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1.
Height profiles of auroral emissions at 3914 Å, 4861 Å, and 5577 Å were obtained in two rocket flights through medium intensity stable aurora. The 3914 Å N2+ integral intensity data were compared with intensity variations predicted by an auroral model for a range of primary electron energy spectra. The observed profiles for the two flights were well reproduced respectively by a 5.6 keV mono-energtic flux and by a flux with an exponential spectrum cutting off around 12 to 15 keV. The data for 5577 Å (available only above 120 km) bear a constant ratio to that for 3914 Å. The emission profiles derived for 3914 Å, peak at 115 and 107 km respectively.  相似文献   

2.
The July 12, 1973, occultation of Europa by Io was observed in 30 wavelength channels in the spectral region λλ3200-11, 000 Å with the 200-inch Hale telescope and a multichannel spectrometer. The data are presented in absolute units above the Earth's atmosphere. The data are analyzed to obtain the spectral reflectivity of seven localized areas on the disk of Europa centered on 324°W longitude. The equatorial material is confirmed to be darker than the eastward-skewed bright north polar cap and a hint is evident that the darker material as well may be somewhat redder than the cap material.  相似文献   

3.
During the evening of 9 April and the morning of 10 April 1969, the twilight zenith intensity of the atomic oxygen red line OI(3P-1D) at 6300 Å was measured at the Blue Hill Observatory (42°N, 17°W). At the same time incoherent scatter radar data were being obtained at the Millstone Hill radar site 50 km distant. We have used a diurnal model of the mid-latitude F-region to calculate the ionospheric structure over Millstone Hill conditions similar to 9–10 April 1969. The measured electron temperature, ion temperature, and electron density at 800 km are used as boundary conditions for the model calculations. The diurnal variation of neutral composition and temperature were obtained from the OGO-6 empirical model and the neutral winds were derived from a semiempirical three-dimensional dynamic model of the neutral thermosphere. The solar EUV flux was adjusted to yield reasonable agreement between the calculated and observed ionospheric properties.This paper presents the results of these model computations and calculations of the red line intensity. The 6300 Å emission includes contributions from photoelectron excitation, dissociative recombination, Schumann-Runge photodissociation and thermal electron impact. The variations of these four components for morning and evening twilight between 90–120° solar zenith angles, and their relative contributions to the total 6300 Å emission line intensity, are presented and the total is compared to the observations. For this particular day the Schumann-Runge photodissociation component, calculated using the solar fluxes tabulated by Ackermann (1970), is the dominant component of the morning twilight 6300 Å emission. During evening twilight it is necessary to utilize a lower O2 density than for the morning twilight in order to bring the calculated and observed 6300 Å emission rates into agreement. The implication that there may be a diurnal variation in the O2 density at the base of the thermosphere is discussed in the light of available experimental data and current theoretical ideas.  相似文献   

4.
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.  相似文献   

5.
The absolute intensities and the centre-to-limb variations of the Sun at three wavelengths of 1629 Å, 1684 Å, and 1739 Å were measured by a rocket-borne spectrometer flown from the Kagoshima Space Centre on 1 September 1971. The spectrometer was a double-dispersive trichrometer, whose spectral and spatial resolutions were 8.3 Å and 1.3 respectively. The results concerning the absolute intensities were similar to those measured by the Harvard College Observatory group. The results for the centre-to-limb variation at 1629 Å and 1684 Å seem to support the HSRA model but not those at 1739 Å.  相似文献   

