Lunar Occultation Observations Research Articles

La correspondance astronomique entre Joseph-Nicolas Delisle et Tobias Mayer.

SUMMARY. — The texts of the ten letters which passed between the astronomer- cartographers Joseph- Nicolas Delisle (1688-1768) and Tobias Mayer (1723-1762) published here for the first time, cover the period 21 August 1748 - 27 January 1751, while Mayer was employed by the Homann cartographic bureau in Nuremberg on an extensive series of astronomical observations of lunar occultations and parallax, and measurements of the angular diameters of the sun and moon. These were destined to form the basis of a method for the determination of longitude at sea. At this time, however, both correspondents were interested in using such data as a means of improving the accuracy of terrestrial longitudes for their maps ; the longitude difference between Paris and Nuremberg, the latitude of Nuremberg, and the spheroidicity of the Earth's shape were therefore the principal matters of mutual concern.

Corrections to fundamental constants from photoelectric observations of lunar occultations

Observations of photoelectric timings of occultations of stars by the Moon in the period 1955 to 1978 are analysed in order to determine corrections to the FK4 stellar reference frame and the constants of the lunar theory.

Photoelectric observations of lunar occultations. XIII

view Abstract Citations (16) References (9) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Photoelectric observations of lunar occultations. XIII. Blow, G. L. ; Chen, P. C. ; Edwards, D. A. ; Evans, D. S. ; Frueh, M. Abstract Occultation observations made with the 0.76 m reflector at McDonald Observatory are presented, for 319 events occurring between Jan. 15, 1981 and Feb. 7, 1982. One table reports timings, and a second records observations of 16 double stars, in particular, Nu Gem observations reveal that the two close components are similar in color. This allows an estimation of individual visible magnitudes (near 4.60 and 5.32) suggesting that the secondary is a late B-type main-sequence star. SAO 158929 observations reveal systematic differences in angular diameter values. Of the 16 observed double stars, 9 appear to be new discoveries, including SAO 93067, SAO 94595, and SAO 98770. A third table gives fully darkened angular diameters for the stars SAO 158929, SAO 77516 Y Tau, and SAO 119035 Nu Vir. Publication: The Astronomical Journal Pub Date: November 1982 DOI: 10.1086/113247 Bibcode: 1982AJ.....87.1571B Keywords: Astronomical Catalogs; Electrophotometry; Lunar Occultation; Stellar Spectrophotometry; Astrometry; Diameters; Astronomy full text sources ADS | data products SIMBAD (308) Related Materials (15) Part 1: 1970AJ.....75..575N Part 2: 1970AJ.....75..583N Part 3: 1970AJ.....75..589E Part 4: 1970AJ.....75..963N Part 5: 1971AJ.....76.1107E Part 6: 1973AJ.....78..482D Part 7: 1975AJ.....80..689A Part 8: 1976AJ.....81..650A Part 9: 1977AJ.....82..631A Part 10: 1978AJ.....83.1100A Part 11: 1980AJ.....85..478E Part 12: 1981AJ.....86.1277E Part 14: 1983AJ.....88.1845E Part 15: 1985AJ.....90.2360E Part 16: 1986AJ.....92.1210E

Lunar occultation stellar angular diameter measurements. III

view Abstract Citations (18) References (35) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Lunar occultation stellar angular diameter measurements. III. Beavers, W. I. ; Cadmus, R. R. ; Eitter, J. J. Abstract Additional stellar angular diameter measurements obtained by two-color photoelectric lunar occultation observations are reported. Within this set of 21 candidate events, nine yield measurable angular diameters, five are interpreted to be of unresolved stars, and seven proved to be too noisy for reliable analysis. Publication: The Astronomical Journal Pub Date: May 1982 DOI: 10.1086/113161 Bibcode: 1982AJ.....87..818B Keywords: Astrometry; Diameters; Lunar Occultation; Stellar Spectrophotometry; Stellar Structure; Electrophotometers; Point Sources; MOON; OCCULTATIONS; DIAMETERS; PHOTOELECTRIC OBSERVATIONS; ANALYSIS; DATA; PROCEDURE; COMPARISONS; Astronomy; Moon full text sources ADS | data products SIMBAD (17) Related Materials (2) Part 1: 1980AJ.....85.1505B Part 2: 1981AJ.....86.1404B

Lunar occultation observations of 15 Abell clusters at 327 MHz

The results of high-resolution, metre-wavelength observations, together with optical identification data, are presented for 17 discrete sources that dominate the radio emission from the direction of 15 Abell clusters. With only two exceptions, all the sources have been resolved. The sample contains two head-tail sources, including that in the X-ray emitting cluster Abell 401. The spectral indices of both the head and tail components of this source are found to be ≈ 0.8 and the size of its tail exhibits no strong dependence on the observing frequency.

