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Atmospheric sodium at the Moon was observed for altitudes from the ground up to 1800 km from 18 April to 13 May 1998, a period including an entire lunar month. Because of bad weather, coverage was incomplete but we present the analysis of 36 spectra largely from near first and third quarter phases and passage through full moon. The apparatus used was the specially built clear aperture 16.5 cm, 203 cm focal length, Mt. Lemmon Lunar Coronagraph on Mt. Lemmon in the Catalina Mountains of Tucson, Arizona. Data are interpreted in terms of Chamberlain fits to the observed emission rate using both one equivalent temperature and two source components (with both cold and hot density distributions). The extent and equivalent temperatures of the exosphere during this period trended towards an extended coma with very little fraction in the thermally accommodated regime, even near the surface. Preliminary data-model comparisons suggest that these measurements are consistent with rates and spatial distributions expected from a photonstimulated desorption source, although evidence for one, or possibly two, periods of notable meteoroid impact source might be present. A compilation of new and previously published observations illustrates an increased emission by sodium at third quarter over that of first quarter, a result that suggests that the dayside exospheric content increases, at least occasionally, following transit of the Moon through the Earth's magnetosphere. PACS Nos.: 92.60hw, 92.60Vb, 94.80+g, 95.30Dr, 95.75Fg, 95.85Kr Pendant un mois lunaire complet, entre le 18 avril et le 13 mai 1998, nous avons mesure le sodium dans l'atmosphere de la Lune, du sol jusqu'a 1800 km d'altitude. A cause de la mauvaise temperature, la couverture est incomplete, mais nous presentons l'analyse de 36 spectres surtout pres du premier et du troisieme quartier, avec des passages sur la pleine lune. L'appareil utilise etait le Coronographe Lunaire du mont Lemmon dans les montagnes Catalina pres de Tucson en Arizona. Cet appareil dedie a une pleine ouverture de 16,5 cm et une longueur focale de 203 cm. Les donnees sont interpretees par ajustement numerique de Chamberlain aux taux d'emission observes, utilisant a la fois une temperature equivalente et deux sources (avec des distributions de densite froides et chaudes). L'etendu et la temperature equivalente de l'exosphere pendant cette periode indiquaient un coma etendu avec une toute petite fraction en regime thermique, m&ne pres de la surface. Les comparaisons preliminaires entre donnees et modele suggerent que ces mesures sont coherentes avec les taux et les distributions spatiales attendus d'une source de desorption stimulee par photons, quoique il y a des indications d'une ou m&ne deux periodes de sources significatives par impact de meteorites. Une compilation de nouvelles donnees avec des resultats deja publiees illustre une augmentation de l'augmentation du sodium pendant le troisieme quartier, compare au premier quartier, ce qui suggere que le contenu de l'exosphere de jour augmente, au moins occasionnellement, apres le transit de la Lune a travers la magnetosphere de la Terre. [Traduit par la Redaction], 1. Introduction In 1998 we sought to provide more lunar atmospheric sodium measurements to better identify the relative importance of what were then considered sources of the exosphere. The observations [...]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2006.05.021 Byline: A.L. Sprague (a), D.M. Hunten (a), L.R. Doose (a), R.E. Hill (a), W.V. Boynton (a), M.D. Smith (b), J.C. Pearl (b) Keywords: Mars; atmosphere; Abundances; atmospheres; Spectroscopy Abstract: Our ground-based measurements of martian atmospheric water vapor, made throughout L.sub.s=34[degrees] to 249[degrees], 24 September 1998 to 23 November 1999, during Mars year 24 (MY 24), show changes in Mars' humidity on hourly, daily, and seasonal timescales. We made concomitant measurement of nearby CO.sub.2 bands, and when possible, results were corrected for aerosol extinction using aerosol optical depths derived from our own CO.sub.2 analysis. Where there is spatial and temporal overlap, similar results are obtained for water vapor abundances and aerosol opacities as those observed from the Thermal Emission Spectrometer on Mars Global Surveyor. In addition some further discussion of our published earlier water vapor measurements (1991-1995) is included. Six results from this data set are: (1) the measured aerosol opacity in Mars atmosphere was variable but not greater than I=1, with almost no clear atmosphere being observed, (2) measurements made with the slit crossing many hours of local time on Mars' Earth-facing disk show a diurnal pattern with highest abundances at mid-day and low abundance in very early morning and late afternoon for some but not all measurements, (3) water vapor abundance is patchy on hourly and daily time scales but follows the usual seasonal trends seen by instrumentation on the Mars Atmospheric Water Detector on the Viking Orbiters and by the Thermal Emission Spectrometer on Mars Global Surveyor, (4) there is a slight longitudinal correlation with the ground-ice observed by the Gamma Ray Spectrometer on Mars Odyssey, (5) there is evidence of the Low Southern Latitude Summer Minimum in our water vapor measurements but our data set for southern summer is limited, and (6) MY 24 appears to be wetter than MY 22 and MY 23. Author Affiliation: (a) Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721, USA (b) Goddard Space Flight Center, Baltimore, MD 20771, USA Article History: Received 4 November 2005; Revised 21 March 2006

