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1.
＜隋书．天文志＞天象记录选注 总被引：1，自引：1，他引：0
LIU CiYuan 《时间频率学报》1996,(1)
以占卜为主要目的的天象记录在中国历代官定史书中占有重要位置，同时也是读史者的障碍．现代天文方法可以推算有史以来的大多数天象记录．这些计算结果与古代记录比对，可借以校正文字，考察古人的观测方法和制度，体验其星占心态，对历代天文志中占主要篇幅的天象记录有一个较深刻的认识．作为例子，本文计算了＜隋书＞天文志中梁、陈两代六十余年的天象记录，并与其它史籍中的有关记载作了比对和考校．对文中涉及的天象也尽可能作出科学的解释． 相似文献
2.
中国最早的观象台发掘 总被引：2，自引：1，他引：1
在山西襄汾县陶寺镇附近发掘出距今约4000年的最早观象台兼祭祀台遗址,它是由观测点、夯土柱和柱间狭缝组成,用于观测日出方位变化,确定回归年长度来制订历法。模拟观测结果表明,位于东南和东北的二狭缝可准确测定冬至和夏至日期,而此二狭缝之间有10个土柱,应象征着视太阳向北和向南每位移一个土柱为一个节气。由此推之,帝尧时的历法特征是将一岁分成20个节气的阳历,上古时的阴阳五行历即十月太阳历是源于它奠定的基础。 相似文献
3.
The Apollo-12 ALSEP solar wind spectrometer obtained data from the lunar surface starting November 20, 1969. To a first approximation, the general features of the positive ion flux depend only on the instrument's orientation and location in space relative to the Sun-Earth system. However, there are some detectable effects of the interaction of the solar wind with the local magnetic field and surface, including the deceleration of incident positive ions and the enhancement of fluctuations in the plasma. The expected asymmetry of sunset and sunrise times due to the motion of the Moon about the Sun is not observed. On one occasion, the solar wind was incident on the ALSEP site as early as 36 hr (18°) before sunrise. 相似文献
4.
古代文献记载帝尧时的历法存在两种不同说法。羲和观测四仲中星定季节当是不实之辞,并以闰月成岁推论为使用农历也没依据。羲和观测太阳出没方位变化而"生十日"、即制订产生十月太阳历才符合事实。在文[1]中的推论,也与后一种说法可互相印证。本文对文[1]的推论作出了论据补充,与文[1]成姐妹篇。 相似文献
5.
《Planetary and Space Science》1987,35(8):1053-1059
Whistler-mode signals were measured at the conjugate point (L = 1.93) in South Australia of the VLF transmitter in Eastern U.S.S.R. The intensity of whistler-mode signals increased usually at sunset and occasionally at sunrise, and was moderate during night-time. By means of the calculation of the wave attenuation in the lower ionosphere, the result may be interpreted in terms of different mechanisms of propagation in the magnetosphere and transmission out of the ionosphere: spatially coherent propagation in a field-aligned duct and transmission out of the duet onto the ground at sunset and sunrise; and spatially incoherent propagation and transmission at night. A high correlation was found between the occurrence probability of the 14.881 kHz whistler-mode signals and the occurrence number of whistlers, which may suggest that the occurrence of whistlers is controlled predominantly by propagation conditions. 相似文献
6.
A magnetic type mass spectrometer has been flown on two ESRO sounding rockets from ESRANGE (Kiruna 68°N) on February 25 and 26, 1970. The first launch was at sunset (16:33 UT) and the second the next morning, during sunrise (04:47 UT). For both flights the solar zenith angle was approximately 98°. The instrument was measuring simultaneously the neutral gas and positive ion composition and the total ion density. In this paper the results of the ion composition measurements are presented. For both flights the main ion constituents measured between approximately 110–220 km were O+, NO+ and O2+. Only at sunset were N+ and N2+ detected above 200 km. In spite of the identical solar UV-radiation, pronounced sunset/sunrise variations in the positive ion composition were found. The total ion densities at sunrise were between 5×103 and 5 × 104 ions cm?3 and therefore too high to be explained without a night-time ionization by precipitated particles. At sunrise the NO+ and O2+ profiles show a correlated wavelike structure with three pronounced almost equally spaced layers in the E-region. Only the highest layer is present in the O+ profile. Locally enhanced field aligned ionization originated by particle precipitation and an E × B instability are the most likely source for this structure. In the E- and lower F-regions the ration increased overnight from values around 7 at sunset to 15 at sunrise, correlated with an increase of the local magnetic activity index K from 0+ to 2°. This could be explained if the NO density and magnetic activity are correlated. 相似文献
7.
