bluuebunny/crossref_metadata_2025 huggingface dataset:
The Eclipsing Binary WX Eridani
Authors: Sarma M.B.K. , Abhankar K.D.
Published: July 2016

The Algol-type eclipsing binary WX Eridani was observed on 21 nights on the 48-inch telescope of the Japal-Rangapur Observatory during 1973-75 in B and V colours. An improved period of P = 0.82327038 days was obtained from the analysis of the times of five primary minima. An absorption feature between phase angles 50-80, 100-130, 230-260 and 280-310 was present in the light curves. The analysis of the light curves indicated the eclipses to be grazing with primary to be transit and secondary, an occultation. Elements derived from the solution of the light curve using Russel-Merrill method are given. From comparison of the fractional radii with Roche lobes, it is concluded that none of the components have filled their respective lobes but the primary star seems to be evolving. The spectral type of the primary component was estimated to be F3 and is found to be pulsating with two periods equal to one-fifth and one-sixth of the orbital period.
The Period / Luminosity / Colour Relation for the β CMa Stars
Authors: Shobbrook R. R.
Published: July 2016

Recently published new β indices for most of the β CMa stars (Shobbrook, 1978a, b, Papers I and II), plus Crawford’s (1978) β/Mvcalibration can be used to define a new period/ luminosity/ colour (P/L/C) relation for these variables. It has been pointed out by the author in the above mentioned papers that the intrinsic width of the instability strip is about 0.2 mag. in Mv; a three parameter solution including also the period promises to be even better defined.
Statistics and parallaxes
Authors: Lutz T. E.
Published: July 2016

This review paper deals with the use of statistical methods to evaluate systematic and random errors associated with trigonometric parallaxes. First, systematic errors which arise when using trigonometric parallaxes to calibrate luminosity systems are discussed. Next, determination of the external errors of parallax measurement are reviewed. Observatory corrections are discussed. Schilt’s point, that as the causes of these systematic differences between observatories are not known the computed corrections can not be applied appropriately, is emphasized. However, modern parallax work is sufficiently accurate that it is necessary to determine observatory corrections if full use is to be made of the potential precision of the data. To this end, it is suggested that a prior experimental design is required. Past experience has shown that accidental overlap of observing programs will not suffice to determine observatory corrections which are meaningful.
Contributions of various instrumental parameters and defects to parallax determinations
Authors: Ianna P. A.
Published: July 2016

The difference in parallaxes of the same star measured at different observatories has been a source of concern and discussion for many years. The purpose of these remarks is to emphasize the point that systematic errors in parallaxes must be region specific, that is, they can be expected to be different for each and every star. It seems to me unlikely that a generally applicable constant can be found that would bring one observatory’s parallaxes inline witn anothers. Tnis must especially be the case for older parallaxes obtained with refracting telescopes. Essentially this same point was raised by Schilt many years ago (1). There is some evidence suggesting this to be the case.
Review of radio astrometry I. Radio measurements
Authors: Elsmore B.
Published: July 2016

At the astrometry symposium held at Perth in 1973, the radio astronomers devoted much of their allocated time towards explaining the techniques used in radio astrometry. As further details are available in, for example, the review by Counselman, it now seems appropriate to consider the achievements that have been made since the last symposium.
Experimental determinations of the right ascensions of Mercury using the radio-telescope RATAN-600
Authors: Afanasyeva P. M. , Fomin V. A.
Published: July 2016

Regular and accurate determinations of angular coordinates of the planets are necessary to solve many important problems of fundamental astrometry and celestial mechanics. Mercury is the most difficult planet for accurate optical observations. Due to close position to the Sun its positional observations are made only with meridian instruments and only in broad day light. Having the accuracy of the order of 1” these observations are very scarce and made only near the moments of elongation of the planet.
Photoelectric astrometry: a comparison of methods for precise image location
Authors: Lindegren L.
Published: July 2016

Several techniques for obtaining the precise location of a noisy image (of a star, spectral line, solar limb, etc.) are described by means of characteristic “weighting functions”. The imprecision of an image location estimate can be expressed in terms of the weighting function and the image shape and noise covariance. It is limited by the intrinsic imprecision of the image, which is attained with an optimum weighting function, computable from the image characteristics. The hypothetical optimum method is compared with some commonly used location methods, such as computing the median or centre of gravity, least-squares fitting and cross correlating, and hardware techniques including the quadrant detector and rotating knife-edge. One- and two-dimensional Gaussian images are considered as well as diffraction and seeing images. The general results apply also to photographic astrometry, measurement of radial velocities, timing of pulses, etc.
Applications of automated inventory techniques to astrometry
Authors: Benedict G. F. , Shelus P. J.
Published: July 2016

Devices now exist which allow for the automatic inventorying of photographic plates. Applications of these techinques to three astrometric problems are described, as are resulting accuracies. General remarks on the inventory techniques and program design are presented. A potential application to Space Telescope is outlined.
Accuracy of binary star speckle interferometry
Authors: McAlister H. A.
Published: July 2016