The gamma ray spectrometer on the Mars Odyssey spacecraft measured an enhancement of atmospheric argon over southern high latitudes during autumn followed by dissipation during winter and spring. Argon does not freeze at temperatures normal for southern winter (~145 kelvin) and is left in the atmosphere, enriched relative to carbon dioxide (C[O.sub.2]), as the southern seasonal cap of C[O.sub.2] frost accumulates. Calculations of seasonal transport of argon into and out of southern high latitudes point to meridional (north-south) mixing throughout southern winter and spring., Between autumn (areocentric longitude of the Sun [L.sub.s] 0° to 90°) (1) and winter in the southern hemisphere of Mars, about 25% of the atmosphere accumulates as a thick southern [...]

Measurements of martian atmospheric water vapor made throughout [L.sub.s] = 18.0[degrees]-146.4[degrees] (October 3, 1996-July 12, 1997) show changes in Mars humidity on hourly, daily, and seasonal time scales. Because our observing program during the 1996-1997 Mars apparition did not include concomitant measurement of nearby C[O.sub.2] bands, high northern latitude data were corrected for dust and aerosol extinction assuming an optical depth of 0.8, consistent with ground-based and HST imaging of northern dust storms. All other measurements with airmass greater than 3.5 were corrected using a total optical depth of 0.5. Three dominant results from this data set are as follows: (1) pre-and post-opposition measurements made with the slit crossing many hours of local time on Mars' Earth-facing disk show a distinct diurnal pattern with highest abundances around and slightly after noon with low abundances in the late afternoon, (2) measurements of water vapor over the Mars Pathfinder landing site (Carl Sagan Memorial Station) on July 12, 1997, round 21 ppt [mu]m in the spatial sector centered near 19[degrees] latitude, 36[degrees] longitude while abundances around the site varied from as low as 6 to as high as 28 ppt [mu]m, and (3) water vapor abundance is patchy on hourly and daily time scales but follows the usual seasonal trends. Keywords: Mars Atmosphere; Mars Water Vapor; Remote Sensing of Mars; Mars Pathfinder Site

