1980年2月16日日全食昆明色球掩食观测

本文提供了八○年二月十六日在昆明观测到的太阳色球层的日全食掩食过程。文中给出太阳可见面上各活动对象(包括黑子、谱斑、暗条、日珥等)的月掩时间,它们是射电观测、电离层观测以及日全食各项光学观测资料分析研究的重要依据。     

1968年9月22日日食射电观测

本文综合分析了1968年9月22日新疆日全食3.2、11.1和21厘米波长的射电观测资料,得出了射电源的流量和活动区活动性的关系、射电源辐射与谱斑及黑子的相关等观测结果。另外,从综合三个波段的资料通盘考虑了射电源流量值的误差分析、射电源的角径和高度、射电食甚、射电太阳等效半径和日面小爆发等。     

太阳射电辐射的第四种成份——太阳射电快变分量

太阳射电天文学从1942年诞生到现在,人们已经观测到并证实了的太阳射电基本辐射成份有三种:它们是太阳射电爆发分量、太阳射电缓变分量和太阳射电宁静分量。 本文报导的是,在经过太阳活动22周峰年的国内联合观测以及参加Fares22和Max’91 Compaign国际联合观测中,我们已经观测到并从大量观测资料中证实了的是,太阳上存在有第四种射电辐射成份——太阳射电快速变化分量。     

1980年2月16日日全食在波长8.2厘米的射电观测

1980年2月16日日全食带经过云南天文台,本台的8.2厘米射电望远镜进行了观测,获得了预期的观测结果.本文对观测资料进行了处理,分析了射电局部源和光学活动的对应关系,得出了15个射电源的流量、一维角径大小、高度和亮温度.计算出谱斑上空晕的辐射标度N~2L=5.3×10~(28)电子数~2/厘米~5.     

日食的射电观测(英)

日食为射电天文提供了一维高空间分辨率太阳射电观测机会．日食射电观测在太阳射电物理的发展上起过重要的作用．文中对日食射电观测的若干重要因素作了介绍和分析．日食射电观测在我国太阳射电天文发展上也起了重要作用．文中简要介绍了在我国组织观测的1958年、1968年、1980年及1987年的太阳射电日食观测及其主要结果．     

日食的射电观测

日食为射电天文提供了一维高空间分辨率太阳射电观测机会,日食射电观测在太阳射电物理的发展上起过重要的作用,文中对日食射电观测的若干重要因素作了介绍和分析,日食射电观测在我国太阳射电天文台发展上也起了重要作用,文中简要介绍了在我国组织观测的１９５８年,１９６８年,１９８０年及１９８７年太阳射电日食观测及其主要结果。     

太阳低频射电干涉阵的构建仿真

介绍了低频射电干涉阵的发展情况、研究领域,讨论了国际上的LOFAR、LWA和MWA等低频射电项目.借鉴当今的低频射电项目,结合云南的地理和太阳射电优势,设想在云南省内构建一个太阳低频射电干涉阵,观测频率在30 MHz～250 MHz范围内,文中仿真了太阳低频射电干涉阵(4台站),比较和分析了通过优化算法得到的阵列的UV覆盖、脏束(Dirty beam);讨论了低频射电干涉阵的观测模式、射电干扰、低频射电成像等问题;分析低频射电阵在观测太阳爆发性活动产生的日冕物质抛射(Coronal Mass Ejections,CME)、耀斑、射电爆发的可能性;通过上述的仿真和分析构建太阳低频射电干涉阵面临的问题,可以为今后建立阵列提供依据.     

1997年3月9日日全食8.6mm波段射电观测

１９９７年３月９日日全食８．６ｍｍ波段射电观测资料的分析表明,８．６ｍｍ波段射电太阳的半径为１．０１２Ｒ,总流量为２５４０ｓｆｕ（１ｓｆｕ＝１０＾－２２Ｗ／ｍ＾２Ｈｚ）,日面平均亮温度为９６３２Ｋ,径向亮温度分布,在日面光学边缘内侧０．９３６－０．９９２Ｒ处,存在临边增亮,平均增亮幅度相对于日面中心为９．７％。     

1997年3月9日日全食8.6mm波段射电观测

１９９７年３月９日日全食８．６ｍｍ波段射电观测资料的分析表明：８．６ｍｍ波段射电太阳的半径为１．０１２Ｒ,总流量为２５４０ｓｆｕ（１ｓｆｕ＝１０－２２Ｗ／ｍ２Ｈｚ）,日面平均亮温度为９６３２Ｋ,径向亮温度分布,在日面光学边缘内侧０．９３６－０．９９２Ｒ处,存在临边增亮,平均增亮幅度相对于日面中心为９．７％．     