Nearly 400 speckle interferometric observations of binary stars with separations between 0033 to 325 obtained with the 4 meter Mayall telescope at Kitt Peak have been analyzed for accidental and systematic errors in order to determine the reliability of the error estimates assigned to single measurements and to develop schemes for correcting for possible systematic effects. The calibration technique currently in use limits the accuracy to ±0.6% of the angular separation and to ±02 in position angle. Comparison of 101 observations to published orbits of high quality gives mean residuals and r.m.s. errors of <Δθ> = -00005±00072 and <Δρ> = 00051±0158. Small systematic errors can be introduced into separation measurements unless the spatial frequency power spectrum for a single, unresolved star is subtracted from the two dimensional power spectra for binary stars. Residuals to published orbits have been compared to magnitude differences and angular separations in order to search for systematic dependences on these parameters. It is generally concluded that the published error estimates for the author’s speckle observations are realistic estimates of their accuracies.
The proper motions of the AGK 3 R and SRS Stars
Authors: Corbin T. E.
Published: July 2016

The AGK3R and SRS are lists of reference stars containing, respectively, 21,499 stars in the Northern Hemisphere and about 20,500 stars in the Southern Hemisphere. Eleven transit circles contributed to the observations of the AGK3R. The program was a differential one based on theFK4, and the average mean epoch of observation is 1959.0. The compilation of the SRS is still in progress at the U.S. Naval Observatory. As Dr. Hughes has just explained, the SRS positions also will be referred to the system of the FK4, and the mean epochs of observation will be in the latter part of the 1960’s. My task has been to compute the proper motions for these two groups of stars that will permit the use of the observed positions away from the epochs of observation. Since the proper motions of the AGK3R stars have been completed, I will report on that work first.
Present status of Lohrmann Program
Authors: Böhme D. , Sandig H. U.
Published: July 2016

On the IAU Symposium No. 61 in Perth there was delivered a paper “by Deutsch and Klemola (1974) with some information into a program to be started at Dresden (in cooperation with the Zentralinstitut für Astrophysik at Potsdam), which was called Lohrmann Program by the authors mentioned. In a similar way as the extensive programs already in realization in Lick and Pulkovo the Lohrmann Program has on the one hand the aim to determine absolute proper motions by connection of weak stars with suitable extragalctic objects. On the other hand shall be examined systematic errors for the AGK3. First of all we examined (1971 to 1976) carefully the Schmidt version of the Tautenburg 2m reflector belonging to the Zentralinstitut für Astrophysik of the Academy of Sciences. Besides we did set up a program of fields to be taken by the Schmidt, first of all a pilot program.
The Use of Bayesian Statistics in Image Estimation from Interferometer Data
Authors: Cornwell T. J.
Published: July 2016

The problem of estimating radio sky brightness distributions from incomplete, and noisy, visibility measurements, such as those collected by a long baseline interferometer, has recently been attacked using nonlinear data-adaptive techniques such as the Maximum Entropy method (Abies (1974), Wernecke (1976), Wernecke and D’Addario (1977), Gull and Daniell (1978)) and the Maximum Likelihood method (Papadopoulos (1975)).
Analysis of High Resolution Stellar Line Profiles
Authors: Gray David F.
Published: July 2016

High resolution implies that we obtain some information on spectral line shapes. In late-type stars, we need to measure velocities of a few km/sec to accomplish this. Increasing the spectral resolution and the signal to noise ratio allows us to progress step by step toward deeper physical understanding. The steps we take often lead to good debate and “stimulate” our lives. I am sometimes amused at the urgency we feel to press on to the next step. We rarely seem to pause and enjoy the completion of previous steps. Perhaps this is because we always see shortcomings in completed work. Quite typically one will “discover” the importance of some physical phenomenon (It makes little difference how many others already know about it.), and in his eyes everything done previously becomes wrong because this phenomenon was not included. We used to hear how Milne-Eddington or Schuster-Schwarzschild model atmospheres were inadequate -we had to use instead properly computed depth dependence. We used to hear how LTE models were no good - we had to use more detailed physics. Now we talk about line analyses being inadequate because it has not included velocity fields. The curious thing is that we believe that including our pet phenomenon gives the correct models. We ignore all those other phenomena as yet unseen! (Is this a mechanism for maintaining sanity?) I think it really amounts to a statement of what we are able to measure, compute, or understand.
High Luminosity F-K Stars Motions and Hα Emissions
Authors: Smolinski J. , Climenhaga J.L. , Harris B.L.
Published: July 2016

Changes and differences in radial velocities between neutral and ionized metals have been found for three F5-type supergiants: HD 231195, HD 10494, and HD 17971. Fifteen high dispersion coudé spectrograms (6 Å/mm) were used and 33 to 165 lines were measured on each. Semi-regular time variations up to about 8 km s-1 in radial velocity have been found. In addition, Hα line profiles for 8 high luminosity F-K stars have been analyzed. All of the stars show Ha emissions, variable in time, which is probably a common phenomenon in very luminous stars. Metallic emission lines with low excitation potentials, in particular the Ca I 6572.8 and the Fe I 6574.2 lines, are present in 5 of these stars.
Small-Scale Versus Large Scale Motions in the Solar Atmosphere Derived from A Non-Lte Calculation of Multiplet 38 of Ti I
Authors: Cayrel R. , Dumont S. , Martin P.
Published: July 2016

A non-LTE computation of multiplet 38 of Ti I (11 lines) has been undertaken in order to determine small and large scale unresolved motions contributing to the Doppler broadening of solar lines at the centre of the disk (vertical motions) and at the edge of the disk (horizontal motions).