元代郭守敬等1280年编制的《授时历》是中国本土科学家研制的最后一部历法,具有极高的精度。采用其仍可预报2012年5月21日发生的日食,其预报北京地区的见食情况时食甚时刻误差4 min,食分误差为0.04。给出了《授时历》推步的1990～2050年北京的见食情况及精度,其中食甚时刻的标准偏差为103.04 min,食分的标准偏差则不低于0.33。通过考察1280～2050年间186个日食计算结果,可得出《授时历》自行用以来推步日食的误差,考虑到存在错报(不可见)和漏报因素的影响,其食甚时刻和食分的标准偏差分别不低于50.65 min和0.19;同时指出,随着行用时间的延长其推时误差也逐步放大。 相似文献
8.
Constantinos I. Cartalis 《Earth, Moon, and Planets》1991,52(2):131-144
A new method is developed to determine the concentration profiles of chemical species from satellite measurements. The method takes into account the interaction of photochemical and radiative processes in the stratosphere and is applied for chemical species (nitric oxide and nitrogen dioxide) experiencing large diurnal changes. It is found that if the interaction of the photochemical and radiative processes is neglected, that is if the temporal and spatial variations of NO and NO2 are not considered in the radiative transfer calculations, the resulting errors for the concentration profiles for altitudes less than 20 km reach 100 and 5% respectively, for both sunset and sunrise. A photochemical scheme is developed capable of providing the mixing ratio profiles of NO and NO2 for different latitudes, altitudes and seasons and a retrieval code combining an iterative inversion algorithm, working from top of the atmosphere downwards, and a parameterization of the variability of NO and NO2 is also constructed. The method is used to examine the accuracy of the retrieval of the vertical concentration profiles and the new results show that the recovered profiles are in good agreement (error 5–15%) with measured profiles (WMO, 1985) and reflect the trends of NO and NO2 at sunset and sunrise. 相似文献
9.
10.
Xue-Feng Zhang Ruo-Yin DuSheng-Min Gu Tong WuYou-Ning Wang 《Chinese Astronomy and Astrophysics》2011,35(1):54
Using the sudden ionospheric disturbance (SID) monitor provided by the Stanford University, the very low frequency (VLF) signals were observed in Nanjing during the total solar eclipse on 22nd July 2009. It is found that the intensity of the VLF signal varied anomalously during the total solar eclipse, exhibiting the effect similar to the sunrise and sunset, and that the intensity of the VLF signal strongly fluctuated, exhibiting the effect similar to thunderbolts. Moreover, the signal intensity enhanced in short periods both before and after the total eclipse. Based on the discussion on the reliability of the observed data and the comparison with the previous observations, it is found that the ionosphere exhibits some variations previous to the total solar eclipse. 相似文献
11.
L.H. Wasserman 《Icarus》1974,22(1):105-110
The nightime cooling of the Jovian atmosphere near the occulation level of 1014cm?3 is calculated using the models of Strobel (1973) and Strobel and Smith (1973). The amount of cooling is found to depend on χ, the methane mixing ratio; μ the mean molecular weight; and the sunrise temperature. Using the range of sunrise (emersion) temperatures observed by Veverka et al. (1974), the overnight cooling is calculated to be 1.5–5.5°K, if reasonable assumptions are made for χ and μ. The argument may be reversed to show that the agreement in measured sunrise and sunset temperatures obtained by other observers of the β Sco occulation implies that χ cannot be significantly greater than the generally accepted value of 7 ×10?4. 相似文献
12.
