35,420 research outputs found
A 190 by 244 charge-coupled area image sensor with interline transfer organization
A 190 x 244 element charge coupled area image sensor has been designed, fabricated and tested. This sensor employs an interline transfer organization and buried n-channel technology. It features a novel on-chip charge integrator and a distributed floating gate amplifier for high and low light level applications. The X-Y element count has been chosen to establish the capability of producing an NTSC compatible video signal. The array size is also compatible with the Super 8 lens format. The first few sample devices have been successfully operated at full video bandwidth for both high and low light levels with the charge amplifier system
A star field mapping system for determining the attitude of a spinning probe
Astronomical mapping by rotating satellite to determine own angle of orientation to celestial spher
Structural sensitivity analysis: Methods, applications, and needs
Some innovative techniques applicable to sensitivity analysis of discretized structural systems are reviewed. These techniques include a finite-difference step-size selection algorithm, a method for derivatives of iterative solutions, a Green's function technique for derivatives of transient response, a simultaneous calculation of temperatures and their derivatives, derivatives with respect to shape, and derivatives of optimum designs with respect to problem parameters. Computerized implementations of sensitivity analysis and applications of sensitivity derivatives are also discussed. Finally, some of the critical needs in the structural sensitivity area are indicated along with Langley plans for dealing with some of these needs
Observations of Global and Local Infall in NGC 1333
We report ``infall asymmetry'' in the HCO (1--0) and (3--2) lines toward
NGC 1333, extended over , a larger extent than has been
reported be fore, for any star-forming region. The infall asymmetry extends
over a major portion of the star-forming complex, and is not limited to a
single protostar, or to a single dense core, or to a single spectral line. It
seems likely that the infall asymmetry represents inward motions, and that
these motions are physically associated with the complex. Both blue-asymmetric
and red-asymmetric lines are seen, but in both the (3--2) and (1--0) lines of
HCO the vast majority of the asymmetric lines are blue, indicating inward
motions. The (3--2) line, tracing denser gas, has the spectra with the
strongest asymmetry and these spectra are associated with the protostars IRAS
4A and 4B, which most likely indicates a warm central source is affecting the
line profiles. The (3--2) and (1--0) lines usually have the same sense of
asymmetry in common positions, but their profiles differ significantly, and the
(1--0) line appears to trace motions on much larger spatial scales than does
the (3--2) line. Line profile models fit the spectra well, but do not strongly
constrain their parameters. The mass accretion rate of the inward motions is of
order 10 M/yr, similar to the ratio of stellar mass to cluster
age.Comment: 28 pages, 11 figures, 1 colour figur
SOUTHERNMOST OCCURRENCE OF THE SUWANNEE COOTER, PSEUDEMYS CONCINNA SUWANNIENSIS (TESTUDINES: EMYDIDAE)
The Suwannee Cooter, Pseudemys concinna suwanniensis, the largest member of the speciose turtle family Emydidae, inhabits a small number of rivers that drain into the northeastern Gulf of Mexico along the northwest coast of Florida from just west of Tallahassee to just south of Tampa. The status of this state-protected subspecies in the southernmost of these rivers, the Alafia, is unknown and hence of conservation concern. We provide recent evidence confirming that a reproducing population still exists in this river, and review available specimens and both published and unpublished records documenting the southern limit of distribution. At least within the eastern United States, our observations also extend confirmed knowledge of the geographic occurrence of hatchling turtles overwintering in the nest southward by 285 km
Instrumentation for measurement of cosmic noise at 750, 1225, and 2000 kHz from a rocket Final technical report
Design and performance characteristics of rocketborne instrumentation system to measure radio frequency noise energ
The Local Group Census: planetary nebulae in Sextans B
Five planetary nebulae (PNe) have been discovered in the nearby dwarf
irregular galaxy. Emission line images were obtained using the Wide Field
Camera of the 2.5m Isaac Newton Telescope (INT) at La Palma (Spain). The
candidate PNe were identified by their point-like appearance and relatively
strong [OIII] emission-line fluxes. They are located within a galactocentric
distance of 2.8 arcmin, corresponding to 1.1 kpc at the distance of Sextans B.
Luminosities are in the range 1800--5600Lsolar. Sextans B is one of the
smallest dwarf irregular galaxies with a PN population. The number of PNe
detected suggest an enhanced star formation rate between 1 and 5 Gyr ago.Comment: 7 pages, 2 figure
3D Spectrophotometry of Planetary Nebulae in the Bulge of M31
We introduce crowded field integral field (3D) spectrophotometry as a useful
technique for the study of resolved stellar populations in nearby galaxies. As
a methodological test, we present a pilot study with selected extragalactic
planetary nebulae (XPN) in the bulge of M31, demonstrating how 3D spectroscopy
is able to improve the limited accuracy of background subtraction which one
would normally obtain with classical slit spectroscopy. It is shown that due to
the absence of slit effects, 3D is a most suitable technique for
spectrophometry. We present spectra and line intensities for 5 XPN in M31,
obtained with the MPFS instrument at the Russian 6m BTA, INTEGRAL at the WHT,
and with PMAS at the Calar Alto 3.5m Telescope. Using 3D spectra of bright
standard stars, we demonstrate that the PSF is sampled with high accuracy,
providing a centroiding precision at the milli-arcsec level. Crowded field 3D
spectrophotometry and the use of PSF fitting techniques is suggested as the
method of choice for a number of similar observational problems, including
luminous stars in nearby galaxies, supernovae, QSO host galaxies,
gravitationally lensed QSOs, and others.Comment: (1) Astrophysikalisches Institut Potsdam, (2) University of Durham.
18 pages, 11 figures, accepted for publication in Ap
The young massive stellar cluster associated to RCW121
We report NIR broad and narrow band photometric observations in the direction
of the IRAS17149-3916 source that reveal the presence of a young cluster of
massive stars embedded in an HII region coincident with RCW121. These
observations, together with published radio data, MSX and Spitzer images were
used to determine some of the physical parameters of the region. We found 96
cluster member candidates in an area of about 1.5 x 2.0 square arcmin, 30% of
them showing excess emission in the NIR. IRS 1, the strongest source in the
cluster with an estimated spectral type of O5V-O6V ZAMS based on the
color-magnitude diagram, is probably the main ionizing source of the HII region
detected at radio wavelengths. Using the integrated Brgamma and the 5 GHz flux
densities, we derived a mean visual extinction AV=5.49 magnitudes. From the
observed size of the Brgamma extended emission, we calculated the emission
measure E and the electron density ne, characteristic of compact HII regions.Comment: 18 pages, 8 figures, accepted for publication on AJ (February/2006
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