共查询到20条相似文献,搜索用时 93 毫秒
1.
1996年1月~1998年3月,我们用光电方法测定了丽江高美古在B、V两个波段的大气消光系数。为便于比较,在1996年1月还测定了云南天文台凤凰山台址的大气消光系数。本文给出了观测结果,同时也列出了世界上一些天文台站的数据以供参考。 相似文献
2.
1996年1月 ̄1998年3月,我们用光电方法测定了丽江高美古在B、V两个波段的大气消光系数。为便于比较,在1996年1月还测定了云南天文台凤凰山台址的大气消光系数。本文给出了观测结果,同时也列出了世界上一些天文台站的数据以供参考。 相似文献
3.
4.
5.
6.
大气消光系数的测定是天文观测台站一项很重要和基础的工作.介绍了利用新建的2.4 m望远镜在高美古观测站开展的消光系数测定等定标工作的初步结果.利用2009年4~5月对Landolt标准星场的2次测光观测,分别给出了UBVRI 5个波段的消光系数.此外,对该站点大气消光的成分情况进行了探讨.给出的结果与数年前高美古观测站选址时得到的大气消光系数基本一致,并与其它一些知名天文观测台站的消光数据进行了比较. 相似文献
7.
8.
差分像运动视宁度测量实验 总被引:1,自引:0,他引:1
本文首先阐明了Fried参数(大气相干长度)r0的物理含义及为什么选取r0作为表征大气视宁度的参数;然后介绍了一种优良的测量r0的方法-差分像运动法,总结了该方法的六个特点,最后给出了在云南天文台用该方法的六个特点,最后给出了在云南天文台用该方法两次实测大气视宁度的实验结果及实验参数,并对结果进行了分析。 相似文献
9.
10.
11.
On the basis of exact computations of the extinction efficiencies of spheroidal absorbing particles, numerical calculations of the extinction curves have been made for a distribution of particle sizes. The results are presented and compared with the observed interstellar extinction. For the sake of comparison, results for the nonabsorbing particles are also given. 相似文献
12.
Atmospheric densities have been deduced from high resolution radar-determined orbital decay data and from data obtained from a uniaxial accelerometer flown onboard the low altitude satellite 1970-48A. Data were obtained during late June and early July, 1970. The orbital decay-deduced densities, having an effective 6 hr temporal resolution, were determined at an altitude of 143 km, essentially one-half scale height above perigee. The accelerometer deduced densities at the same altitude were obtained on both the approaching-perigee and leaving-perigee portions of each of fifty-nine orbits. A detailed comparison of the densities derived from both types of data is presented. In general, agreement is very good. A comparison of both types of data has also been made with the Jacchia 1970 and 1971 atmospheric models as well as the new OGO-6 atmospheric model. The Jacchia models display reasonable agreement with the data, but the OGO-6 model is unsuitable as a representation of atmospheric density at this altitude. 相似文献
13.
A comparison is made between the plane-parallel approximation and the more realistic spherical shell approximation for the radiance reflected from a planetary atmosphere. In this paper we have considered a planet of radius 6371 km (the Earth) with a homogeneous, conservative, Rayleigh scattering atmosphere extending to a height of 100 km. We have found significant departures from the plane-parallel approximation. Radiance versus height distributions for both single and multiple scattering are presented. Results are presented for the fractional radiance from altitudes in the atmosphere which contribute to the total unidirectional reflected radiance at the top of the atmosphere. We have referred to this as the radiance versus height distribution in the sequel. These data will be very useful for both remote sensing applications and planetary spectroscopy. We have also found that gross violations of the principle of reciprocity do occur in the spherical shell approximation. 相似文献
14.
《Physics and Chemistry of the Earth, Part C: Solar, Terrestrial & Planetary Science》1999,24(4):305-310
Target ranging by HF radar can be done by correcting the group path of target echoes for the delay due to the propagation through the ionosphere. One possibility is to simulate the propagation by ray-tracing but in this case the final accuracy obtained in target registration depends mainly on the quality of the ionospheric model used to raytrace. In this study, the PRIME ionospheric model has been used to perform ray-tracing on a 950 km path, between Toulon and Lannion, for which oblique soundings data from the SCIPION sounder are available for December 1991. The ray-tracings were performed by using the vertical electron density profiles at five points along the path calculated by PRIME for monthly median and/or instantaneous conditions. Vertical electron density profiles from the IRI model have also been considered for comparison. The results of this investigation are presented and the accuracy in target ranging is discussed as obtained for the conditions of the simulations. 相似文献
15.