A reanalysis of the Apollo light scattering observations, and implications for lunar exospheric dust
David A. Glenar Timothy J. Stubbs James E. McCoy Richard R. Vondrak 《Planetary and Space Science》2011,59(14):1695-1707
Conspicuous excess brightness, exceeding that expected from coronal and zodiacal light (CZL), was observed above the lunar horizon in the Apollo 15 coronal photographic sequence acquired immediately after orbital sunset (surface sunrise). This excess brightness systematically faded as the Command Module moved farther into shadow, eventually becoming indistinguishable from the CZL background. These observations have previously been attributed to scattering by ultrafine dust grains (radius ∼0.1 microns) in the lunar exosphere, and used to obtain coarse estimates of dust concentration at several altitudes and an order-of-magnitude estimate of ∼10−9 g cm−2 for the column mass of dust near the terminator, collectively referred to as model “0”.We have reanalyzed the Apollo 15 orbital sunset sequence by incorporating the known sightline geometries in a Mie-scattering simulation code, and then inverting the measured intensities to retrieve exospheric dust concentration as a function of altitude and distance from the terminator. Results are presented in terms of monodisperse (single grain size) dust distributions. For a grain radius of 0.10 microns, our retrieved dust concentration near the terminator (∼0.010 cm−3) is in agreement with model “0” at z=10 km, as is the dust column mass (∼3–6×10−10 g cm−2), but the present results indicate generally larger dust scale heights, and much lower concentrations near 1 km (<0.08 cm−3 vs. a few times 0.1 cm−3 for model “0"). The concentration of dust at high altitudes (z>50 km) is virtually unconstrained by the measurements. The dust exosphere extends into shadow a distance somewhere between 100 and 200 km from the terminator, depending on the uncertain contribution of CZL to the total brightness. These refined estimates of the distribution and concentration of exospheric dust above the lunar sunrise terminator should place new and more rigorous constraints on exospheric dust transport models, as well as provide valuable support for upcoming missions such as the Lunar Atmosphere and Dust Environment Explorer (LADEE). 相似文献
13.
K.W. Lee 《Astronomische Nachrichten》2012,333(7):648-659
The historical documents of ancient Korea contain abundant records on various astronomical phenomena. The historical documents of the Joseon dynasty contain observational values based on Chinese equatorial coordinate system (i.e., angular distances from the reference star of a lunar mansion and the North Pole). However, quantitative analysis of the observational values has not been carried out. In this study, we investigate the observational accuracy during the Joseon dynasty by comparing the astronomical records of Joseonwangjo Sillok (Annals of the Joseon Dynasty) and Seungjeongwon Ilgi (Daily Records of the Royal Secretariat) with modern astronomical calculations. Consequently, we find that the observational accuracy during the early Joseon dynasty was approximately 1°.2 and 0°.3 in the right ascension and declination, respectively. On the other hand, we find that the observational accuracy during the later Joseon dynasty was considerably poor. Observations of Halley's comet in 1759 were off by approximately 7° in declination. We believe that further investigation is required to verify the reason for this poor accuracy. Thus, we list the complete records used for this study in the appendix. We believe that these records also can contribute to modern studies on phenomena such as supernovae or Halley's comet. In conclusion, we believe that this study is useful for understanding ancient Korean astronomical records, even though we have considered a small number of astronomical events (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
14.
Leslie Hebb Larry Petro Holland C. Ford David R. Ardila Ignacio Toledo Dante Minniti David A. Golimowski Mark Clampin 《Monthly notices of the Royal Astronomical Society》2007,379(1):63-72
We present high-cadence, high-precision multiband photometry of the young, M1Ve, debris disc star, AU Microscopii. The data were obtained in three continuum filters spanning a wavelength range from 4500 to 6600 Å, plus Hα, over 28 nights in 2005. The light curves show intrinsic stellar variability due to star-spots with an amplitude in the blue band of 0.051 mag and a period of 4.847 d. In addition, three large flares were detected in the data which all occur near the minimum brightness of the star. We remove the intrinsic stellar variability and combine the light curves of all the filters in order to search for transits by possible planetary companions orbiting in the plane of the nearly edge-on debris disc. The combined final light curve has a sampling of 0.35 min and a standard deviation of 6.8 mmag. We performed Monte Carlo simulations by adding fake transits to the observed light curve and find with 95 per cent significance that there are no Jupiter mass planets orbiting in the plane of the debris disc on circular orbits with periods, P ≤ 5 d. In addition, there are no young Neptune like planets (with radii 2.5 times smaller than the young Jupiter) on circular orbits with periods, P ≤ 3 d. 相似文献
15.
E. Van Hemelrijck 《Earth, Moon, and Planets》1983,29(1):83-93
This paper describes variations in the insolation on Mercury resulting from fluctuations of the orbital eccentricity (0.11≤e≤0.24) of the planet. Equations for the instantaneous and the daily insolation are briefly discussed and several numerical examples are given illustrating the sensitivity of the solar radiation to changes ine. Special attention is paid to the behavior of the solar radiation distribution curves near sunrise and sunset which at the warm pole of Mercury (longitudes ±90°) occur as the planet goes through perihelion. It has been found that for eccentricities larger than about 0.194 there exists two permanent thermal bulges on opposite sides of the Mercurian surface that alternately point to the Sun at every perihelion passage. The critical value ofe past which the Sun shortly sets after perihelion is near 0.213. 相似文献
16.