The abundance of Titanium and the total Doppler velocity (all scales) are determined by fitting observed and computed profiles of weak unsaturated lines (W < 12 mÅ) of the multiplet. Then saturated lines having the same lower level as the weak lines are computed for a variety of partitions of the total kinetic energy between the small scale and the large scale modes going from 0% small scale to 100% small scale. Oscillator strengths with internal accuracies of about 2% from Wahling (1977) have been used. The location of the observed profile (taken from Delbouille et al. for the centre of the disk and from Brault and Testerman, KPNO for μ 0.2) among the computed profiles yields the partition of the energy between the two modes.

The computations done so far with 4 levels and continuum give less than 20% of the energy in the small scale mode. Further computations with more levels are needed to establish this ratio with better accuracy. The total energy for vertical motions has a root square velocity of about 1.4 km/sec whereas the same quantity is 2.2 km/sec for horizontal motions.
Summary
Authors: Böhm-Vitense Erika
Published: July 2016

Let me start by saying that we have heard some excellent review papers and I doubt very much that I can contribute much of importance in addition to what we have heard already.

1 also wish to apologize to all those who have made important contributions during this meeting and who will not be mentioned in this 30-minute summary. If I wanted to mention everybody I would just have enough time to read the program.
Collapse of Accreting White Dwarf to Form a Neutron Star
Authors: Nomoto Ken’ichi , Miyaji Shigeki , Sugimoto Daiichiro , Yokoi Koichi
Published: July 2016

In a close binary system with a primary star in the mass range 8-12 M⊙, the primary star leaves a white dwarf composed of 16O, 20Ne, and 24Mg as a result of mass exchange. When the companion star, fills its Roche lobe, overflowing matter accretes onto the white dwarf. We have computed the evolution of such an accreting O-Ne-Mg white dwarf and found that electron captures on 24Mg and 20Ne trigger the collapse when the mass reaches 1.38 M⊙. As a result of the collapse, oxygen begins to deflagrate but the effects of electron captures dominate over the oxygen deflagration. The white dwarf collapses to form a neutron star.
IUE Observations of White Dwarfs and Hot Subdwarfs
Authors: Oke J. B.
Published: July 2016

The International Ultraviolet Explorer (IUE) has been used by Greenstein and Oke to obtain low resolution spectra from 1150 to 3200 Å of a selection of white dwarfs and hot subdwarfs.

The observations can be converted to absolute fluxes so that, by including energy distributions measured with the multichannel spectrometer on the Hale telescope, fluxes can be derived between 1150 and 11000 Å. The IUE absolute fluxes show erratic level shifts of up to 20 percent and probably also smaller changes in the slope. These shifts are probably associated with the level of the radiation induced background coupled with uncertainties in the calibration of the non-linear detectors. In many cases, these anomalies in the fluxes are obvious, but they do decrease the accuracy with which temperatures and gravities can be determined.
Effects of Nuclear Burning on X-Ray and UV Emission from Accreting Nonmagnetic Degenerate Dwarfs
Authors: Weast G. J. , Durisen R. H. , Imamura J. N , Kylafis N. D. , Lamb D. Q.
Published: July 2016

The energy liberated by nuclear burning of matter accreting onto degenerate dwarfs can be more than an order of magnitude greater than that available from the release of gravitational potential energy. Nuclear burning therefore significantly alters the characteristics of X radiation from such stars. Here we report the results of calculations in which steady burning occurs at the accretion rate, and compare them with our calculations (Kylafis and Lamb 1979, hereafter KL) which assumed no burning. These two studies illustrate the maximum and minimum effects of nuclear burning. Results for intermediate burning rates can be found by scaling from them.
The Magnetic Fields of Single White Dwarfs
Authors: Landstreet J.D.
Published: July 2016

The first magnetic field in a white dwarf was discovered nine years ago (Kemp et al. 1970). Since that time magnetic fields have been detected in a total of 12 single white dwarfs and four white dwarfs in close binary systems. These magnetic fields have been found both through the Zeeman splitting and shifting of spectral lines and through the continuum circular (and sometimes linear) polarisation which a field may produce in the optical flux of a star in which it occurs. The fields so far detected appear to range between 3 MG and more than 100 MG. For stars with fields less than about 40 MG, both the observed Zeeman shifts of spectral lines and the observed circular polarisation appear to be reasonably well understood. For stars with fields above this level, attempts so far to identify absorption features in the spectra and to account for the continuum polarisation have not been very successful; indeed, there is considerable dispute about the fundamental mechanism producing the continuum polarisation, especially the linear component.
Magnetic White Dwarfs with Strong Fields and the Origin of Magnetism in White Dwarfs and Neutron Stars
Authors: Angel J. R. P.
Published: July 2016

Work in progress at Steward Observatory covering three aspects of magnetism in degenerate dwarfs is reviewed. First, the identification of the Minkowski bands in Grw + 70° 8247 with Zeeman transitions in hydrogen. Second, a determination of field strengths in the more strongly magnetic white dwarfs. Third, some observations and speculations concerning the origin of white dwarf and neutron star magnetic fields.
Radial Pulsation Analyses of DA Dwarfs
Authors: Starrfield S. , Cox A. N. , Hodson S. W.
Published: July 2016