We present column abundances of water vapor in Mars' atmosphere over high north latitudes for [L.sub.s] 46 [degrees]-146 [degrees] during 1996-1997 and [L.sub.s] 34 [degrees]-180 [degrees] during 1998-1999. These abundances have been obtained by ground-based high-resolving-power spectroscopy in the very near IR (8174-8200 [Angstrom]) from the 1.5-m Catalina observatory near Tucson, AZ. All of the measurements have been corrected for atmospheric dust opacity, which increases the measured water vapor abundance over the 'apparent measurement' by appreciable amounts at long path lengths. Dust measurements in 1998-1999 were made by near simultaneous measurements, with the same instrument, of the C[O.sub.2] absorption lines in the nearby spectral region between 8689 and 8692 [Angstrom]. We use a doubling and adding radiative transfer code to obtain the dust optical thickness. High northern latitude dust opacities were between 0.8 and 1.0 in this data set for 1998-1999. For the high-latitude measurements made in 1996-1997 during and following observed spring dust storm activity, the dust opacity ([[tau].sub.dust] = 0.8) was adopted. The computations account for the geometry of the observations (incoming airmass, outgoing airmass, and phase angle). Measurements show a strong increase in water vapor abundance from 8 to 76 ppt. [micro]m with onset of spring and early summer ([L.sub.s] 34 [degrees]-118 [degrees]) followed by an abrupt drop to less than 1 ppt. [micro]m by summer's end. Key Words: Mars water vapor; water on Mars; Mars atmosphere; Mars' polar regions.

Observations of lunar sodium were made on November 16-18, 1997, at Asiago and Mount Lemmon Observatories. A small enhancement was observed, and we suggest that it was related to the Leonid shower. Visual observations by members of the Association of Lunar and Planetary Observers and the North American Meteor Network show a peak, a few hours wide, at about 12:50 UT on the 17th. The possible enhancement of the lunar Na appears to last at least 3 days, and must be associated with a considerably more extended cloud of particles than that responsible for the bright visual meteors. The circumstances of the 1997, 1998, and 1999 events are discussed. Large showers may occur in 1998 and 1999; the 1998 shower occurs too close to new moon for good atmospheric observations, but if the extended, faint shower is also enhanced the corresponding lunar Na should be observable for a considerably longer period. Key Words: Moon; atmospheres, structure; meteors.

We report results of a part of an organized effort of five observing groups to simultaneously observe sodium in the lunar atmosphere. International Lunar Atmosphere Week spanned the week of September 15-22, 1995. Of the seven nights, we experienced four nights with good viewing conditions. We used the Mt. Lemmon Lunar Coronagraph (MLLC) and DARRK spectrograph. Both are especially designed for lunar atmospheric measurements from the surface extending to an altitude of approximately 1 lunar radius or [approximately]1700 km (860 km geopotential height). Emission rates for Na were compatible with those previously reported for relatively large phase angles (96 [degrees] to 129 [degrees]) with the average total of D2 and D1 emission rate [approximately]6.9 kRayleigh. A thermal component was observed only on the night of September 17, when the solar zenith angle at the limb was only 6 [degrees]. We observed a factor of [approximately]2 greater column abundances over the north pole than over the sunlit equatorial limb on September 18 while on September 19, the equatorial bright limb column abundance was a factor of [approximately]5 higher than the north polar. Apparent geopotential scale heights varied from 279 to 435 km, indicating an extended atmosphere. If the scale heights are represented by a temperature, values are 985 to 1470 K. The data set appears to support the idea that the dominant source during this period was meteoritic impact volatilization. Key Words: lunar atmosphere; sodium atmosphere; meteoritic impact; exospheres.

We analyze an extensive data set of immersion and emersion lightcurves of theoccultation of 28 Sgr by Saturn's atmosphere on 3 July 1989. The data give profilesof number density as a function of altitude at a variety of latitudes, at pressuresranging from about 0.5 to about 20 [micro]bar. The atmosphere is essentiallyisothermal in this range, with a temperature close to 140 K for an assumed meanmolecular weight of 2.135. Owing to favorable ring geometry, an accurate radialscale is available of all observations, and we confirm the substantial equatorialbulge produced by zonal winds of [approximately]450 m/s first observed in theVoyager radio-occultation experiments. The fact that the bulge is still presentat microbar pressures suggests that the equatorial winds persist to high altitudes.According to our radial scale, the 2.4-[micro]bar level, which corresponds tohalf-flux in the stellar occultations, is at an equatorial radius of 60,960 km.This radial scale is in good agreement with the Voyager radio-occultation data atmbar pressures and allows smooth interpolation of the isothermal structure betweenthe stellar-occultation and radiooccultation regions. We do not have such a smoothinterpolation between our data and Voyager ultraviolet occultation data, unlesswe discard the lowest 200 km of Voyager ultraviolet data. When this is done, weobtain a complete atmospheric model from an equatorial radius of 61,500 km down to an equatorial radius of 60,500 km. This model gives excellent agreement betweenall 28 Sgr, Voyager, and Pioneer 11 data. Key Words: occultations; Saturn, atmosphere; Saturn.