6.
We have obtained spectroscopic observations in coronal emission lines by choosing two lines simultaneously, one [Fe x] 6374 Å and the other [Fe xi] 7892 Å or [Fe xiii] 10747 Å or [Fe xiv] 5303 Å. We found that in 95 per cent of the coronal loops observed in 6374 Å, the FWHM of the emission line increases with height above the limb irrespective of the size, shape and orientation of the loop and that in case of 5303 Å line decreases with height in about 89 per cent of the coronal loops. The FWHM of 7892 Å and 10747 Å emission lines show intermediate behavior. The increase in the FWHM of 6374 Å line with height is the steepest among these four lines. We have also studied the intensity ratio and ratio of FWHM of these lines with respect to those of 6374 Å as a function height above the limb. We found that the intensity ratio of 7892 Å and 10747 Å lines with respect to 6374 Å line increases with height and that of 5303 Å to 6374 Å decreases with height above the limb. This implies that temperature in coronal loops will appear to increase with height in the intensity ratio plots of 7892 Å and 6374 Å; and 10747 Å and 6374 Å whereas it will appear to decrease with height in intensity ratio of 5303 Å to 6374 Å lineversus height plot. These findings are up to a height of about 200 arcsec above the limb. The varying ratios with height indicate that relatively hotter and colder plasma in coronal loops interact with each other. Therefore, the observed increase in FWHM with height above the limb of coronal emission lines associated with plasma at about 1 MK may not be due to increase in non-thermal motions caused by coronal waves but due to interaction with the relatively hotter plasma. These findings also do not support the existing coronal loop models, which predict an increase in temperature of the loop with height above the limb.  相似文献   

7.
Absolute photoelectric intensity measurements of 104 selected lunar regions are given in five interference filters 4035 Å, 4765 Å, 5538 Å, 6692 Å and 7922 Å. Among these regions, eighteen lunar regions have been measured repeatedly for several phase angles between +86° and ?43°. They include observations made very close to the full Moon. A catalogue has been compiled to serve as a basin for possible investigations of colour contrasts of lunar grounds, variation of the ratio of reflectivity with wavelengths and phase angles for morphological studies. The study can be extended for the brightness phase variation, opposition effect and radiance factors at zero phase in five colours.  相似文献   

8.
New narrow-band (100 Å) photoelectric area-scanning photometry of the Uranus disk is reported. Observations were concentrated on the two strong CH4 bands at λ 6190 and 7300 Å. Adjacent continuum regions at λ 6400 and 7500 Å were also measured for comparison. Both slit and pinhole scans were made in orthogonal directions. Disk structure in each waveband is apparent through lack of circular symmetry in the intensity distribution over the Uranus image. Polar brightening is especially prominent in the λ 7500-Å waveband. Coarse quantitative determinations of the true intensity distribution over the Uranus disk were made. For the λ 6190-Å CH4 band, Uranus exhibits a disk of essentially uniform intensity except for a hint of polar brightening. For the λ 7300-Å CH4 band, moderate limb brightening is apparent. Specifically, the true intensities at the center and limb of the planetary disk are approximately in the proportion 1:2. Extreme limb brightening, with a corresponding intensity ratio greater than 1:4, is not permitted by the observational data.  相似文献   

9.
Photometers on the ISIS-II spacecraft provide a view of the atomic oxygen 5577 and 6300 Å emissions and the N2+ 3914 A? emission detected as dayside aurora in the magnetospheric cleft region. The 6300 Å emission forms a continuous and permanent band across the noon sector, at about 78° invariant latitude, with a defined region of maximum intensity that is never less than 2kR (uncorrected for albedo), and is centred near magnetic noon. There are significant differences in the intensity patterns on either side of noon and their responses to geomagnetic activity. Discrete 3914 Å auroral forms appear within this region, at preferred locations that cannot be precisely specified, but which tend to the poleward edge of the 6300 Å emission in the evening, and the equatorward edge in the morning where the difference between the two emissions is greatest. It is concluded that the discrete auroras observed by all-sky cameras in the day sector do follow the 6300 Å emission through the cleft region, though a definite cleft boundary is not defined. Substantial 6300 Å emission having a peak intensity near noon is also seen in the low latitude “outer auroral belt”, while the diffuse 3914 Å emission tends to show a relative minimum near noon. On the morning side the 3914 Å intensity is displaced to lower latitude and earlier local times, compared to the 6300 Å emission.  相似文献   