T. P. Kiseleva I. S. Izmailov O. A. Kalinichenko T. A. Vasilieva 《Solar System Research》2010,44(1):60-67
The results of the reduction, investigation, and comparison of the photographic observations of the major Saturnian satellites
and CCD observations with an ST6 CCD camera obtained at the 264nch Pulkovo refractor in 1995–2007 are presented. A comparison
of the observational results with the TASS 1.7 theory of motion of the Saturnian satellites has served as the basis for investigating
and comparing the series of observations. The period-averaged (O-C) residuals and observational errors have been calculated.
A comparison of the series of CCD and photographic observations has shown the same external accuracy of the observations at
a higher internal accuracy of the CCD observations than that of the photographic ones. A comparison of the Pulkovo results
with those of other authors has shown them to be close in accuracy. The accuracy of the theory has been estimated by comparing
simultaneous (on the same night) CCD and photographic observations. The errors of the observations and the theory have been
found from this comparison to be the following: 0.081“ and 0.067” for the observations and 0.077“ and 0.115” for the theory
(inxandy, respectively). An analysis of the dependence of (O-C)x,y for three satellites (the sixth, seventh, and eighth) on the satellite positions in Saturn-centered orbits has revealed systemat
ic deviations for the seventh satellite in both coordinates. The positions of Saturn have been determined from satellite observations
without measuring its images on photographic plates with accuracies of 0.121“ and 0.105” in right ascension and declination,
respectively. 相似文献
16.
S. K. Ghosh B. Mookerjea T. N. Rengarajan S. N. Tandon R. P. Verma 《Journal of Astrophysics and Astronomy》2001,22(2-3):173-185
Three Galactic star forming regions associated with W3(OH), S209 and S187 have been simultaneously mapped in two trans-IRAS
far infrared (FIR) bands centered at ≈140 and 200μm using the TIFR 100 cm balloon borne FIR telescope. These maps show extended
FIR emission with structures. The HIRES processed IRAS maps of these regions at 12, 25, 60 & 100 ìm have also been presented
for comparison. Point-like sources have been extracted from the longest waveband TIFR maps and searched for associations in
the other five bands. The diffuse emission from these regions have been quantified, which turns out to be a significant fraction
of the total emission. The spatial distribution of cold dust (T < 30 K) for two of these sources (W3(OH) & S209), has been
determined reliably from the maps in TIFR bands. The dust temperature and optical depth maps show complex morphology. In general
the dust around S209 has been found to be warmer than that in W3(OH) region. 相似文献
17.
18.
Alpha radiative capture reactions offers the opportunity to study nuclear processes of astrophysical interest. Most of the existing data on these processes have been gained by means of gamma-ray spectroscopy, where the measurements are very difficult due to the low cross sections and the relatively high background in the detectors. We have calculated the two-alpha radiative capture process and excitations of 8Be nuclei interacting using current conservation realistic two- and three-nucleon potentials, at settler energies. We have presented the results of Faddeev-type calculations for current conservation of two- and three-body interactions to cluster nuclear reactions. Our results for cross sections are found to be 128 (140) nanobarn for the current conservation two-body (two-body and three-body) interactions, at the resonance energy with an 14 % (6 %) accuracy in comparison with the recent experimental data, respectively. The results for B (E2) value of 8Be is also found to be 21.7 (20.8) e 2 fm 4, in comparison with the very recent experimental data with an error of 7 % (2 %). Our calculation show that the bulk energies are corrected by improved few-body potentials. 相似文献
19.
The cooling of plasmas in closed coronal loops by thermal conduction is important when considering their detectability at
X-ray and EUV wavelengths. A non-local formalism of thermal conduction originating in laboratory plasmas is used and it is
shown that while the effect is unlikely to be important for loops that are in a steady state, it does play a significant role
in loops that are impulsively heated (e.g., by nanoflares). Such loops are “under-dense”, and so hot electrons have a relatively long mean free path. Analytic and numerical
models are presented, and it is shown that conduction cooling times are lengthened quite considerably. A comparison of various
cooling times with ionisation times is also presented, and it is noted that this conductive physics may enhance the chances
of observing hot nanoflare-heated plasma. 相似文献
20.
The results of the photoelectric photometry with the narrowband CN, C3, C2 and Blue Continuum (BC) IHW interference filters are presented. Observations were carried out with a set of diaphragms of different effective radii. On the base of the Haser model the production rates of the radicals have been obtained. The CN and C2 molecules scale lengths (3.4 × 105 km and 8.5 × 104 km respectively for 1.0 AU heliocentric distance) have been also derived. The dust continuum spectrum is negligibly low in comparison with the molecular one, which stay in agreement with the results of other observations of comet Okazaki-Levy-Rudenko. 相似文献