There are now twelve ZZ Ceti stars known and their properties are summarized by Nather (1978) and McGraw (1977, 1979). They have normal DA spectra and their colors range from a B-V of 0.18 mag to 0.22 mag. This places them on the HR diagram in a region which is an extension to the white dwarfs of the Cepheid instability strip. This would suggest that the cause of their pulsation could be analogous to the κ and γ mechanisms of the Cepheids except for the fact that the periods of the ZZ Ceti stars range from 200 to 1200 seconds, three orders of magnitude larger than the radial pulsation periods for white dwarfs.
AAVSO’s Astronomical Data Bank
Authors: Mattei Janet Akyüz
Published: July 2016

The AAVSO founded in 1911 is the largest organization of variable star observers in the world, with 1100 members in 49 states and 38 countries. AAVSO Headquarters, in Cambridge, MA, receives about 150,000 observations a year from about 400 active observers. Since 1911, over 4 million observations have been compiled. The limiting visual magnitude of observations is about AAVSO’s observing program contains about 2000 variable stars of the following types: Mira (825); semiregular (350); cataclysmic-U Gem, Z Cam, nova, recurrent nova, novalike, symbiotic (200); cepheid (120); R Coronae Borealis (20); RV Tauri (30); nebular (100); flare (15); irregular (140); suspected variables (200). AAVSO has finder charts for most of the stars.
Is the Outburst of U Scorpii an Accretion Event?
Authors: Webbink R.F.
Published: July 2016

A summary of the peculiarities of the spectral evolution of the recurrent nova T Cr B are given, and interpreted in terms of an episodic accretion model. On the basis of the marked similarity of U Sco with this nova, it is suggested that the observed maximum will be followed by a secondary maximum, reaching V = 14-15. Such a secondary maximum should be very different for an accretion event (showing a strong continuum) and a thermonuclear outburst (showing a nebular spectrum). If observations of a star at 14th magnitude at the position of U Sco in February 1969 were indeed of a secondary maximum of this nova, the principal maximum probably precedes the secondary by less than 65 days.
Sodart Telescope on Spectrum-Röntgen-Gamma and its Instrumentation
Authors: Schnopper Herbert W.
Published: July 2016

SPECTRUM-RÖNTGEN-GAMMA (SRG) is one of a new series of large astronomical missions being planned by the Soviet Union and is scheduled for launch in mid-1993. The Space Research Institute (IKI) of the Academy of Sciences of the USSR and the Babakin Center (BC) are responsible for the scientific supervision and spacecraft construction, respectively. Mission objectives include broad and narrow band imaging spectroscopy over a wide range of energies from EUV through gamma rays with particular emphasis on extragalactic objects. The design of the Soviet Danish Röntgen Telescope (SODART) consists of two thin foil, conical shell approximations to Wolter 1 geometry. The reflectors are rolled aluminum foils which have been dipped in acrylic lacquer and coated with gold resulting in a super smooth surface. Each telescope has an aperture of 60 cm, a focal length of 8 m, a field of view of 1 deg and is designed to have a halfpower width of ≤2 arcmin. The conical geometry contributes 15 arcsec and manufacturing tolerances in the support structure and the quality of the figure of the foil the rest. The contribution from X-ray scattering is insignificant. Focal plane slides can position one of four instruments at the focus of each telescope. Images and spectra will be recorded with position sensitive proportional counters with spectral resolution as good as 13% at 6 keV. Spectral resolution of 2.5% at 6 keV is provided by an array of 19 cooled silicon detectors. A broad band polarimeter will be sensitive to residual polarization as low as 1%. An objective Bragg crystal panel, placed in front of one of the telescopes, will be capable of high resolution spectroscopic studies ((E/ΔE)) ~1000) of point- and extended sources.
An Overview of the Orbiting Solar Laboratory
Authors: Spicer D.S.
Published: July 2016

The Orbiting Solar Laboratory (OSL), which is a joint NASA/BMFT/ASI/ AFGL program, will be a free flying, polar orbiting complement of five scientific instruments operating as a facility and designed to observe the surface and upper atmosphere of the sun with high spatial and temporal resolution over a spectral range from the soft X-ray to the near Infrared. OSL’s primary scientific objectives are to study the coupling of velocity, magnetic, and radiation fields in the photosphere and chromosphere and to causally relate this coupling to activity in the overlying regions.

To study the photosphere and chromosphere with a spatial resolution approaching 75 km OSL will utilize a 1 meter telescope, optimized for 2000–11,000 Å, to feed a narrow band tunable filter, a set of fixed broad-band filters, and a spectrograph. These three instruments share a common structure, share a unified science data and control system, and use a single-image stabilization system for their common fields of view to form a Coordinated Instrument Package (CIP). To study the transition zone a stigmatic High Resolution Telescope Spectrograph (HRTS) optimized for 1175–1700 Å, will be used capable of providing both images and spectroscopic information. A X-Ray Extreme Ultraviolet Imager and Spectroheliograph (XUVI) optimized for the 40–400 Å regime, will allow study of the corona and of multimillion degree solar transient events such as flares. Both the HRTS and the XUVI instruments will possess image stabilization systems and have a resolving power of 350 km. All OSL instruments will operate overlapping fields of view and be co-aligned. To achieve its goals the OSL will provide a total data stream of 20 M bits/s, nominally 4 M bits/s per instrument and has a planned operational lifetime of three years.
The Astrometric Imaging Telescope: Near-Term Discovery and Study of Other Planetary Systems
Authors: Levy Eugene H. , Gatewood George D. , Terrile Richard J.
Published: July 2016