10.
The flash spectra of the solar chromosphere and corona were measured with a slitless spectrograph before, after, and during the totality of the solar eclipse of 11 July 2010, at Easter Island, Chile. This eclipse took place at the beginning of Solar Cycle 24, after an extended minimum of solar activity. The spectra taken during the eclipse show a different intensity ratio of the red and green coronal lines compared with those taken during the total solar eclipse of 1 August 2008, which took place toward the end of Solar Cycle 23. The characteristic coronal emission line of forbidden Fe xiv (5303 Å) was observed on the east and west solar limbs in four areas relatively symmetrically located with respect to the solar rotation axis. Subtraction of the continuum flash-spectrum background led to the identification of several extremely weak emission lines, including forbidden Ca xv (5694 Å), which is normally detected only in regions of very high excitation, e.g., during flares or above large sunspots. The height of the chromosphere was measured spectrophotometrically, using spectral lines from light elements and compared with the equivalent height of the lower chromosphere measured using spectral lines from heavy elements.  相似文献   

11.
The intensity of Jupiter's He 584 Å airglow has been measured by the Voyager U.V. spectrometers. The disc-averaged brightness is about 4 Rs and limb darkening is present. The intensity probably varies with longitude, the variation being out of phase with the H Lyman-α intensity bulge. Modelling of resonance scattering of the solar He 584 Å line by Jupiter's atmosphere has shown that the hydrogen and helium emissions can be explained about equally well by at least two self-consistent scenarios involving the structure (temperature and eddy diffusion coefficient) and excitation of the atmosphere. All our evidence points to a dramatic change of conditions in the Jovian atmosphere in the time between Pioneer and Voyager encounters.  相似文献   

12.
We present the results of our photometric and spectroscopic observations of the symbiotic nova HM Sge in 1994–2002. After its outburst in 1975, the star was shown to fade in the U, B, V bands at a rate of about \(0\mathop m\limits_. 05\) per year. The behavior of the B-V and U-B color indices reflects the variations of emission lines and, in part, the fading of the erupted component. We have studied the evolution of the emission spectrum in the range from Hδ to λ7751 Å over the period 1986–2002. The absolute fluxes in the hydrogen lines decreased by half, the ionization of the gaseous envelope continued to increase, and the Raman O VI lines appeared and strengthened. The significant (threefold) decrease in the ratio of the auroral and nebular O III lines is interpreted as a drop in the electron temperature of the envelope as its density decreased by a factor of about 1.5. We have measured the absolute intensity of the near-infrared continuum up to 10 000 Å and show that the infrared continuum follows the pulsations of the Mira star in the system HM Sge. We conclude that the dust envelope around the cool component became noticeably transparent in the 1990s.  相似文献   

13.
The ultraviolet flux from the entire lunar disk has been measured in a series of rocket flights from Woomera at several wavelength bands in the range 2400-2900 Å and also at the wavelength of the hydrogen Lα line (1216 Å). Comparison of these measurements with other observations shows that between the visible and middle ultraviolet part of the spectrum, the lunar albedo decreases sharply towards shorter wavelengths falling to (0.7 ± 0.1) percent at 2400 Å which is a factor of ten less than the visible albedo. The measured albedo at 1216 Å is (0.3 ± 0.1) percent indicating that the decline in reflectivity with decreasing wavelength is less rapid at far ultraviolet wavelengths than is the decline between visible and middle ultraviolet.  相似文献   

14.
We conducted an experiment in conjunction with the total solar eclipse of 29 March 2006 in Libya that measured the coronal intensity through two filters centered at 3850 Å and 4100 Å with bandwidths of ≈?40 Å. The purpose of these measurements was to obtain the intensity ratio through these two filters to determine the electron temperature. The instrument, Imaging Spectrograph of Coronal Electrons (ISCORE), consisted of an eight inch, f/10 Schmidt Cassegrain telescope with a thermoelectrically-cooled CCD camera at the focal plane. Results show electron temperatures of 105 K close to the limb to 3×106 K at 1.3R ⊙. We describe this novel technique, and we compare our results to other relevant measurements. This technique could be easily implemented on a space-based platform using a coronagraph to produce global maps of the electron temperature of the solar corona.  相似文献   