Photoelectric observations of lunar occultations. XI

view Abstract Citations (18) References (8) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Photoelectric observations of lunar occultations. XI. Edwards, D. A. ; Evans, D. S. ; Fekel, F. C. ; Smith, B. W. Abstract Occultation observations of 466 events are presented. These include diameter measures of Aldebaran under very bad conditions and a good diameter measure of 82 Vir. The list includes 91 reappearances and observations of 34 double or multiple stars, both new and previously known. The inconsistencies of the observations of Kui 88 are discussed. Further observations are most desirable. Publication: The Astronomical Journal Pub Date: April 1980 DOI: 10.1086/112700 Bibcode: 1980AJ.....85..478E Keywords: Astrometry; Astronomical Catalogs; Lunar Occultation; Tables (Data); Binary Stars; Diameters; Astronomy full text sources ADS | data products SIMBAD (427) Related Materials (15) Part 1: 1970AJ.....75..575N Part 2: 1970AJ.....75..583N Part 3: 1970AJ.....75..589E Part 4: 1970AJ.....75..963N Part 5: 1971AJ.....76.1107E Part 6: 1973AJ.....78..482D Part 7: 1975AJ.....80..689A Part 8: 1976AJ.....81..650A Part 9: 1977AJ.....82..631A Part 10: 1978AJ.....83.1100A Part 12: 1981AJ.....86.1277E Part 13: 1982AJ.....87.1571B Part 14: 1983AJ.....88.1845E Part 15: 1985AJ.....90.2360E Part 16: 1986AJ.....92.1210E

Small-scale structure of the CO emission in S255 from lunar occultation observations

Two lunar occultations of the S255 H II region/molecular cloud complex were observed in the 2.6 mm CO line during 1978 and 1979. The resolution obtained (between 4 arcsec and 7 arcsec) enables us to resolve bright sources that are much smaller than the 44 arcsec telescope beam. In addition to the large-scale structure (approximately 10 arcmin in size) seen in previous CO maps, the observations reveal two high-temperature emission regions in the cloud core associated with two compact infrared sources about 20 arcsec apart. The first CO hot spot is larger in size with a Gaussian width of 41 arcsec + or - 7 arcsec and a peak temperature of 65 K. Its center falls between the two small infrared sources S255 IRS1 and IRS2. The linear size and peak temperature of this source are remarkably similar to those in the Orion Kleinmann-Low nebula. The second source is revealed from a discontinuous change in the CO line flux as the lunar limb crossed S255 IRS1. The size of this component is less than 7 arcsec; its temperature must exceed 200 K. No evidence is found for exceptionally high temperatures at the boundary of the two H II regions crossed during the occultations.

Lunar occultation observations of the Crab Nebula

view Abstract Citations (11) References (14) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Lunar occultation observations of the Crab Nebula. Maloney, F. P. ; Gottesman, S. T. Abstract Three lunar occultations of the Crab Nebula were observed; two at 114 MHz and one at 26.3 MHz, during the 1974 series of events. At the higher frequency, four strip-integrated brightness profiles were Fourier inverted to synthesize a two-dimensional map of the Nebula to an effective resolution of 30 arc sec. At 114 MHz, the Nebula is composed of a broad envelope of emission which contains several smaller sources. The presence of this small-scale structure is probably due to the ionized elements in the filaments. The 26.3 MHz observations indicate the presence of a bright, localized source containing greater than 80% of the flux of the Nebula. The position of this source is confined by the data to a narrow strip centered at the pulsar NP 0532. Publication: The Astrophysical Journal Pub Date: December 1979 DOI: 10.1086/157519 Bibcode: 1979ApJ...234..485M Keywords: Crab Nebula; Lunar Occultation; Pulsars; Radio Sources (Astronomy); Brightness; Radio Telescopes; Spectral Resolution; Astrophysics; Crab Nebula:Lunar Occultations; Crab Nebula:Radio Maps; Crab Nebula:Structure full text sources ADS |