The Astrometric Imaging Telescope (AIT) is a space-based 1.5 to 2 meter diameter telescope designed to discover and study planetary systems around other stars. The measurement objectives and instrument design aim at a definitive search for other planetary systems. The science program includes two planetary-system investigations, and the telescope carries two separate instruments: an astrometric instrument to measure the reflex motions of stars caused by the motions of unseen planets and an imaging coronagraph to directly image planets and other circumstellar matter.
Use of Libration-Point Orbits for Space Observatories
Authors: Farquhar Robert W. , Dunham David W.
Published: July 2016

The Sun-Earth libration points, L1 and L2, are located 1.5 million kilometers from the Earth towards and away from the Sun. Halo orbits about these points have significant advantages for space observatories in terms of viewing geometry, thermal and radiation environment, and delta-V expediture.
An X-Ray All Sky Monitor for a Japanese Experimental Module on the Space Station
Authors: Matsuoka M. , Kawai N. , Imai T. , Yamauchi M. , Yoshida A. , Kohno T. , Yoneda A. , Tsunemi H.
Published: July 2016

We propose an X-ray all sky monitor for Japanese Experimental Module (JEM) on the space station. Considering practical circumstances, we show as a case study that the all sky monitor with slit hole cameras is most promising for monitoring the short-term and long-term X-ray transients. We call this all sky monitor as MAXI (Monitor of All-sky X-ray Image). Position determination of gamma-ray bursts could be achieved with accuracy less than one degree observing the X-ray component of the burst. Weak X-ray sources such as active galactic nuclei could be also monitored with time resolution less than one day. The X-ray all sky monitor will work to discover X-ray novae and transient phenomena and give us the alarm for further detailed observations. The obtained data will be also used for archival study.
Transport of Solar Energetic Particles
Authors: Dröge Wolfgang
Published: July 2016

New developments in the understanding of the interplanetary transport of solar cosmic rays are reviewed. Based on carefully analyzed solar particle events observed on the Helios and ISEE 3 spacecraft, the relation of transport parameters to the structure of the interplanetary magnetic field is discussed. Special emphasis is given to a comparison of particle mean free paths determined from fits to intensity and anisotropy profiles with theoretical predictions derived from magnetic field spectra measured at the time of the solar particle event. Different aspects of the turbulence and wave models for the magnetic fluctuations are considered, including the effects resulting from the finite temperature of the plasma and of resonance broadening. It is found that a modified quasi-linear theory of particle scattering taking into account the effects of plasma waves propagating with respect to the average solar wind flow and the proper treatment of the dispersion relation at high wavenumber gives results which are in several cases in good agreement with particle observations in the interplanetary medium between 0.3 and 1 AU, indicating that quasi-linear theory is probably a good approximation to a full theory of solar particle transport. This has important implications for other astrophysical problems where quasi-linear theory is often used, such as the propagation and acceleration of Galactic cosmic rays and particle acceleration at shock waves.

Subject headings: acceleration of particles — cosmic rays — interplanetary medium — MHD — solar wind — Sun: particle emission
Solar Hard X-Ray and Gamma-Ray Observations from GRANAT
Authors: Vilmer N.
Published: July 2016

Hard X-rays and gamma-rays are the most direct signature of the energetic electrons and ions which are accelerated during solar flares. Since the beginning of 1990 the PHEBUS instrument and the SIGMA anticoincidence shield aboard GRANAT have provided hard X-ray and gamma-ray observations of solar bursts in the energy range 0.075-124 and 0.200-15 MeV, respectively. After a brief description of the experiments, we present some results obtained on solar bursts recorded in 1990 and 1991 June. Special emphasis is given to the results related with particle acceleration during solar flares.

The first part of the review is devoted to the constraints obtained on the electron acceleration timescale through the analysis of the temporal characteristics of the bursts. Combined studies of hard X-ray and gamma-ray emissions from PHEBUS and radio emissions from the Nançay Multifrequency Radioheliograph are used to infer constraints on the coronal magnetic topology involved in flares. The characteristics (location, spectrum) of the radio-emitting sources are found to vary within a flare from one hard X-ray peak to the other. Hard X-ray and gamma-ray burst onsets and rapid increases of the > 10 MeV emission are coincident with changes in the associated radio emission pattern. These results will be discussed in the context of the flare energy release.

The second part of the paper concerns the heliocentric angle distribution of > 10 MeV events and presents more detailed observations of some of the largest flares in the gamma-ray line and the high-energy domains produced by ultrarelativistic electrons and > 100 MeV nucleon−1 ions. The PHEBUS observations of the gamma-ray line flare of 11 June 1991 have been used to deduce the hardness of the accelerated ion spectrum. The link between the main part of the flare and the late long-lasting >50 MeV emission detected by EGRET/COMPTON is discussed. Finally some observations of the large 1990 May 24 flare which produced a large neutron event at ground level are presented.

Subject headings: acceleration of particles — Sun: flares — Sun: radio radiation — Sun: X-rays, gamma rays
Energetic-Particle Abundances in Impulsive Solar Flare Events
Authors: Reames D. V. , Meyer J. P. , von Rosenvinge T. T.
Published: July 2016

We report on the abundances of energetic particles from impulsive solar flares, including those from a survey of 2283He-rich events, with3He/4He > 0.1, observed by theISEE 3spacecraft from 1978 August through 1991 April. The rate of occurrence of these events corresponds to ~1000 events yr−1on the solar disk at solar maximum. Thus the resonant plasma processes that enhance3He and heavy elements are a common occurrence in impulsive solar flares. To supply the observed fluence of3He in large events, the acceleration must be highly efficient and the source region must be relatively deep in the atmosphere at a density of more than 1010atoms cm−3.3He/4He may decrease in very large impulsive events because of depletion of3He in the source region.

