249 research outputs found
Total ozone derived from UV spectrophotometer measurements on the NASA CV-990 aircraft for the fall 1976 latitude survey flights
An ultraviolet interference filter spectrophotometer was modified to use a photodiode and was flown on latitude survey flights in the fall of 1976. Comparison with Dobson station total ozone values shows agreement between UVS and Dobson total ozone of + or - 2 percent. The procedure used to convert UVS measured ozone above the aircraft altitude to total ozone above ground level introduces an additional 2 percent deviation for very high altitude UVS ozone data. Under stable aircraft operating conditions, the UVS derived ozone values have a variability, or reproducibility, of better than + or -1 percent. The UVS data from the latitude survey flights yield a detailed latitude profile of total ozone over the Pacific Ocean during November 1976. Significant latitudinal structure in total ozone is found at the middle latitudes (30 deg to 40 deg N and S)
Feasibility study of alpha particle densitometers for measuring planetary atmospheric density Final report, Jul. 1968 - May 1969
Radioactive alpha particle density measuring system for atmospheric analyse
Design, fabrication and calibration of alpha particle densitometers for measuring planetary atmospheric density
An alpha particle densitometer was developed for possible application to measurement of the atmospheric density-altitude profile on Martian entry. The device uses an Am-241 radioactive-foil source, which emits a distributed energy spectrum, located about 25 to 75 cm from a semiconductor detector. System response - defined as the number of alphas per second reaching the detector with energy above a fixed threshold - is given for Ar and CO2. The altitude profile of density measurement accuracy is given for a pure CO2 atmosphere with 5 mb surface pressure. The entire unit, including dc-dc converters, requires less than 350 milliwatts of power from +28 volts, weighs about 0.85 lb and occupies less than 15 cubic inches volume
Flight of a UV spectrophotometer aboard Galileo 2, the NASA Convair 990 aircraft
An ultraviolet interference-filter spectrophotometer (UVS) fabricated for aircraft-borne use on the DOT Climatic Impact Assessment Program (CIAP) has been successfully tested in a series of flights on the NASA Convair 990, Galileo II. UV flux data and the calculated total ozone above the flight path are reported for several of the flights. Good agreement is obtained with the total ozone as deducted by integration of an ozone sonde vertical profile obtained at Wallops Island, Virginia near the time of a CV-990 underpass. Possible advantages of use of the UVS in the NASA Global Atmospheric Sampling Program are discussed
Annual Report. Teilinstitut Kernphysik des Instituts fuer Angewandte Kernphysik. (July 1, 1979 - June 30, 1980)
Galaxy cluster mass bias from projected mass maps: The Three Hundred-NIKA2 LPSZ twin samples
The determination of the mass of galaxy clusters from observations is subject
to systematic uncertainties. Beyond the errors due to instrumental and
observational systematic effects, in this work we investigate the bias
introduced by modelling assumptions. In particular, we consider the
reconstruction of the mass of galaxy clusters from convergence maps employing
spherical mass density models. We make use of The Three Hundred simulations,
selecting clusters in the same redshift and mass range as the NIKA2
Sunyaev-Zel'dovich Large Program sample: and . We study different
modelling and intrinsic uncertainties that should be accounted for when using
the single cluster mass estimates for scaling relations. We confirm that the
orientation of clusters and the radial ranges considered for the fit have an
important impact on the mass bias. The effect of the projection adds
uncertainties to the order of to to the mass estimates. We also
find that the scatter from cluster to cluster in the mass bias when using
spherical mass models is less than of the true mass of the clusters
Type 2 Structure-Preserving Signature Schemes Revisited
Abstract. Abe, Groth, Ohkubo and Tibouchi recently presented structure-preserving signature schemes using Type 2 pairings. The schemes are claimed to enjoy the fastest signature verification. By properly accounting for subgroup membership testing of group elements in signatures, we show that the schemes are not as efficient as claimed. We presen
Multi-probe analysis of the galaxy cluster CL J1226.9+3332: Hydrostatic mass and hydrostatic-To-lensing bias
