Search NASA⌕ Search

SEARCH · Search NASA

Results for “Eclipse”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS2010

Implications of the Secondary Eclipse of Exoplanet HAT-P-11b

We observed exoplanet HAT-P-11b and have successfully detected its secondary eclipse. We conducted observations using the Spitzer Space Telescope in the post-cryo mission at 3.6 microns for a period of 22 hours centered on the anticipated secondary eclipse time, to detect the eclipse and determine its phase. Having detected the secondary eclipse, we are at present making a more focused series of observations in both the 3.6 and 4.5 micron bands to fully characterize it. HAT-P-11b is one of only two known exo-Neptunes and has a period of 4.8878 days, radius of 0.422 RJ, mass of 0.081 MJ and semi-major axis 0.053 AU. Measurements of the secondary eclipse will serve to clarify two key issues; 1) the planetary brightness temperature and the nature of its atmosphere, and 2) the eccentricity of its orbit, with implications for its dynamical evolution. We discuss implications of these observations.

Barry, Richard K.↗
NASA NTRS2010

Ionospheric Response to the Total Solar Eclipse of 22 July 2009 as Deduced from VLBI and GPS Data

A total solar eclipse occurred over China at latitudes of about 30 N on the morning of 22 July 2009, providing a unique opportunity to investigate the influence of the sun on the earth's upper ionosphere. GPS observations from Shanghai GPS Local Network and VLBI observations from stations Shanghai, Urumqi, and Kashima were used to observe the response of TEC to the total solar eclipse. From the GPS data reduction, the sudden decrease of TEC at the time of the eclipse, amounting to 2.8 TECU, and gradual increase of TEC after the eclipse were found by analyzing the diurnal variations. More distinctly, the variations of TEC were studied along individual satellite passes. The delay in reaching the minimum level of TEC with the maximum phase of eclipse was 5-10 min. Besides, we also compared the ionospheric activity derived from different VLBI stations with the GPS results and found a strong correlation between them.

Guo, L.↗
NASA NTRS2015

Spectral Eclipse Timing

We utilize multi-dimensional simulations of varying equatorial jet strength to predict wavelength-dependent variations in the eclipse times of gas-giant planets. A displaced hot spot introduces an asymmetry in the secondary eclipse light curve that manifests itself as a measured offset in the timing of the center of eclipse. A multiwavelength observation of secondary eclipse, one probing the timing of barycentric eclipse at short wavelengths and another probing at longer wavelengths, will reveal the longitudinal displacement of the hot spot and break the degeneracy between this effect and that associated with the asymmetry due to an eccentric orbit. The effect of time offsets was first explored in the IRAC wavebands by Williams et al. Here we improve upon their methodology, extend to a broad range of wavelengths, and demonstrate our technique on a series of multi-dimensional radiative-hydrodynamical simulations of HD 209458b with varying equatorial jet strength and hot-spot displacement. Simulations with the largest hot-spot displacement result in timing offsets of up to 100 s in the infrared. Though we utilize a particular radiative hydrodynamical model to demonstrate this effect, the technique is model independent. This technique should allow a much larger survey of hot-spot displacements with the James Webb Space Telescope than currently accessible with time-intensive phase curves, hopefully shedding light on the physical mechanisms associated with thermal energy advection in irradiated gas giants.

Hydrodynamics↗
NASA NTRS2017

Eclipse 2017: Partnering with NASA MSFC to Inspire Students

NASA's Marshall Space Flight Center (MSFC) is partnering with the U.S. Space and Rocket Center (USSRC), and Austin Peay State University (APSU) to engage citizen scientists, engineers, and students in science investigations during the 2017 American Solar Eclipse. Investigations will support the Citizen Continental America Telescopic Eclipse (CATE), Ham Radio Science Citizen Investigation(HamSCI), and Interactive NASA Space Physics Ionosphere Radio Experiments (INSPIRE). All planned activities will engage Space Campers and local high school students in the application of the scientific method as they seek to explore a wide range of observations during the eclipse. Where planned experiments touch on current scientific questions, the camper/students will be acting as citizen scientists, participating with researchers from APSU and MSFC. Participants will test their expectations and after the eclipse, share their results, experiences, and conclusions to younger Space Campers at the US Space & Rocket Center.

eclipse radio solar↗
NASA NTRS1972

The noneffect of solar eclipses on the atmosphere

The effects of the removal of solar radiation, through solar eclipse, on the structure of the thermosphere are examined. The March 7, 1970 eclipse was explored with pilot probe rockets at times during the 42 minute period corresponding to 40, 80, and 100 percent totality. Measuring results show small temperature disturbances especially below 90 km. At levels above 100 km, temperature changes were very large. Results also show that temperature profiles have a warming trend at the start of the eclipse followed by a continuous cooling as the eclipse progresses.

Theon, J. S.↗
NASA NTRS1972

Response of the neutral particle upper atmosphere to the solar eclipse of 7 March 1970.