Solar electromagnetic radiation of wavelengths ranging from 260–1300 Å was measured by a grazing-incidence grating spectrometer on OSO-III, which operated as a monochromator with a wavelength bandwidth of about 2 Å and an acceptance angle covering the whole disk without any instrumental discrimination of source locations. The monochromator was commanded either to scan the whole spectrum or to operate at variously chosen fixed wavelengths. The latter mode of operation afforded a high-time resolution in the observation of temporal variations such as those associated with solar flares, and also allowed accurate determinations of the absorption characteristic of the earth's upper atmosphere (near sunset and sunrise). 相似文献
17.
Dmitri I. Ponyavin 《Solar physics》2004,224(1-2):465-471
Historical geomagnetic and climate records were analyzed to study long-term trends and relationships with solar activity.
Wavelet technique and recurrence plot analysis are applied to the data to find their coherence and similarities at different
times and time-scales. It is shown that the solar cycle signal is more pronounced in climatic data during the last 60 years. 相似文献
18.
Brian J. O'Brien 《Planetary and Space Science》2011,59(14):1708-1726
This is the first review of 3 Apollo experiments, which made the only direct measurements of dust on the lunar surface: (i) minimalist matchbox-sized 270 g Dust Detector Experiments (DDEs) of Apollo 11, 12, 14 and 15, produced 30 million Lunar Day measurements 21 July 1969–30 September, 1977; (ii) Thermal Degradation Samples (TDS) of Apollo 14, sprinkled with dust, photographed, taken back to Earth into quarantine and lost; and (iii) the 7.5 kg Lunar Ejecta and Meteoroids (LEAM) experiment of Apollo 17, whose original tapes and plots are lost. LEAM, designed to measure rare impacts of cosmic dust, registered scores of events each lunation most frequently around sunrise and sunset. LEAM data are accepted as caused by heavily-charged particles of lunar dust at speeds of <100 m/s, stimulating theoretical models of transporting lunar dust and adding significant motivation for returning to the Moon. New analyses here show some raw data are sporadic bursts of 1, 2, 3 or more events within time bubbles smaller than 0.6 s, not predicted by theoretical dust models but consistent with noise bits caused by electromagnetic interference (EMI) from switching of large currents in the Apollo 17 Lunar Surface Experiment Package (ALSEP), as occurred in pre-flight LEAM-acceptance tests. On the Moon switching is most common around sunrise and sunset in a dozen heavy-duty heaters essential for operational survival during 350 h of lunar night temperatures of minus 170 °C. Another four otherwise unexplained features of LEAM data are consistent with the “noise bits” hypothesis. Discoveries with DDE and TDS reported in 1970 and 1971, though overlooked, and extensive DDE discoveries in 2009 revealed strengths of adhesive and cohesive forces of lunar dust. Rocket exhaust gases during Lunar Module (LM) ascent caused dust and debris to (i) contaminate instruments 17 m distant (Apollo 11) as expected, and (ii) unexpectedly cleanse Apollo hardware 130 m (Apollo 12) and 180 m (Apollo 14) from LM. TDS photos uniquely document in situ cohesion of dust particles and their adhesion to 12 different test surfaces. This review finds the entire TDS experiment was contaminated, being inside the aura of outgassing from astronaut Alan Shepard's spacesuit, and applies an unprecedented caveat to all TDS discoveries. Published and further analyses of Apollo DDE, TDS and LEAM measurements can provide evidence-based guidance to theoretical analyses and to management and mitigation of major problems from sticky dust, and thus help optimise future lunar and asteroid missions, manned and robotic. 相似文献
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20.
中国古代太阳中天观测及二至点测算精度 总被引：1，自引：0，他引：1
研究了元代《授时历议))所保存的天象观测和推步资料，得出：(1)在AD1277—1280年问所作的98次太阳中天观测的时刻及地平高度的绝对值平均误差分别为2．64min和6．78′．(2)6部古历——《大衍历》、《宣明历》、《纪元历》、《统天历》、《重修大明历》和《授时历》推步BC522年前的3个冬至时刻的误差范围为0．97—3．51d；而AD435—1280年间的45个冬至时刻的绝对值平均误差则分别为9．35、10．42、5．54、2．97、5．68、3．36h．(3)古代确定的AD442—1280年间的16个二至时刻的绝对值平均误差为199．59min，其中元代的误差为27．89min． 相似文献