共查询到20条相似文献，搜索用时 187 毫秒
1.
Judith L. Pipher 《Experimental Astronomy》1994,3(1-4):1-8
Ten years ago, Forrest presented the first astronomical images with an SBRC 32×32 InSb array camera at the first NASA-Ames Infrared Detector Technology Workshop. Soon after, SBRC began development of 58×62 InSb arrays, both for ground-based astronomy and for SIRTF. By the time of the 1987 Hilo workshop Ground-based Astronomical Observations with Infrared Array Detectors astronomical results from cameras based on SBRC 32×32 and 58×62 InSb arrays, a CE linear InSb array, and a French 32×32 InSb CID array were presented. And at the Tucson 1990 meeting Astrophysics with Infrared Arrays, it was clear that this new technology was no longer the province of IR pundits, but provided a tool for all astronomers. At this meeting, the first astronomical observations with SBRC's new, gateless passivation 256×256 InSb arrays will be presented: they perform spectacularly!In this review, I can only broadly brush on the interesting science completed with InSb array cameras. Because of the broad wavelength coverage (1–5.5 m) of InSb, and the extremely high performance levels throughout the band, InSb cameras are used not only in the near IR, but also from 3–5.5 m, where unique science is achieved. For example, the point-like central engines of AGNs are delineated at L and M, and Br and 3.29 m dust emission images of galactic and extragalactic objects yield excitation conditions. Examples of imaging spectroscopy, high spatial resolution imaging, as well as deep, broad-band imaging with InSb cameras at this meeting illustrate the power of InSb array cameras. 相似文献
2.
D. C. Murphy 《Experimental Astronomy》1994,3(1-4):141-142
Tracing results for two designs based on the Offner reimager are given: a practical 256×256 NICMOS-3 IR/CCD I-K camera designed for use on a f/13.5 1-m telescope yielding a 154×154 field, and a hypothetical 1024×1024 pixel nextgeneration IR camera for a f/7.5 2.5-m telescope yielding a 244×244 field. Both designs produce near-diffration limited results. 相似文献
3.
M. E. McKelvey Robert E. McMurray Jr. C. R. Mccreight W. J. Forrest J. D. Garnett N. Lum J. Asbrock R. White R. Kelchner L. Lum L. Pham 《Experimental Astronomy》1994,3(1-4):167-168
256×256-element IBC Si:As arrays have been evaluated for applications in IR astronomy from space-borne platforms. Basic figures of merit were measured at IR flux levels simulating those expected in space-based astronomical observations. Results include dark current <20e
-/s, G as high as 3.8, / of 20%, and read noise below 100 rms e-. 相似文献
4.
A study of the galactic structure has been made by deriving the brightness distribution of the galactic plane at 2.2 m and 4.2 m near infrared region using infrared objects detected by ground-based sky surveys. The infrared brightness distribution shows distinct peaks at every 8–12° galactic longitude and indicates a periodic structure. The one-to-one positional correlation observed between the periodic structure in 2.2 m infrared brightness and the 2.6 mm CO emission line suggests that the near-infrared sources are strongly associated with dense clouds of molecular hydrogen distributed in the galactic plane. 相似文献
5.
We present near infrared maps of the planetary nebula IC 418 taken at 5 arc sec spatial resolution. These show an extremely compact source structure at 1.65 m, and very much broader and more elliptical emission distributions at 2.2 and 3.6 m. The possibility that the near infrared continuum derives from small grains with low thermal capacity is discussed, and synthetic spectra are derived. These indicate a very much slower variation of flux with wavelength than would be deduced for grains at unitary temperature, and imply a near infrared continuum which is significantly cooler than maximum grain temperatures. Fits to the spectrum of IC 418 suggest that peak grain temperatures may approachT
p0103 K (for –2), for instance, compared to the observed colour temperature of 650 K.Finally, the relevant grains are required to be refractory and, given the large C/O ratio in this nebula, probably consist of graphite. Their mass is also required to be small, and is probably of order 2×10–7
M
. This compares with the probable total mass for large dust grains of 10–4
M
. Although they are both small and warm, such grains would be expected to persist over the lifetime of the nebula, and may also be responsible for various NIR band emission features. 相似文献
6.