太阳耀斑中的射电漂移结构

结合紫金山天文台的太阳射电观测资料,对太阳耀斑中的射电漂移结构进行研究。过去的观测发现,漂移结构太阳耀斑产生的射电爆发伴随一种特殊的结构。观测特征是其中的细结构是由许多小脉冲组成,但整体随时间漂移。过去观测到的这种结构是向低频漂移。观测上他们与太阳耀斑中的等离子团抛射相对应。2003年3月18日,紫金山天文台射电频谱仪观测到的漂移结构是漂向高频。     

Cassini/VIMS observation of an Io post-eclipse brightening event

During the Cassini-Jupiter flyby, VIMS observed Io at different phase angles, both in full sunlight and in eclipse. By using the sunlight measurements, we were able to produce phase curves in the visual through all the near infrared wavelengths covered by the VIMS instrument (0.85-5.1 μm). The phase angle spanned from ∼2° to ∼120°. The measurements, done just after Io emerged from Jupiter's shadow, show an increase of about 15% in Io's reflectance with respect to what would be predicted by the phase curve. This behavior is observed at wavelengths >1.2 μm. Moreover, just after emergence from eclipse an increase of about 25% is observed in the depth of SO₂ frost bands at 4.07 and 4.35 μm. At 0.879<λ<1.04 μm the brightening is 10-24%. Below λ=0.879 μm the brightening, if present, should be less than the precision of our measurements (∼5%). Apparently, these observations are not explained neither by a diverse spatial distribution of SO₂ on the Io' surface nor by atmospheric SO₂ condensation on the surface during the eclipse.     

Observations of the 7 March, 1970 total solar eclipse at wavelengths of 3.2 and 8.3 mm

The 7 March, 1970 total solar eclipse was observed at wavelengths of 3.2 and 8.3 mm; the object being to use the knife edge of the Moon as it passed across the Sun to improve angular resolution on the Sun. This in turn would provide a radial brightness distribution of the Sun with an angular resolution of a few seconds of arc.Excellent eclipse curves were obtained at 3 mm; however, some external interference marred the 8 mm record near totality.The 8 mm brightness distribution is subject to some uncertainty, but tends to show limb brightening. The 3 mm brightness distribution shows a well defined complex limb brightening within about 1 arc min of the optical limb. The maximum brightening is approximately 30% above the average disc temperature.     

Solar eclipse observations of a magnetic loop structure at 2, 3.2, 8.2 and 21 cm

During the total eclipse of 1980 February 16, eclipse slope curves at 2, 3.2, 8.2 and 21 cm were obtained as the Moon occulted an active region with a bipolar sunspot group. From the peaks in these curves and the heights of the effective emission layers, the cores of the radio sources at the four wavelengths are located. Connecting these sites gives a magnetic loop structure. Relations between the locations, sizes, fluxes of the radio sources and the intensities, extensions, sizes and shapes of the bipolar sunspot field are analysed. The result at 8.2 cm is similar to the loop structure observed with the VLA at 6 cm. The radio flux spectrum shows that the gyro-radiation dominates over the thermal bremsstrahlung in this active region.     

Computation of the atmosphere-less light intensity curve during a total solar eclipse by using Lunar Reconnaissance Orbiter topography data and the DE430 astronomical ephemeris

Observations of the sky irradiation intensity in the visible wavelengths during a solar eclipse permit to model the Sun diameter,a key number to constrain the internal structure of our star.In this paper,we present an algorithm that takes advantage of the precise Moon topography from Lunar Reconnaissance Orbiter to compute,with a high resolution in time,the geometrical part(i.e.top-of-atmosphere,and for a given wavelength)of the sky irradiation at any given location on the Earth during these events.The algorithm is also able to model the Baily’s beads.We give as an application the theoretical computation of the light curve corresponding to the solar eclipse observed at Lakeland(Queensland,North Australia)on 2012 November 13.The application to real data,with the introduction of atmospheric and instrumental passbands,will be considered in a forthcoming paper.     

Variation of Spectral Radiance of the Zenith Sky During the Annular Eclipse on May 21, 2012

The absolute brightness of the zenith sky was measured using a simple calibrated spectrometer during the annular solar eclipse event on May 21, 2012 in Fujioka City, Japan (36.2924°N, 139.0823°E). The sensitivity of the spectrometer was calibrated as a function of wavelength between 400 and 700 nm with an integral sphere. The brightness of the sky decreased to 6 % of its usual condition at the maximum magnitude of the annular eclipse of 0.95 for all wavelengths. The curve describing the variation of sky brightness accords well with the total luminosity of the solar disk estimated by a simple model that accounts for the limb darkening effect. This study provides zenith sky radiance as a function of wavelength and solar elevation angle, which is useful for the investigation of new optical instruments for atmospheric studies.     