15.
Modeling of the dayglow spectrum in the wavelength region between 3300 and 3500 Å indicates that the N2 second positive (0,0) band at 3371 Å is blended with the Vegard-Kaplan (0,9) band. A recent analysis of rocket observations of the dayglow shows that 20–30% of a 3371 Å narrow band filter-photometer signal is due to the VK emission (Conway and Christensen, 1983). Kopp et al. (1977) and Hernandez et al. (1983) reported analyses of 3371 Å photometer observations from the Visible Airglow Experiment on the Atmospheric Explorer-C (AE-C) satellite which did not consider the Vegard-Kaplan (VK) emission. The observations were compared to theoretical estimates of the second positive volume emission rate based on a photoelectron model and on absolute fluxes measured by the Photoelectron Spectrometer experiments on AE-C and AE-E. Inclusion of the VK band in the AE analysis would bring the reported photoelectron theory into agreement with the airglow observations. However, the overestimate of the N2 second positive airglow predicted by the AE-E photoelectron flux measurements increases to a factor of nearly two rather than the 20–30% reported by Hernandez et al. (1983).  相似文献   

16.
The paper presents the variation of 5577 Å line intensity with relative sunspot number, and 10.7 cm solar flux. The study has obtained the following important results.[(i)] The 5577 Å line intensity at Calcutta is plotted against relative sunspot number, and the variable component of 10.7 cm solar flux during 1984–1985, which is the secondary peak of the descending phase of the 21st solar cycle. The intensity curves show periodic variation with different solar parameters.[(ii)] The 5577 Å line intensity at Mt. Abu also shows periodic variation with solar parameters during the period 1965–1968 when there was a peak phase of the 20th solar cycle.[(iii)] A possible explanation for such variation is also presented.  相似文献   

17.
Ultraviolet spectrometer measurements of the reflectance at 3050 Å are modeled to give pressure-altitudes for Mars assuming a quiescent atmosphere. Ultraviolet light that is Rayleigh-scattered by the Mars molecular atmosphere, with allowance for uniform turbidity, is proportional to surface pressure independent of atmospheric temperature structure. All model constants except the over-all scaling factors are found by requiring ultraviolet spectrometer pressures of 47 locations on the planet to be the same when measured at different geometries. The overall scaling factor is found by intercomparison with Mariner 9 occultation pressures. Comparison with other Mars pressure-altitude measurements show deviations from the assumption of uniform turbidity to occur over the Hesperia plateau for ultraviolet measurements obtained during the 13–26 February 1972 time period.  相似文献   

18.
Observations with a new near infrared imaging spectrometer with ～15 Å resolution are presented. Twelve spectral images of Saturn in the vicinity of the 8900 Å CH4 absorption complex were obtained and their interpretation discussed. Spectral images of Jupiter were also obtained and several of these at widely separated wavelengths were subjected to a Minnaert analysis.  相似文献   

19.
The measured and calculated intensities of the 6300 Å emission are compared on the basis of the measured Doppler temperature and intensity of the red emission during night and twilight and the F2 layer parameters. There is satisfactory correlation between them for the quiet geomagnetic periods (Kp? 2).  相似文献   

20.
We present spatially resolved measurements of Saturn's absolute reflectivity in methane bands at 6190, 7250, and 8900 Å and in nearby continuum regions. Images were obtained through narrow-band interference filters with a 500 × 500-pixel charge-coupled device. Band/continuum ratios were measured to high accuracy by referencing to the ring brightness in each image. Several data processing techniques enhanced the quality of the observations. These are the use of the ring symmetry to find center position and orientation, accurate subtraction of ring light, and constrained image deconvolution. Uncertainty in the continuum absolute reflectivity is ±10%. Uncertainties in band/continuum ratios are from one to several percent. The Equatorial Zone was much brighter than any other latitude in the strong 8900 band image. Northern mid-latitudes were brighter than southern mid-latitudes. The latter observation indicates fewer high-altitude aerosols in the south, a possible result of atmospheric dynamics or seasonal sublimation of NH3 crystals. The data are tabulated and presented in a form suitable for quantitative scattering model analyses.  相似文献   

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