes 2500 and 2650. The photography for the section between 1800 and 2500 is still in progress. We list in the accompanying table, the 16 regions of Ha emission that seem to be well established. We are still checking on an additional group of ten uncertain regions and some further doubtful patches. A list of associated 0 and B stars has been prepared and these are now on the Boyden Station spectral and photo-electric programs for further study to determine their distances. The most noteworthy result of our study is probably the absence of any but the very weakest Ha emission between galactic longitudes 2650 and 3000. There is obviously a gap or break in Title: Evolution of coronal regions. Authors: Billings, D. E.; Liebenberg, D. H.; Roberts, W. O. Bibcode: 1953AJ.....58S.211B Altcode: The authors have examined the behavior of regions in the solar corona near sunspot groups, which show intense coronal line emission. The results led them to formulate the following working hypothesis of the origin of the emission line corona. I. Yellow, red and green line emission at XX 5694, 6374 and 5303 in a coronal region becomes pronounced with infusion into the corona of gas of density considerably higher than that of the corona prior to the infusion. 2. The infusion takes place most strongly from active sunspot centers during their periods of flare activity. 3. The gas spreads out through the corona along magnetic lines of force at about I km/sec, at a sufficient rate to replace the entire emission corona in the order of a few weeks. 4. As the gas spreads out, its temperature rises slowly. 5. Resulting temperature and density conditions are such that yellow line emission persists for several hours, red line emission for a few days, green line emission for about a week or two. 6. The coronal region drops below a recognizable level of brightness as the gas expands to a low density, but before the return to normal in its temperature. This concept, arrived at from a study of coronagraphic data, agrees with that suggested by Piddington and Davies from solar radio noise observations.1 The principal observational data which led to the concept are: A. The close association of coronal emission and flare activity. B. The spreading out of isophotal contours of coronal emission at a rate of about 2' km/ sec during the growth of the coronal region and sometimes after the sunspot and flare activity at the center has subsided. This slow spread is perhaps related to the behavior of the "disparitions brusques" reported by Bruzek following solar flares.2 C. Many cases of a unidirectional change of the ratio of red line to green line emission, usually downward, during a rise and fall of brightness of coronal regions. We see no way to explain this last observation by the hypothesis that coronal regions differ from the remainder of the corona only in that they are of higher temperature. We can, however, explain it by the spreading gas hypothesis. This work was carried out with the support of the Office of Naval Research. I.Nature 171, 692, 1953. 2.Zs. Astroph. 31, 99, 1952. High Altitude Observatory, Boulder, Cob., and University of Wisconsin, * Madison, Wis. Title: Origin of white-light coronal streamers. Authors: Roberts, W. O.; Grenchik, R.; Billings, D. E. Bibcode: 1953AJ.....58S.225R Altcode: Two hypotheses were adyanced for the explanation of the shape of individual rays or streamers of the electron corona seen in white light during eclipse, and sometimes found extending to distances of several solar diameters. In the first, the shape was ~onsidered to be simply the shape of the net magnetic field resulting from the combination high in the corona of the individual magnetic fields above two active solar regions separated by angles of the order of 600 or more of the solar surface. In this hypothesis, the fields were taken as being similar to isolated magnetic poles, with the field smoothly dropping off with increasing distances from the region, and recognizable to distances of the order of 200,000 km. The fields responsible for a ray or streamer must, on this hypothesis, be of same sign. The ray then results from illumination of electrons constrained by the field to move parallel to it. The electrons, in this picture, are swept up from chromospheric jets or spicules over the entire quiet surface between the focussing field centers. The hypothesis, though it gave suitable streamer shapes, ran into serious troubles in explaining other aspects of the electron