Isabelle Vauglin 《Astrophysics and Space Science》1990,171(1-2):275-278
We describe three recent infrared cameras, developed in France and based on mosaïcs of infrared detectors. They are optimized for ground-based observations in the 1–5 m or 5–17 m ranges. The results already obtained, emphasize the interest of studying the sky in that domain.Paper presented at the 11th European Regional Astronomical Meetings of the IAU on New Windows to the Universe, held 3–8 July, 1989, Tenerife, Canary Islands, Spain. 相似文献
7.
F. Lisi C. Baffa L. Hunt R. Maiolino G. Moriondo R. Stanga 《Experimental Astronomy》1994,3(1-4):130-132
ARNICA (ARcetri Near Infrared CAmera) is the imaging camera for the near infrared bands between 1.0 and 2.5 m that Arcetri Observatory has designed and built as a common use instrument for the TIRGO telescope (1.5 m diameter, f/20) located at Gornergrat (Switzerland). The scale is 1 per pixel, with sky coverage of more than 4×4 on the NICMOS 3 (256×256 pixels, 40 m side) detector array. The optical path is compact enough to be enclosed in a25.4 cm diameter dewar; the working temperature of detector and optics is 76 K. We give an estimate of performance, in terms of sensitivity with an assigned observing time, along with some preliminary considerations on photometric accuracy. 相似文献
8.
Mark Shure D. W. Toomey John Rayner P. Onaka A. Denault W. Stahlberger D. Watanabe K. Criez L. Robertson D. Cook M. Kidger 《Experimental Astronomy》1994,3(1-4):239-242
We have just finished building a 1.0–5.5 m infrared array camera for the NASA Infrared Telescope Facility based upon the SBRC 256×256 InSb array. After a brief overview of the capabilities of the camera (named NSFCAM), we present some of the first images obtained with this new camera, including results obtained with our realtime shift & add speckle imaging mode. 相似文献
9.
We discuss imaging with arrays in the thermal IR. Aspects of the design and performance of the Golden Gopher, an infrared array camera are presented. This instrument operates in a high-background environment, for ground-based astronomical imaging from 5 to 27 m. It is built around a 20×64 element Si:As Impurity Band Conduction (IBC) device manufactured by GenCorp Aerojet Electronic Systems Division, and has a noise-equivalent flux density (NEFD) of 23.5mJy min
-1/2 arcsec-2 at =10m, =1m, on the Mt. Lemmon 1.5m telescope. We present and discuss a sample of the data. In addition we discuss the design and expected performance of the Long Wavelength Spectrometer which is now under construction for the Keck telescope. 相似文献
10.
The Hughes Technology Center (HTC) has developed a family of high-performance Si:As impurity-band conduction (IBC) hybrid focal plane arrays (FPAs) optimized for low background applications: 58×62 pixels (76-m pitch), 128×128 pixels (75- and 120-m pitch), and 256×256 pixels (30-m pitch). These FPAs exhibit state-of-the-art low noise (<100e
-) achieved by using readout arrays fabricated on HTC's CryoCMOS process line. The IBC detector arrays, also fabricated at HTC, exhibit high quantum efficiency over a wide waveband with operating temperature of 4–12 K. In addition, Hughes is developing a 256×256 Si:As IBC FPA for high background applications as well as a 512×512 FPA. Readout development includes design and fabrication of 256×256 readouts with large well size of 1×107
e
- for the high-background FPA and 512×512 readouts with moderate well size (1×106
e
-). 相似文献
11.
, () , , ( =2) , . (, , ). ( =0,5) . 相似文献
12.
13.