The precise estimation of the mass of galaxy clusters is a major issue for cosmology. Large galaxy cluster surveys rely on scaling laws that relate cluster observables to their masses. From the high-resolution observations of ∼45 galaxy clusters with the NIKA2 and XMM-Newton instruments, the NIKA2 Sunyaev-Zela'dovich Large Program should provide an accurate scaling relation between the thermal Sunyaev-Zela'dovich effect and the hydrostatic mass. In this paper we present an exhaustive analysis of the hydrostatic mass of the well-known galaxy cluster CL J1226.9+3332, the highest-redshift cluster in the NIKA2 Sunyaev-Zela'dovich Large Program at z=0.89. We combined the NIKA2 observations with thermal Sunyaev-Zela'dovich data from the NIKA, Bolocam, and MUSTANG instruments and XMM-Newton X-ray observations, and tested the impact of the systematic effects on the mass reconstruction. We conclude that slight differences in the shape of the mass profile can be crucial when defining the integrated mass at R500, which demonstrates the importance of the modelling in the mass determination. We prove the robustness of our hydrostatic mass estimates by showing the agreement with all the results found in the literature. Another key factor for cosmology is the bias of the masses estimated assuming the hydrostatic equilibrium hypothesis. Based on the lensing convergence maps from the Cluster Lensing And Supernova survey with Hubble (CLASH) data, we obtain the lensing mass estimate for CL J1226.9+3332. From this we are able to measure the hydrostatic-To-lensing mass bias for this cluster, which spans from 1-bHSE/lens∼0.7 to 1, presenting the impact of data sets and mass reconstruction models on the bias
NIKA2 observations of dust grain evolution from star-forming filament to T-Tauri disk: Preliminary results from NIKA2 observations of the Taurus B211/B213 filament
To understand the evolution of dust properties in molecular clouds in the
course of the star formation process, we constrain the changes in the dust
emissivity index from star-forming filaments to prestellar and protostellar
cores to T Tauri stars. Using the NIKA2 continuum camera on the IRAM 30~m
telescope, we observed the Taurus B211/B213 filament at 1.2\,mm and 2\,mm with
unprecedented sensitivity and used the resulting maps to derive the dust
emissivity index . Our sample of 105 objects detected in the map
of the B211/B213 filament indicates that, overall, decreases from
filament and prestellar cores () to protostellar cores
() to T-Tauri protoplanetary disk (). The
averaged dust emissivity index across the B211/B213 filament exhibits a
flat () profile. This may imply that dust grain sizes are
rather homogeneous in the filament, start to grow significantly in size only
after the onset of the gravitational contraction/collapse of prestellar cores
to protostars, reaching big sizes in T Tauri protoplanetary disks. This
evolution from the parent filament to T-Tauri disks happens on a timescale of
about 1-2~Myr.Comment: to appear in Proc. of the mm Universe 2023 conference, Grenoble
(France), June 2023, published by F. Mayet et al. (Eds), EPJ Web of
conferences, EDP Science
IAS/CEA Evolution of Dust in Nearby Galaxies (ICED): the spatially-resolved dust properties of NGC4254
We present the first preliminary results of the project \textit{ICED},
focusing on the face-on galaxy NGC4254. We use the millimetre maps observed
with NIKA2 at IRAM-30m, as part of the IMEGIN Guaranteed Time Large Program,
and of a wide collection of ancillary data (multi-wavelength photometry and gas
phase spectral lines) that are publicly available. We derive the global and
local properties of interstellar dust grains through infrared-to-radio spectral
energy distribution fitting, using the hierarchical Bayesian code HerBIE, which
includes the grain properties of the state-of-the-art dust model, THEMIS. Our
method allows us to get the following dust parameters: dust mass, average
interstellar radiation field, and fraction of small grains. Also, it is
effective in retrieving the intrinsic correlations between dust parameters and
interstellar medium properties. We find an evident anti-correlation between the
interstellar radiation field and the fraction of small grains in the centre of
NGC4254, meaning that, at strong radiation field intensities, very small
amorphous carbon grains are efficiently destroyed by the ultra-violet photons
coming from newly formed stars, through photo-desorption and sublimation. We
observe a flattening of the anti-correlation at larger radial distances, which
may be driven by the steep metallicity gradient measured in NGC4254.Comment: to appear in Proc. of the mm Universe 2023 conference, Grenoble
(France), June 2023, published by F. Mayet et al. (Eds), EPJ Web of
conferences, EDP Science
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