The event-to-event variations in3He/4He, H/4He,e/p, and Fe/C are uncorrelated in our event sample. Abundances of the elements show a pattern in which, relative to coronal composition,4He, C, N, and O have normal abundance ratios, while Ne, Mg, and Si are enhanced by a factor ~2.5 and Fe by a factor ~7. This pattern suggests that elements are accelerated from a region of the corona with an electron temperature of ~3-5 MK, where elements in the first group are fully ionized (Q/A =0.5), those in the second group have two orbital electrons (Q/A~ 0.43), and Fe hasQ/A~ 0.28. Ions with the same gyrofrequency absorb waves of that frequency and are similarly accelerated and enhanced. Further stripping may occur after acceleration as the ions begin to interact with the streaming electrons that generated the plasma waves.

Subject headings: Sun: abundances — Sun: flares — Sun: particle emission
Solar Simple Bursts Observed with High Spectral Resolution in the 18-23 GHz Range
Authors: Sawant H. S. , Rosa R. R. , Cecatto J. R. , Gopalswamy N.
Published: July 2016

For the first time, solar bursts in the frequency range of (18-23) GHz have been observed with high-time (0.6-1.2 s) and high-frequency resolution (1 GHz), by using the Itapetinga 13.7m diameter antenna. Here, we investigate the microwave type “simple low level (< 10 SFU) bursts” associated with the impulsive phase of solar flares. Observed properties of these simple bursts are: rise time tr ~3 s, decay time td ~ 5 s and spectral index ranging between −1 and −4. These bursts were found to be associated with SF or SN flares as seen in Hα. The above properties suggest that they are likely to be a microwave counterpart of elementary flare bursts. In the majority of the cases the spectral evolution is soft-hard-soft. This suggests a nonthermal gyrosynchrotron mechanism for generating these elementary flare bursts. Estimated parameters of these simple burst sources are height (h ~ 2400 km), electron density (Nє < 8.8 × 109 cm−3 ), and magnetic field (B ~ 300 G).

Subject headings: radiation mechanisms: nonthermal — Sun: radio radiation
Efficiency for Electron Acceleration in Solar Energy Release Region as Estimated in the Context of Plasma Mechanism of Radio Emission
Authors: Levin B. N. , Fridman V. M. , Sheiner O. A.
Published: July 2016

The paper is devoted to the interpretation of spectrographic data within the frequency range 8-12 GHz. Some spectral characteristics of weak solar steplike radio bursts are reported. To explain some parameters of the emission the ability to keep superthermal electrons in a magnetic trap with dense inhomogeneous plasma is theoretically studied. On the basis of this model we estimate the energy and number of accelerated electrons, and the flux density of precipitating electrons which are the source of enhanced plasma radiation. For the obtained efficiency of electron acceleration the calculated intensity of gyrosynchrotron emission proves to be less than the observed one.

Subject headings: acceleration of particles — radiation mechanisms: nonthermal — Sun: flares — Sun: radio radiation
Radiation-Driven Acceleration in Photospheres of Nonaccreting Magnetic White Dwarfs
Authors: Zheleznyakov Vladimir V. , Serber A. V.
Published: July 2016

Radiation transfer in a pure hydrogen, fully ionized, isothermal photosphere of an isolated white dwarf with dipole magnetic field is considered, and the radiation pressure force, both in the continuum and in the cyclotron line, is determined with the line saturation effect taken into account. It is shown that the magnetic field can reduce the critical luminosity for white dwarfs. This leads to the possibility of photospheric plasma ejection driven by the radiation in the cyclotron line and the formation of radiation-driven winds from sufficiently hot isolated magnetic white dwarfs.

It is shown that cyclotron radiation pressure plays a significant role in the force balance of the photospheres of the magnetic white dwarfs GD 229, GrW +70° 8247, and PG 1031+234. The strong unidentified depression in the UV spectrum of GD 229 is attributed to cyclotron scattering by the radiation-driven plasma envelope with density N ≳ 108 cm−3 .

Subject headings: radiative transfer — stars: atmospheres — stars: magnetic fields — white dwarfs
Hubble Space Telescope Observations of Synchrotron Jets
Authors: Sparks W. B. , Biretta J. A. , Macchetto F.
Published: July 2016

The Hubble Space Telescope for the first time enables optical and UV images of jets to be obtained with spatial resolution comparable to radio interferometric techniques. Because synchrotron emission at these wavelengths is a diagnostic of particles several orders of magnitude higher in energy and correspondingly shorter in lifetime than those probed by radio, the sites of particle acceleration may be more readily identified in the optical and UV. Short-lifetime optical synchrotron emission in the SE inner radio lobe of M87 argues strongly for the presence of an invisible counterjet. A detailed comparison of HST and VLA images of the M87 jet shows there are very strong similarities in overall morphology, but that there are also significant differences. The optical and UV radiation is more localized within the knots than the radio emission and appears more confined toward the jet center. These differences may arise from localized shocks, sited at the optical knots with diffusion of relativistic particles away from those knots, or else they may be due to nonuniform magnetic fields and distributed acceleration processes. The UV fluxes of the knots are consistent with a single power law from optical to X-ray. Optical jets in other radio galaxies show diverse properties—the jet of PKS 0521–36 is smoothly resolved by HST while that of 3C 66B shows previously unsuspected filmentary structure. Likewise, the jet of 3C 273 shows newly observed optical filaments and an intensity distribution quite unlike that of the radio emission. Like M87, the optical jet of 3C 273 is narrower than the radio jet. The serendipitous discovery of a new optical synchrotron jet in 3C 264 suggests that optical jets may be relatively common.