corona. However, a new hypothesis, closely related to the first, seems to explain the principal observed features of the electron corona in qualitative fashion, at least. In this, the isolated poles responsible for the focussing are of opposite polarity, and the steady-state streamer shape results from the distorting effect of the particle energies which, in this view, carry the magnetic field lines far out into the solar atmosphere. The hypothesis explains general coronal shape variations, with sunspot activity, the quiet sun coronal form, and the relationship of coronal rays to M-region magnetic storms described by Allen in 1944.1 Some support for the concept is provided by solar radio noise observations by Payne- Scott and Little.2 The qualitative success of the hypothesis suggests the importance of a concerted theoretical attack on the problem. I.AL N. 104, 13, 1944. `2. AI~st. J. Sci. Res. ~A, 32, 1952. High Altitude Observatory, Boulder, Colo., and University of Indiana,* Bloomington, Ind. Title: Solar limb flares and the yellow coronal line. Authors: Dolder, Frederick P.; Roberts, Walter Orr Bibcode: 1953AJ.....58R..37D Altcode: A list of all solar flares published in the I. A. U. Quarterly Bulletin of Solar A clivity for 1946 through 1950, when treated by simple statistical procedures, reveals an unmistakable degree of association between flares that occurred within ~O of the solar limb and the 43 instances of occurrence in this period of the yellow coronal line observed at Climax and Sacramento Peak. The probability for a number of chance coincidences equal to or greater than the observed number is less than 2 X I0-~. Additional evidences of association between the yellow coronal line and solar prominences exist. Prominences associated with this line showed, for example, decidedly more marked tendencies towards downward motion and towards apparent inflow of material from "space" than did prominences in general. The yellow line prominences showed more tendency towards breaking up into scattered knots, and less tendency towards formation of large stable masses than did prominences chosen at random. The results combine to suggest that there is a strong relationship between solar prominences of the character associated with the yellow coronal line and areas of the sun exhibiting intense coronal line emission in X5303 and X6374 of Fexiv and Fex. The work reported here was supported by the Office of Naval Research. High Altitude Observatory, Boulder, Colo. Title: Continuous Solar Survey, Cinematography, and Electronic Sun-Follower Authors: Roberts, Walter Orr Bibcode: 1953sun..book..653R Altcode: No abstract at ADS Title: Recent studies of chromospheric spicules. Authors: Rush, J. H.; Roberts, W. O. Bibcode: 1953AJ.....58R.226R Altcode: Two film sequences of spicules at the south polar zone of the sun, taken in 1949 with the Climax coronagraph in Ha, were analyzed. These films were run at 6 frames/min. for a combined duration of 92 min. Both films agreed on an upper limit of 22,000 spicules having lifetimes of 0.3 min. or greater on the entire sun at a given time, assuming uniform distribution. The lifetimes of 400 spicules were determined, but could not be corrected for the effects of spatial distribution in the line of sight. The number of spicules having a given lifetime was inversely proportional to the lifetime. The mean lifetime was about 4 min., confirming an earlier result.1 Nearly all spicules were radial to the sun. Upward speeds of 64 spicules ranged widely about a mean of 32 km/sec. Apparent downward displacements were observed in many cases, at speeds loosely correlated with upward speeds. Whether apparent descent represented return of material or progressive fading of intensity is not known. The coefficient of correlation between maximum heights and upward speeds was 0.7. Neither heights nor upward speeds were significantly correlated with lifetimes. The spicules occurred randomly in time. The data suggested correlation of some characteristics with latitude; but any such relations were so intermingled with observational and other selection factors that they could not be verified. The film reductions for this study were carried out by a group under the direction of Dr. Z. Kopal at the Massachusetts Institute of Technology. The research was supported in part by the Office of Naval Research;the National Bureau of Standards, Research Corporation, and the Radio Corporation of America. I.W. 0. Roberts, Ap. J. 