We report spectroscopic measurements of sodium in Mercury's atmosphere for the period July 1985-May 1988. Na abundance varies from < 1 x [10.sup.10] atoms [cm.sup.-2] in equatorial regions in March 1987 to as much as ~1.5 x [10.sup.12] atoms [cm.sup.-2] in May 1988. All observations were made using a high-resolution echelle spectrograph on the 61-in. telescope on Mt. Bigelow, Arizona. Strong high-latitude enhancements are common, with the added characteristic that there is usually more at one hemisphere than the other. There is an obvious diurnal correlation, with morning abundances significantly higher than afternoon. We see notable Na emission enhancements when our spectrograph slit is placed over the radar-bright spots at 340 [degrees] mercurian longitude and 55 [degrees] N and 25 [degrees] S latitude. We do not see any trend in column abundance with increasing radiation acceleration. We do not see a significant correlation of abundance with either solar F10.7 flux or sunspot number. Other larger variations occur and must be caused by other factors.

High-resolution spectra of Mercury show no evidence of emission at the wavelength of the lithium resonance doublet, 6708 [Angstrom]. Observations were made with the 1.5-m telescope at the Catalina Observatory, near Tucson, Arizona, with the LPL echelle spectrograph and cooled CCD camera system. With an rms noise level of [approximately]0.1% we set an upper limit for the Li vertical column abundance

Measurements of [H.sub.2]O in the impact plumes of the R and W fragments of Comet SL-9 were made from the Kuiper Airborne Observatory. Water emissions peaked [approximately]12 min after the impacts, and indicate a temperature [approximately]1000 K based upon the relative radiances of two [H.sub.2]O emission features at 6.62 and 6.45 [[micro]meter]. Our analysis shows that the water was probably delivered by Comet SL-9 and is not of jovian origin, and that the C/O ratio in the plume was less than unity. Our calculations, which allow for entrainment of jovian air and use a Halley-like composition for the impactor, show that the R fragment contained ice equivalent to a sphere 90 m in diameter. On the further assumption that we only saw 10% of the material, the diameter of the fragment would be 250 m.

A two-dimensional diabatic model of water transport is used to evaluate measurements of water-vapor column abundance in the southern hemisphere of Mars between 1988 and 1989. The analysis is carried out to study the mean meridional and carbon dioxide condensation/sublimation circulation as well as sources and sinks of atmospheric water in the planet. The results suggest that the southern midlatitudes serve as the sink for the water that disappeared during the period covered by the data.

The night side of Venus was imaged at 18.8 frames per second using coronagraphic optics and a 153-cm telescope during the spring 1993 apparition in a search for lightning. The images were then reduced such that scattered light from the day side was removed and transient signals were sought. Several potential lightning flashes were detected at a wavelength near 777.4 nm. The six flashes were calculated to have optical energies ranging from [10.sup.8] to 2 X [10.sup.9] J. The detected flashes occur at a rate of 2.7 x [10.sup.-12] [km.sup.-2] [sec.sup.-1]. A single flash detected in control images yields a false rate 0.66 times the non-control rate; however, it now appears that the lightning spectrum contains a line in the wing of the 'control' filter bandpass. We now believe this detection to be a valid lightning flash. A limit of detection is set at 5 X [10.sup.6] J for 95% detection and 1.5 X [10.sup.6] J for 50% detection. With this limit, it would have been possible to observe the brightest of Earth-like lightning should it exist on Venus.