Subject heading: galaxies: jets
MONET: a MOnitoring NEtwork of Telescopes
Authors: Hessman Frederic V.
Published: July 2016

In an age of 8m-class telescopes, we should rethink the way we use small telescopes. While 2-4m telescopes are still needed and will continue to be operated largely in the traditional fashion, new 1m-class telescopes operated robotically in global networks will enable a wide range of new and exciting scientific and educational projects, both by themselves and in conjunction with much larger telescopes. I describe our plans for such a global network of two 1m-class robotic telescopes.
The STARBASE Network of Telescopes and the Detection of Extrasolar Planets
Authors: McGruder Charles H. , Everett Mark E. , Howell Steve B.
Published: July 2016

A network of longitudinally spaced imaging telescopes is described. Due to the limitations of the radial velocity method extrasolar planets have only been found around bright stars (less than 10 mag). Employment of the network and the photometric method to detect extrasolar planets will lead to the discovery of extrasolar planets at much fainter magnitudes (less than 19 mag).
YSTAR: Yonsei Survey Telescopes for Astronomical Research
Authors: Byun Yong-Ik , Han Won-Yong , Kang Yong-Woo , Chun Moo-Young , Yu Sung-Yeol , Park Sun-Youp , Kim Sang-Chul , Moon Hong-Kyu , Shin Jong-Seop , Lee Kyu-Baek
Published: July 2016

The YSTAR program is a general sky survey looking for variability. The main equipments are three 0.5-m telescopes. These telescopes have fast F/2 optics covering nearly 3.5 square degree field onto a 2K CCD. They also have very fast slew capability, which exceeds 10 degrees per second. These two factors make them most suitable for rapid target acquisition and wide-field surveys of various kinds. Our primary objective is to identify and monitor variable stars down to 18th R-magnitude, and our observing mode allows the same data set to be also useful in identifying asteroids. Our first telescope has just begun regular automated operation, and the second telescope will be installed in South Africa within this year to provide coverage of the southern sky.
Progress Report for the KAO 1.0 meter Robotic Telescope
Authors: Mack Peter , Han Wonyong , Bradstreet Matthew , Borstad Anthony , Park Jang-Hyun , Jin Ho , Lee Woo-Baik , Lee Chung-Uk
Published: July 2016

Korea Astronomy Observatory (KAO) is working to rebuild a 1.0-m robotic telescope in collaboration with a company (Astronomical Consultants & Equipment, Inc. or ACE). The telescope is being totally refurbished to make a fully automatic telescope which can operate in both interactive an fully autonomous robotic modes. This paper describes the design concepts and the work completed. The telescope is an f/7.5 Ritchey-Chretien system mounted on an equatorial fork with friction drives capable of high slewing (5°/s2) and high resolution tracking. The control software manages the entire telescope, instruments and observatory. In interactive local and remote modes the observer can manually enter coordinates or retrieve them from a database. In robotic mode the telescope controller downloads requests from users and creates a schedule. The telescope will be equipped with a CCD camera and will be available over the internet.
The Multiple Telescope Telescope, an Inexpensive Fiber Fed Spectroscopic Facility
Authors: Riddle Reed L. , Bagnuolo William G.
Published: July 2016

A unique telescope dedicated to spectroscopy is discussed. This instrument, the Multiple Telescope Telescope, uses many novel approaches to achieve high quality, medium to high resolution spectroscopy at low cost.
The Beijing Astronomical Observatory Supernova Survey
Authors: Qiu Yulei , Hu Jingyao , Li Weidong
Published: July 2016

We present here the Beijing Astronomical Observatory Supernova Survey (BAOSS). The motivation and the strategy of the survey are briefly discussed, and the hardware and the software of the system are described. BAOSS started in 1996 and has discovered 40 supernovae (SNe) in four years, thus playing an important role in the search for nearby supernovae. The results of several well-observed SNe discovered by BAOSS, SNe 1996W, 1996cb, 1997br, and 1998S, are reported.
High Speed CCD Photometry of Flare Stars
Authors: Park Sun-Youp , Byun Yong-Ik
Published: July 2016

Previously, flare stars have been observed by fast two channel photoelectric photometry. We have started an observing program to monitor flare stars using a normal CCD camera via a method called “trailed mode photometry”. For this program, we developed a fully automated trail photometry software.
Blazhko Cycles of ω Centauri RRab Stars
Authors: Jurcsik Johanna
Published: July 2016

The present observational strategy of globular cluster variables does not favour long observational runs, which are needed to study the modulation properties of Blazhko type RR Lyrae stars. The only globular cluster for which we have enough data (both photographic and CCD) to determine modulation cycles of RRab stars is ω Centauri. Any connection between the modulation periods and other stellar or cluster parameters may serve as a new clue to the explanation of the Blazhko phenomenon.
The Taiwan-America Occultation Survey for Kuiper Belt Objects
Authors: King Sun-Kun
Published: July 2016