101, 136, 1945. High Altitttde Observatory, Boulder, Colo. Title: Sunspot Prominences and the Yellow Coronal Line. Authors: Roberts, Walter Orr Bibcode: 1952ApJ...115..488R Altcode: A study of twenty-five cases of bright emission of the yellow coronal line X 5694, from 1946 through 1951 revealed close association between this emission and fast-moving prominences of the "sunspot" type. It also showed that unusually sharp discontinuities and intensifications of the red coronal line X 6374 occurred at the regions where the yellow coronal line was seen. In a few cases small Doppler effects in X 6374 also appeared at the solar-limb position of the X 5694 emission. The observations lead to the preliminary speculation that the source of the emission corona lies in a few, relatively small, active regions scattered over the solar disk. Title: Sunspot prominences and the yellow coronal line. Authors: Roberts, Walter Orr Bibcode: 1951AJ.....56Q.138R Altcode: The results are given for part of a research program now in progress. Twenty-five cases of the occurrence of bright emission of the yellow coronal line 5694 A have been studied thus far. Of these, a preponderance shows the coronal line to be closely associated with sunspot prominences exhibiting unusually high activity and large velocities. Some speculations are given regarding the possible relationship of the yellow coronal line emission to the outbreak of solar flares. High Altitude Observatory, Harvard University, and University of Colorado, Climax, Colo, Title: Solar activity at the time of the eclipse of September 12, 1950. Authors: Roberts, Walter Orr; Trotter, Dorothy; Witte, Bruno Bibcode: 1951AJ.....56R..47R Altcode: Solar coronal observations were carried out at the Climax and Sacramento Peak coronagraph stations on the days preceding and following the total solar eclipse visible at Attu Island, Alaska, on September 12, 1950. We combined these observations to get isophotal contour maps of the sun's green line coronal emission for September I 1, 1950, treating the data from each station independently. We also obtained detailed prominence observations from both stations at times as close to the eclipse date as possible. The coronal contour maps show that there were intense green-line coronal emission zones near the east limb in both hemispheres, and near the central meridian in the northern hemisphere. The coronal intensities near the west limb were relatively low. On the other hand, the total area of all limb prominences of the west limb greatly exceeded the total area of all east-limb prominences. Except for one region of the maps, the two stations gave results that were reasonably concordant. In one area, about three days west of the central meridian and about 250 north, there were substantial disagreements of an unexplained origin. Some evidence exists that this region was also one of unusually changeable coronal emlssion. Solar flare observations could not be made at Boulder on September II or 12 because of cloudy weather. However, September was a month of generally lower solar activity than prevailed during the earlier portions of the year. This Research was supported in part by the Central Radio Propagation Laboratory of the National Bureau of Standards and the Air Force Cambridge Research Laboratory. High A ltitude Observatory, Boulder, Coto. Title: New observations of solar spicules. Authors: Roberts, Walter Orr; Brenton, Virginia K.; Shapley, Martha B.; Kopal, Zdenek Bibcode: 1950AJ.....55R..80R Altcode: We have analyzed three coronagraph films taken to show the small hydrogen prominences we have called spicules. The films were made with a 4 A pass birefringent filter at Climax, Colorado. Two were taken in December 1943; one in February 1946. The frequency distribution of lifetimes shows that the spicules have very short mean lifetimes of the order of two minutes for all the films. Mean ascent velocities for the spicules on the 1946 film substantially exceed those for the two 1943 films which have mean velocities which are close together. Strong observational selection, however, affects all measures of velocity. Moreover, we cannot be sure that the velocities typical of the larger spicules represent the velocities of the far more frequent smaller spicules which it is difficult to measure. However, the results suggest a time-variation of the mean ascent velocity; this variation may be in phase with general solar activity variations. High Altitude