The diameter of Aldebaran and Hyades occultations

view Abstract Citations (25) References (11) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The diameter of Aldebaran and Hyades occultations. Beavers, W. I. ; Eitter, J. Abstract The angular diameter of Aldebaran (Alpha Tauri, K5 III) has been measured by using photoelectric lunar-occultation observations in two colors. Diameter results for a fully darkened disk are 20.9 + or 2.0 milliarcsec at an effective wavelength of 7460 A and 18.4 + or 2.1 milliarcsec at an effective wavelength of 5680 A. Reappearance events were also obtained for several bright Hyades members, including a detection of the spectroscopic companion of theta-1 Tauri. Publication: The Astrophysical Journal Pub Date: March 1979 DOI: 10.1086/182914 Bibcode: 1979ApJ...228L.111B Keywords: Giant Stars; Lunar Occultation; Stellar Occultation; Binary Stars; Graphs (Charts); Stellar Spectrophotometry; Astronomy; Angular Diameters:K Stars; Hyades:Lunar Occultations; Lunar Occultations:Visual Binaries full text sources ADS |

Photoelectric observations of lunar occultations. X

Photoelectric observations of lunar occultations. X

OCCULTATIONS OF JUPITER SATELLITES.

ABSTRACT Observations of lunar occultations are presented for Callisto, Europa, and Ganymede. The resulting linear diameters are 4912 km, 3141 km, and 5062 km, respectively. The date of the events was 1977 January 1 (UT).

Angular Diameters of Cool Stars Measured by the Method of Lunar Occultations

Given the angular diameter and total energy flux of a star, its effective temperature can be determined. Until recently, there were few well-determined angular diameters of cool stars, and effective temperature calibrations rested on angular diameter measurements of several not necessarily “normal” stars. The number of measured angular diameters of stars cooler than about spectral type G is steadily being increased by using the method of photoelectric observations of lunar occultations.

Is the Earth contracting?

Summary. The fossil record of the vanation of the solar day and the synodic month with geological time is examined for evidence of the steady contraction of the Earth postulated by Lyttleton to explain a discrepancy between the apparent secular accelerations of the Sun and Moon. Data for the Phanerozoic and the Precambrian agree in showing that a change in the Earth's moment of inertia as large as that suggested by Lyttleton is only consistent with the fossil record if the secular change in the gravitational constant G/C 2 + 4 x 10-/yr. A variation of G of this magnitude appears to be ruled out by a recent analysis of lunar occultation observations utilizing Atomic Time. In a recent analysis of the apparent secular accelerations of the Sun and Moon Lyttleton (1976) has suggested that a discrepancy between observation and the predictions of tidal theory first noted by Jeffreys (1929) may be explained by a steady decrease in the Earth's moment of inertia i/Z = - 8 x lO-/yr. This observation lends support to the phasechange hypothesis (Ramsey 1948; Lyttleton 1965) in which the continued evolution of the Earth's liquid tore leads to a global contraction of order 0.1 mm/yr and a change in the moment of inertia consistent with that required to reconcile the astronomical observations. In this paper I shall discuss whether a contraction of the Earth of this magnitude is consistent with the lengths of the tropical year and the synodic month deduced from the growth patterns found in fossil bivalves, corals and stromatolites. I shall show that the fossil data probably rule out changes in the Earth's moment of inertia as large as those required to resolve the discrepancy between the lunar and solar accelerations.

Remarks on “Hipparchus's Solar Theory Derived from Lunar Eclipse Observations” by K. P. Moesgaard

Remarks on “Hipparchus's Solar Theory Derived from Lunar Eclipse Observations” by K. P. Moesgaard

Photoelectric observations of lunar occultations. IX

view Abstract Citations (28) References (9) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Photoelectric observations of lunar occultations. IX. Africano, J. L. ; Evans, D. S. ; Fekel, F. C. ; Montemayor, T. Abstract Observations of 223 occultation disappearances observed with a 30-in. telescope and five observed with a 36-in. telescope are reported. Instrument improvements are noted along with one new angular diameter (8.5 + or - 1.5 milliarcsec for HR 7023), one case of distortion of traces by the lunar limb, and a number of cases of stellar duplicity or multiplicity. In three instances it is possible to proceed to some double-star astrometry and astrophysics based on occultation and other observations. Publication: The Astronomical Journal Pub Date: August 1977 DOI: 10.1086/112097 Bibcode: 1977AJ.....82..631A Keywords: Binary Stars; Electrophotometry; Lunar Occultation; Astrometry; Astrophysics; Tables (Data); Ternary Systems; Astronomy full text sources ADS | Related Materials (15) Part 1: 1970AJ.....75..575N Part 2: 1970AJ.....75..583N Part 3: 1970AJ.....75..589E Part 4: 1970AJ.....75..963N Part 5: 1971AJ.....76.1107E Part 6: 1973AJ.....78..482D Part 7: 1975AJ.....80..689A Part 8: 1976AJ.....81..650A Part 10: 1978AJ.....83.1100A Part 11: 1980AJ.....85..478E Part 12: 1981AJ.....86.1277E Part 13: 1982AJ.....87.1571B Part 14: 1983AJ.....88.1845E Part 15: 1985AJ.....90.2360E Part 16: 1986AJ.....92.1210E