The new inversion model, developed by fitting the Kuiper Airborne Observatory lightcurve to conventional atmosphere models that have a troposphere and an inversion layer near the base of the stratosphere, indicates that the atmosphere of Pluto consists of N2, CO and CH4. Spectral observations of Pluto indicate that CH4 ice present on the surface of Pluto is warmer than N2/CO ices. This indicates the large mixing ratio of CH4 in the atmosphere of Pluto.

Neutral calcium in the atmosphere of mercury was searched by high resolution spectroscopic measurements at 4227 angstroms, with 9.0 KR as the upper limit of the intensity. The relative Ca column abundance was lesser than 7.4 times 10 to the power 8 atoms per square centimeter, with a Ca/Na ratio being lesser than 0.005. The lifetimes of the calcium atoms with the photoionization is 60% of the sodium atoms lifetimes, their cosmic abundances being similar.

Saturn's pole, as defined by the ring plane, can be determined by the geometry of the 3 July 1989 occultation of 28 Sgr by Saturn. High precision timing of 12 circular edges in the C-ring with radius from 84750 to 90615 kilometers, Cassini division's three features, Encke gap's edges and the Keeler gap's outer edges were used to define Saturn's pole by the ring plane. The observations were made from one station in the southern hemisphere, and five stations in the northern hemisphere. This provided a terrestrial chord separation of 10,000 km. The radio and stellar-occultation data of the ring radii obtained from Voyager is used to solve the position angle and opening angle of the apparent ring ellipses.

Absorption spectra obtained by intracavity laser spectroscopy (ILS) often contain fringe patterns that significantly mask absorption features and hamper the quantitative analysis of ILS data. Both the parasitic etalon fringes and the fringes that originate from spatially localized losses can be suppressed by a low-amplitude audio-frequency vibration of a folding mirror in the laser cavity. Using this methodology, we show that ILS spectra recorded with multimode lasers that contain nonideal intracavity surfaces have essentially no fringe contamination. The elimination of fringe contamination improves the detection sensitivity of ILS under normal experimental conditions and thus expands the potential for ILS applications.

Atmospheric sodium and potassium on the Moon are analyzed. The results may be explained by a model of competing release mechanisms in which thermal desorption plays a major role. Atoms may be found at higher altitudes due to thermal desorption which imbibes the atoms with enough energy when they are on the surface of the Moon to attain the heights in which they are found. In cooler regions, there are less atoms within the same altitude. Sodium may be found in a region between 119 to 611 km above the surface and potassium may be found in a region between 85 and 154 km.

On 7 December 1995, the NASA Galileo probe provided in situ measurements of the helium abundance in the atmosphere of Jupiter. A Jamin interferometer measured the refractive index of the jovian atmosphere in the pressure region from 2 to 14 bars. These measurements indicate that the atmospheric helium mole fraction is 0.136 ± 0.004. The corresponding helium mass fraction is slightly below the presolar value, which suggests that separation of helium from hydrogen in Jupiter's interior is only in its early stages., In 1977, when the instruments for the Galileo probe were chosen, it was generally thought that the He abundance in the jovian atmosphere was the same as that which was [...]

ON 8 FEBRUARY 1990 THE EXTREME Ultraviolet Spectrometer (EUV) on the Galileo spacecraft obtained a spectrum of Venus in the wavelength range of 55 to 125 nm. After this encounter, [...]

Ultraviolet Spectrometer Observations of Neptune and Triton BEFORE THE VOYAGER ENCOUNTER, neither Nepture nor Triton had been detected at wavelengths shorter than 1700 [angstroms]. Measurements of the ultraviolet (UV) reflection [...]

A. L. Sprague et al. (1) attribute an enhanced emission in the potassium (K) D lines of 14 October 1987 in the equatorial region of Mercury to a diffusion source [...]

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Discusses measurements from the Galileo space probe, regarding the abundance of helium in Jupiter's atmosphere. Use of a Jamin interferometer, to measure the refractive index of the planet's atmosphere; Indications about the atmospheric helium mole fraction; Comparison of the helium mass fraction to the presolar value; What this mass fraction indicates about the separation of helium from hydrogen in the planet's interior.