Observatory, Boulder, Colo. andDepartment of Electrical Engineer~ng, Massachusetts Institute of Technology, Cambridge, Mass. Title: Observation of Chromospheric Opacity Authors: Roberts, Walter Orr Bibcode: 1950PASP...62..219R Altcode: 1950HarRe.341....1R No abstract at ADS Title: Further Measures of Chromospheric Spicules Authors: Roberts, Walter Orr; Brenton, Virginia K.; Shapley, Martha B.; Kopal, Zdenek Bibcode: 1949PASP...61..160R Altcode: No abstract at ADS Title: Association of Corona with Prominence. Authors: Roberts, Walter Orr Bibcode: 1948ApJ...108..523R Altcode: 1948HarRe.317....1R A coronal spectrogram, taken on June 14, 1947, shows a striking association between X 6374 of the corona and X 6563 of an active prominence; at the same position the rarely observed unidentified coronal line X 5694 shows clearly. The positions of sharp maxima of the prominence spectrum and of the coronal spectrum coincide precisely for the two brightest parts of the prominence. Some likelihood appears to exist that the occurrence of A 5694 is generally associated with the occurrence at the same place on the sun of rapidly moving prominences of the "sun-spot" type Title: Association of solar corona and prominence. Authors: Roberts, Walter Orr Bibcode: 1948AJ.....54...48R Altcode: A coronal spectrogram taken 011 14 J une 1947 showed a striking association between ~6374 of the corona and X6563 of an active prominence. At the same position, the rarely-observed unidentified coronal line ~5694 showed clearly. The positions of sharp maxima of the prominence spectrum and of the coronal spectrum coincided precisely for the two brightest parts of the prominence. There is some likelihood that the occurrence of X5694 is generally associated with the occurrence at the same place on the sun of rapidly moving prominences of the "sun-spot" type. On at least one occasion, significant line-ofsight velocities have been observed in the coronal line ~6374, associated with such "sun-spot type" prom in ences. High A ltitude Observatory of Harvard University and University of Colorado, Climax, Colorado Title: Solar Activity Authors: Roberts, Walter Orr Bibcode: 1948HarMo...7..299R Altcode: 1948cent.symp..299R No abstract at ADS Title: The Correlation of Magnetic Disturbances with Intense Emission Regions of the Solar Corona. Authors: Shapley, A. H.; Roberts, W. O. Bibcode: 1946ApJ...103..257S Altcode: Correlation analyses of coronal and magnetic data, during the period August, 1942-July, 1944, show that, on the average, magnetic disturbance occun~ed when intense emission regions of the solar corona were situated in the eastern hemisphere of the visible solar disk. Some specific comparisons are cited with regard to the correspondence of coronal-emission regions and M-regions. Although there are some valid criticisms of the methods of correlation used thus far, the results demonstrate that a correla- tion does exist and that more refined and complete analysis is indicated to realize fully the value of coronal observations as applied to short-term forecasts of disturbance. The observing procedure used at, the Coronagraph Station of the Harvard College Observatory at Climax, Colorado, and the uncertainties of observation are detailed in the appendix Title: A Preliminary Report on Chromospheric Spicules of Extremely Short Lifetime. Authors: Roberts, Walter Orr Bibcode: 1945ApJ...101..136R Altcode: 1945HarRe.271....1R Small spikes of chromospheric material, observed in Ha with the coronagraph and quartz-polaroid monochromator, are described. These spicules, seen in polar regions of the sun, have very brief lifetimes, amounting on the average to 4 or 5 minutes. The typical spicule is low in brightness and has a height at maximum of less than 15 seconds of arc. At least in polar regions, they appear to be present in greater or smaller numbers at all times. The spicules are apparently distributed at random in the polar regions stud- ied. The behavior of the spikes, while well typed, exhibits considerable variation. Possible association with polar coronal "plumes" and with "rice grains" of the disk is discussed Title: Preliminary Studies of the Solar Corona and Prominences with the Harvard Coronagraph. Authors: Roberts, Walter Orr Bibcode: 1943PhDT.........1R Altcode: No abstract at ADS Title: On Possible Changes in the Solar ``Constant'' Authors: Sterne, Theodore Eugene; Guthe, Karl Frederick; Roberts, Walter Orr Bibcode: 1940PNAS...26..399S Altcode: 1940HarRe.203....1S No abstract at ADS