Lunar occultation observations of twelve 3C sources at 327 MHz

Lunar occultation observations of twelve 3C sources at 327 MHz

LUNAR OCCULTATIONS FROM CERRO TOLOLO. II. ANGULAR DIAMETERS FOR XI 2 SAGITTARII AND PI LEONIS.

ABSTRACT Observations of lunar occultations are presented for 2 Sgr and Leo. The resulting angular diameters for uniformly illuminated disks are 0,0037 and 0'.' 0052, respectively; and for fully limb-darkened disks, they are 0'.' 0042 and o': 0059, respectively. Key words: stellar diameter - lunar occultation

The Secular Decrease of Obliquity due to Dissipative Core--Mantle Coupling

Summary Aoki suggested, and later (Aoki; Kakuta & Aoki) presented a theoretical model in support of calculations, that frictional (electromagnetic or viscous) torques acting across the precessing Earth's core-mantle boundary could tilt the equator toward the ecliptic plane at an astronomically-detectable rate. An upper limit to any such rotation is set by the most recent analysis of lunar occultation observations by Duncombe & van Flandern which yields a discrepancy of no more than 0.01 f 0.05 cy-' between the observed secular rate of change of the obliquity and that due to calculated planetary perturbations of the ecliptic plane. This problem in the dynamics of the Earth's ortation is here re-examined, motivated by the shortcomings of Aoki's theory (principally the neglect of inertial fluid coupling between the core and mantle) and by the importance even so slow a geophysically-induced decrease of the obliquity would have for Earth-Moon history and galactic astronomy. An extension of PoincarBs model of a perfect liquid core inside a rigid mantle, allowing for the combined effects of inertial and dissipative coupling during precession, gives a rate of decrease of the obliquity 5 0~0004cy-', far below the level of detectability by current astronomical observations. Unless the actual value of the core viscosity approaches the upper limit of 10mZs-' set by Toomre, core-mantle coupling can be ignored in modelling the dynamical evolution of the Earth-Moon system. The relationship of this problem to that of the precession-driven geomagnetic dynamo is briefly discussed.

Is Gravity Getting Weaker?

Dirac's large-numbers hypothesis and Mach's principle of inertia which both predict that the strength of gravity decreases with time are discussed. Experiments to test this hypothesis such as observations of lunar occultations, lunar laser-ranging measurements and precise radar-ranging measurements are being carried out. Preliminary data indicate that the value of G is decreasing. One implication according to the large-numbers hypothesis is that the number of nucleons in the universe must be increasing at a rate proportional to the passage of time squared. A theory is proposed to account for this phenomena based on the hypothetical existence of a shield against gravity found only in very dense matter. Implications for the theories of special and general relativity are discussed. (BJG)

A Determination of the Rate of Change of G

Abstract : A new analysis of lunar occultation observations from 1955 to 1974 utilizing Atomic Time gives a value for the empirical part of the secular acceleration of the Moon's mean longitude of (- 65 plus or minus 18)/cy(2). This differs from other determinations which utilized the Ephemeris Time scale, based on the apparent annual motion of the Sun about the Earth. These latter, which give ( - 38 plus or minus 4)/cy(2), measure only the tidal component of the Moon's longitude acceleration. The remaining acceleration (- 27 plus or minus 18)/cy(2), has as its most probable cause a decrease in the Universal Gravitational Constant at the rate of G/G = (- 8 plus or minus 5) x 10(-11)/yr. There is a large body of supporting evidence for a rate of about this size, including the disappearance of the artificial' nontidal' component in the deceleration of the Earth's rotation, geophysical evidence for an observed expansion of the Earth's radius, and generally good agreement with recent determination of the Hubble constant, which is related to G/G. The observed rate is also consistent with the Dirac and the Hoyle-Narlikar cosmological theories, and to a lesser degree, with the Brans-Dicke theory. Other possible interpretations of the observed excess (negative) lunar acceleration are also discussed; but only those with cosmological significance seem at all plausible.