Limb darkening in the solar ultraviolet

New photoelectric limb-darkening data are given for 38 of the windows in the UV solar spectrum in which Houtgast has supplied absolute energy measurements. The region, 4000 Å to 3000 Å, is marked by unaccounted opacity. Results are given also for 13 longer wavelengths. The measurements are fully corrected for atmospheric seeing and scattering. The corrected drift curves exhibit a quasi-periodic character suggestive of the supergranulation.     

Radio emission from the quiet sun and local sources at wavelengths 5, 10.7, 12, and 95 cm from observations of the January 4, 2011 eclipse in Crimea

The radio radii of the Sun at wavelengths of 5, 10.7, 12, and 95 cm have been determined from eclipse observations as R₅ ?? (1.0 ± 0.015)R _??, R _10,12 = (1.05 ± 0.003)R _??, and R ₉₅ = (1.2 ± 0.02)R _??. The bright-ness temperatures of quiet solar disk areas at these wavelengths have turned out to be Td ₅ = (22 ± 2) × 10³, Td ₁₀ = (44 ± 3) × 10³, Td ₁₂ = (47 ± 3) × 10³, and Td ₉₅ = (1000 ± 30) × 10³ K. There were local sources of radio emission with angular sizes from 1.9 to 2.4 arcmin and brightness temperatures from 80 × 10³ to 1.75 × 10⁶ K above sunspot groups at short wavelengths of 5, 10.7, and 12 cm. The radio flux from the local sources at 95 cm turned out to be below the detection threshold of 1.0 × 10^?22 W m^?2 Hz^?1. Comparison of the values obtained with the results of observations of another eclipse on August 1, 2008, occurred at the epoch of minimum of the 11-year solar cycle has shown that the radio radius of the Sun at 10.7 and 12 cm increased from 1.016 R _?? to 1.05 ± 0.003R _??, the height of the emitting layer at these wavelengths moved from 11 × 10³ km to (30 ± 7) × 10³ K, and the brightness temperature of the quiet Sun rose from (35.8 ± 0.4) × 10³ K to (44 ± 3) × 10³ K at 10.7 cm and from (37.3 ± 0.4) × 10³ K to (47 ± 3) × 10³ K at 12 cm. Consequently, the parameters of the solar atmosphere changed noticeably in 2 years in connection with the beginning of the new solar cycle 24. The almost complete absence of local sources at the longest wavelength of 95 cm suggests that the magnetic fields of the sunspot groups on January 4, 2011, were weak and did not penetrate to the height from where their emission could originate. If this property is inherent in most sunspot groups of cycle 24, then it can be responsible for its low flare activity.     

Radio observations of the 1968 September solar eclipse

This paper summarizes the analysis of the radio observations of the solar eclipse at wavelengths 3.2, 11.1 and 21 cm in Xinjiang, on 1968 Sept. 22. From the observations, we have determined the flux densities, angular diameters and heights of the localized radio sources on the solar disk, circumstances of the radio eclipse, equivalent radius of the radio Sun and certain features of a small radio burst that occurred during the eclipse. We have also investigated the correlation between the flux density of the localized sources and the activity of the active regions, as measured by the integrated brightness of plages and the sunspot area.     

Cassini-VIMS at Jupiter: solar occultation measurements using Io

We report unusual and somewhat unexpected observations of the jovian satellite Io, showing strong methane absorption bands. These observations were made by the Cassini VIMS experiment during the Jupiter flyby of December/January 2000/2001. The explanation is straightforward: Entering or exiting from Jupiter's shadow during an eclipse, Io is illuminated by solar light which has transited the atmosphere of Jupiter. This light, therefore becomes imprinted with the spectral signature of Jupiter's upper atmosphere, which includes strong atmospheric methane absorption bands. Intercepting solar light refracted by the jovian atmosphere, Io essentially becomes a “mirror” for solar occultation events of Jupiter. The thickness of the layer where refracted solar light is observed is so large (more than 3000 km at Io's orbit), that we can foresee a nearly continuous multi-year period of similar events at Saturn, utilizing the large and bright ring system. During Cassini's 4-year nominal mission, this probing technique should reveal information of Saturn's atmosphere over a large range of southern latitudes and times.     

The radial brightness distribution of the Sun at 3.2 mm as determined from the June 30, 1973 total solar eclipse and a reanalysis of the March 7, 1970 total solar eclipse

The radial brightness distribution of the Sun at 3.2 mm is recalculated for the 7 March, 1970 total solar eclipse by an improved method. The results from the first contact of the 30 June, 1973 total eclipse are also analyzed. Limb brightening is apparent for the 1970 eclipse when all four contacts are averaged. The 1973 eclipse indicates strong limb brightening, although the detailed shape differs from the 1970 eclipse.