The purpose of the TAOS project is to directly measure the number of Kuiper Belt Objects (KBOs) down to the typical size of cometary nuclei (a few km). In contrast to the direct detection of reflected light from a KBO by a large telescope where its brightness falls off roughly as the fourth power of its distance to the sun, an occultation survey relies on the light from the background stars thus is much less sensitive to that distance. The probability of such occultation events is so low that we will need to conduct 100 billion measurements per year in order to detect the ten to four thousand occultation events expected. Three small (20 inch), fast (f/1.9), wide-field (3 square degrees) robotic telescopes, equipped with a 2,048 × 2,048 CCD camera, are being deployed in central Taiwan. They will automatically monitor 3,000 stars every clear night for several years and operate in a coincidence mode so that the sequence and timing of a possible occultation event can be distinguished from false alarms. More telescopes on a north-south baseline so as to measure the size of an occultating KBO may be later added into the telescope array. We also anticipate a lot of byproducts on stellar astronomy based on the large amount (10,000 giga-bytes/year) of photometry data to be generated by TAOS.
The True Colors of KBOs
Authors: Hsu Hui-Chun , Ip Wing-Huen
Published: July 2016

The existence of a population of large planetoids outside the orbit of Neptune predicted by GP Kuiper, KE Edgeworth and JA Fernandez has been confirmed by ground-based observations.The physical properties of these Kuiper Belt Objects (KBOs) remain elusive. Photometric measurements have indicated that they have diverse color variations. A theoretical model is formulated to simulate the evolution of the surface materials of the KBOs under the influence of cosmic ray irradiation and meteoroid impacts. The long-term goal is to couple this theoretical model to observations and laboratory experiments such as LARA (Laboratory Astrochemistry and Astrophysics).
High Spatial Resolution Observations of the 1998 and 1999 Leonid Meteors
Authors: Jiang X.J. , Hu J.Y.
Published: July 2016

We observed the Leonid meteor storm in 1998 and 1999. The light curves extracted from the 2-dimensional images of the bright Leonid meteors clearly show the sub-structures, which are consistent with the generally accepted dustball meteor model (Hawkes & Jones, 1975).
Systematic Spectroscopic Observations on Small Telescopes: Past and Future Research of Stellar Kinematics
Authors: Sachkov M.E. , Glushkova E.V. , Rastorguev A.S.
Published: July 2016

We have used a CORAVEL-type spectrometer on small telescopes (70-cm, Moscow observatory, Russia; 60- and 100-cm, Simeiz observatory, Crimea, Ukraine and some others) for systematic observations of northern sky stars, since 1987 (Rastorguev & Glushkova, 1997; Gorynya et al., 1998). The typical accuracy of a single measurement is about 0.5 km/s. The limiting magnitude is 14 in V-band. The young Galaxy disk population, metal-poor stars and Kaptein selected areas are the important parts of our program. In this paper we present new results on galactic kinematics and our future program.
Deprojection of Planetary Nebulae
Authors: Zhang Z.W. , Ip W.H.
Published: July 2016

Useful information can be obtained by deprojection of the two-dimensional images of extended objects such as planetary nebulae or supernova remnants. Three-dimensional distributions (assumed to be axially symmetric) of emissivity, electron number density and temperature might be derived from the deprojected structures. As a test, we follow the iterative algorithm of Leahy & Volk (1994) to project the images of several PNe taken at different wavelengths. This method can also be applied to the images of supernova remnants and galaxy clusters.
Vector Potential Magnetic Null Points
Authors: Galsgaard Klaus , Nordlund Åke
Published: July 2016

Recent observations (Tarbell et al., 1990; see also Ruzmaikin et al. these Proceedings) show that the surface distribution of magnetic fields on the solar surface is selfsimilar, with an approximately constant fractal dimension over a large range of horizontal scales. Also, recent ideas about flare energy release assumes a “fibrous” corona, with the energy release consisting of many small scale events (Vlahoz, 1989) Prompted partly by these observations, we investigate the properties of self-similar three-dimensional magnetic fields.
The Solar Internal Rotation and its Implications
Authors: Paternò Lucio
Published: July 2016

The present internal rotation of the Sun as deduced from helioseismological data has many implications which concern the location of the solar cycle dynamo mechanism, core magnetism and history of the angular momentum. These aspects and their mutual connections are briefly discussed.
The Main Component Analysis of the Longitudinal Distribution of Solar Activity
Authors: Hejna Ladislav , Wöhl Hubertus
Published: July 2016

In this contribution, preliminary results of the main component analysis of Bartels diagram of time series of daily values of sunspot group numbers for solar cycles 18, 19 and 20 are presented. The results obtained suggest that the most significant feature in the longitudinal distribution of sunspot activity is the existence of preferred solar hemispheres alternating with a mean period of 2.5 Bartels rotations.
Rotation of Large Scale Patterns on the Solar Surface as Determined from Filament and Millimeter Data
Authors: Pohjolainen S. , Vršnak B. , Teräsranta H. , Urpo S. , Brajša R. , Ruždjak V. , Jurač S. , Schroll A.
Published: July 2016

The rotation of large scale solar magnetic field patterns was studied using quiescent filaments and low temperature regions observed at 37 GHz as tracers.