Results of soundings with a series of five pitot probes launched in conjunction with the solar eclipse of Mar. 7, 1970. Three soundings were programmed to occur at 40, 80, and 100% obscuration of the sun (at 100 km) during a 42-min period. The remaining two soundings were made 24 hr before and after the eclipse. The five soundings yielded neutral particle pressure, temperature, and density profiles over the altitude regime from 30 to 125 km. Below 95 km, the three density profiles resulting from the eclipse day launches had an average deviation of less than 1.5%. Above 95 km, density changes of up to 20% were observed. Such changes in density are comparable in magnitude to those normally observed over a period of several hours. On Mar. 10, 1971, three additional pitot probes were launched at times identical to those of the 1970 eclipse day. Comparison of the two sets of data should provide for a more objective analysis regarding atmospheric response to solar input.

Horvath, J. J.↗
NASA NTRS1972

Electron loss coefficients for the D-region of the ionosphere from rocket measurements during the eclipses of March 1970 and November 1966.

Observation that recombination-like electron loss coefficients measured during the March 1970 eclipse coincide with those from the November 1966 eclipse and range from 2 x 10 to the minus 7th power cu cm/sec at Z sub zero + 6 km to 0.00005 cu cm/sec at Z sub zero -2 km, where Z sub zero is the altitude of the steep gradient of electron concentration. During totality, Z sub zero was 82.5 km in 1970, and 86.8 km in 1966. For full-sun conditions, Z sub zero was 84 km on both eclipse days. Attachment-like electron loss coefficients from both eclipses are in good agreement below Z sub zero, and have a nearly constant value of about 0.008 per sec. Below Z sub zero, attachment-like loss rates agree with production rates - i.e., electron concentration is proportional to electron production.

Mechtly, E. A.↗
NASA NTRS1972

March 7, 1970 solar eclipse investigation

Studies from rockets directed toward establishing the solar X-ray fluxes during the 7 March 1970 total eclipse over the North American continent are reported. A map of the eclipse path is presented. The measured absorption profiles for the residual X-rays are useful in establishing their contribution to the D and E region ionization during the eclipse. The studies were performed with two Nike-Apache payloads launched over Wallops Island, Virginia. In addition to three X-ray detectors in the 1 to 8A, 8 to 20A and 44 to 60A bands, there was included in the payloads two additional experiments. These were an electric field experiment and an epithermal photoelectron experiment. The X-ray instrumentation, payload description, flight circumstances and finally, the X-ray results obtained are described. The various computer codes employed for the purpose of reducing the telemetered data as well as the eclipse codes are included.

Accardo, C. A.↗
NASA NTRS1973

Feasibility study for the use of a YF-12 aircraft as a scientific instrument platform for observing the 1970 solar eclipse

The scientific and engineering findings are presented of the feasibility study for the use of a YF-12 aircraft as a scientific instrument platform for observing the 1970 solar eclipse. Included in the report is the computer program documentation of the solar eclipse determination; summary data on SR-71A type aircraft capabilities and limitations as an observing platform for solar eclipses; and the recordings of an informal conference on observations of solar eclipses using SR-71A type aircraft.

Mercer, R. D.↗
NASA NTRS1973

Analysis of partial-reflection data from the solar eclipse of 10 Jul. 1972

Partial-reflection data collected for the eclipse of July 10, 1972 as well as for July 9 and 11, 1972, are analyzed to determine eclipse effects on D-region electron densities. The partial-reflection experiment was set up to collect data using an on-line PDP-15 computer and DECtape storage. The electron-density profiles show good agreement with results from other eclipses. The partial-reflection programs were changed after the eclipse data collection to improve the operation of the partial-reflection system. These changes were mainly due to expanded computer hardware and have simplified the operations of the system considerably.

Bean, T. A.↗
NASA NTRS1976

Galilean satellites - Observations of mutual occultations and eclipses in 1973

Seven Galilean satellite mutual events, two occultations and two eclipses of Europa and three eclipses of Io, were observed at three wavelengths (0.35, 0.50, 0.91 micrometers) with a time resolution of 0.1 sec. Preliminary model fits to the light curves are presented. Model satellites with different albedo distributions (uniform disk, bright solar caps, bright quadrant) are used in generating model occultation and eclipse curves to demonstrate the sensitivity of observed light curves to the brightness distribution on the surface of the occulted or eclipsed satellite. At the present the observations yield no conclusive information of the limb-darkening of Io. The best data for Europa indicate that the satellite is limb-darkened at both 0.50 and 0.91 micrometers.

Wasserman, L. H.↗
NASA NTRS1976

Observational and theoretical temperatures for a total lunar eclipse

Temperature profiles from seven regions of the moon were recorded during a total eclipse using an infrared radiometer and telescope. The eclipse was visible from beginning to end. Target areas chosen range from mare areas to mountainous highlands. Theoretical temperature curves were calculated using a thermophysical model in which the lunar material properties are variable. These curves are compared with the experimental data. A description of the instrumentation, observations, calibration, signal reduction, and the theoretical model is given. The results show excellent agreement between the observational and theoretical temperatures during the eclipse. The apparent differences between the observed and calculated temperatures during pre- and post-eclipse are minimal after directional radiation is taken into account.

Fountain, W. F.↗
NASA NTRS1978

Galilean satellites - Analysis of photometric eclipses

The excellent series of photometric eclipses of the Galilean satellites observed at Harvard from 1878 to 1903, which formed the basis for Sampson's study of the Galilean satellites, have been combined with the relatively few available post-1903 photometric eclipse observations in order to evaluate the satellite parameters which occur in the new theory of motion of the satellites. After obtaining values for the epsilon-beta parameters, the mutual eclipses and occultations observed in 1973 are compared with the new theory in order to assess the degradation which might occur in the 84 years which have elapsed since the mean epoch of the photometric eclipses. The results indicate that the new theory satisfactorily can predict ephemeris positions of the Galilean satellites over spans of nearly a century and that it will be a useful tool for analyzing future observations.

Lieske, J. H.↗
NASA NTRS1979

ATS-5 and ATS-6 potentials during eclipse

The ATS 5 and ATS 6 data for spacecraft charging during eclipse conditions is analyzed. The ATS 5 and ATS 6 charged to voltages greater than 100 volts for about 55 percent of the eclipse periods examined. The mean spacecraft potential during eclipse was 2 keV for ATS 5, and the highest potential measured was 10 kilovolts. For ATS 6, the mean potential during eclipse was 4 keV, the highest potential measured 20 keV. The average measured spacecraft potentials for both ATS 5 and 6 depend approximately linearly upon Kp. This relationship is due mainly to the dependence of electron current density on Kp near midnight. Spacecraft potentials at geosynchronous orbit may, to a rough approximation, thus be inferred from ground-based measurements of Kp, the planetary 3-hour index.

Rubin, A. G.↗
NASA NTRS1978

Comparison of ozone concentrations obtained from Skylab eclipse and ozonesonde measurements

The satellite eclipse technique of ozone measurement is evaluated to determine its accuracy and resolution. The method of obtaining ozone concentrations from ground-based observations of eclipsing satellites is described, the theory of this method is outlined, and the data reduction procedure is summarized. It is shown that the satellite eclipse technique successfully measures the vertical distribution of ozone from 15 to 40 km with precisions ranging from + or - 12% between 20 and 35 km and + or - 25% at both 15 and 40 km. The ozone profile is found to be in good agreement with in situ measurements obtained from an ozonesonde launched near the eclipse tangent point at local sunset, the percent differences being less than 14% from 20 to 40 km.

Mcdougal, D. S.↗
NASA NTRS1980

Measurements of NO, O3, and temperature at 19.8 km during the total solar eclipse of 26 February 1979

Local measurements of stratospheric NO and O3 mixing ratios and air temperature were made during the total solar eclipse of 26 February 1979. The instrumentation was carried aboard a U-2 aircraft flown at an altitude of 19.8 km in the region near 47 deg N, 112 deg W. Eclipse maximum occurred approximately in the middle of the 2-3/4-hr measurement period. The NO mixing ratio was reduced at least a factor of 25 at the maximum of the eclipse. The decrease and recovery of NO during the passage of the Moon's shadow over the measurement region follows approximately the predictions of two independent models. No change was observed in either the O3 mixing ratio or the air temperature that could be attributed to the eclipse.

Starr, W. L.↗
NASA NTRS1982

An ultraviolet investigation of the unusual eclipsing binary system FF AQR

A series of seven low dispersion IUE exposures in ultraviolet and wavelength regions obtained on December 6, 1981 during the eclipse of the subdwarf, during egress, and out of eclipse is analyzed. These observations and the binary phase at which they were made are shown on a schematic representation of the V-band light curve obtained in 1975. The depth in V is 0.15 mag. The circles are IUE V magnitudes from FES measures obtained during the observing run. They indicate an eclipse depth some 0.05 mag lower than expected, possibly due to difficulties with the color term in the FES calibration. The eclipse depths of Dworetsky in U, B and V were assumed in the calculations.

Dorren, J. D.↗
NASA NTRS1983

MM Herculis - An eclipsing binary of the RS CVn

V, B and U differential photoelectric photometry has been obtained for the RS Canum Venaticorum-class eclipsing binary star MM Her, with the light outside the eclipse being Fourier-analyzed to study wave migration and amplitude. These, together with the mean light level of the system, have been monitored from 1976 through 1980. Observations within the eclipse have revealed eclipses to be partial, rather than total as previously thought. The geometric elements of the presently rectified light curve are forced on the pre-1980 light curves and found to be compatible. With these elements, and previously obtained double line radial velocity curves, new absolute dimensions of 1.18 solar masses and 1.58 solar radii are calculated for the hotter star and 1.27 solar masses and 2.83 solar radii for the cooler star. The plotting of color indices on the color-color curve indicates G2V and K2IV spectral types.

Sowell, J. R.↗