We investigate further the interpretation of dark magnetic faculae observed in previous imaging of the solar photosphere at 1.63 m. We show that their contrast at 1.63 m increases with magnetic flux beyond a threshold value of 2 × 1018 Mx and blends smoothly with the contrast vs flux relation measured at this wavelength for larger structures of sunspot size. Not all facular structures that are bright in Ca K are dark at 1.63 m, apparently because their magnetic flux is not large enough. After correction for blurring, the contrast of the dark faculae observed near the disc center at 1.63 m is approximately 4%. But our observations at 1.23 m, which probe slightly higher photospheric levels, do not show these dark faculae. These results indicate that magnetic flux tubes of diameter as small as 500 km significantly inhibit convective heat flow to the photosphere, much as do sunspot flux tubes of much larger diameter. They also suggest that, in even smaller flux tubes, the inhibition becomes rapidly less significant. Finally, we show that the sunspot-size dependence of umbral infrared contrast versus wavelength that we observe can probably be explained in terms of instrumental blurring. Observations with lower scattered light will be required to determine whether a real decrease of contrast with diameter also plays a role. 相似文献
14.
. - . . , . - . - , , , -. ., , .
English translation will appear in the next issue ofAstrophys. Space Sci.
Receipt delayed by postal strike in Great Britain 相似文献
The structure of rotating magnetic polytropes is considered in Roche approximation. Investigation of the influence of poloidal as well as toroidal magnetic fields on the conditions of the beginning of matter outflow due to rotational instability is carried out. The influence of the turbulent convection and twisting of magnetic force-lines on the time of smoothing of differential rotation is considered. The estimate of the magneto-turbulence energy generated by differential rotation is presented. Both maximum possible energy output and duration of the quasi-statical evolution phase up to the appearance of hydrodynamic instability due to the effects of general relativity are calculated for supermassive magnetic polytropes of index three with uniform or differential rotation. The radius-mass relation is obtained for supermassive differentially-rotating magnetic polytropes referring to the longest part of the quasi-statistical evolution stage; some consequences are pointed out, including the period-luminosity relation.The evolution of the considered models of supermassive rotating magnetic polytropes with different character of rotation and different geometry of a magnetic field is discussed.The results obtained are summarized in the last section.
English translation will appear in the next issue ofAstrophys. Space Sci.
Receipt delayed by postal strike in Great Britain 相似文献
15.
Г. А. Гурзадян 《Astrophysics and Space Science》1979,64(1):3-23
2800 Mgii (. 1). (N
+/N
11000) , , (N
+/N
110). , . —, , . — . : ; 0.002 1 , 0.1 ; () 100 –3; ; ; , 10
; 10–4
1
. 2800 Mgii . 相似文献
16.
The normalised Hénon–Heiles family exhibits a degenerate bifurcation when passing through the separable case =0. We clarify the relation between this degeneracy and the integrability at =0. Furthermore we show that the degenerate bifurcation carries over to the Hénon–Heiles family itself. 相似文献
17.
В. А. Гаген-Торн 《Astrophysics and Space Science》1980,73(2):279-294
J 287 1972–1976. , . . J ( ), () . (0=80°) . J 287 ¶ . p=42.8%, 0=101°. (50%). 相似文献
18.
A. M. I. Osman 《Astrophysics and Space Science》1985,116(2):299-311
Surface photometry of the UV continuum galaxy NGC 838 has been carried out in theB, V system using photographic plates obtained with the 74 Kottamia telescope, Egypt. Isophotes, luminosity profiles, integrated photographic magnitudes, effective diameters and other photometric parameters are derived.The photoelectrically calibrated total apparent magnitudes areB
T
=13.57 with maximum diameters 1.57×1.34 (at threshold
m
=27.7 mag.//) andV
T
=12.91 with maximum diameters 1.54×1.32 (at threshold
m
=27.7 mag./). The integrated colour index(B–V)
T
=0.66 and the effective surface brightness
e
(B=19.0 mag./) and
e
(V=19.7 mag./. The major axis is at position angle =85°±1°.The nucleus of NGC 838 is quite blue (integrated colour(B–V)=0.41 forr
*<0.1) compared to normal galaxies while the colour becomes redder from the nucleus outwards. The UV excess, H emission and radio continuum emission previously observed from this galaxy by other investigators may be attributed to a recent burst of star formation in the nucleus of the galaxy of duration slightly greater than 2×107 yr. 相似文献
19.
A. S. Baranov 《Celestial Mechanics and Dynamical Astronomy》1979,20(3):251-270
Periodic orbits of stars in axisymmetrical nearly spherical stellar systems have been investigated. Generating orbits have been found among periodic ones relating to the spherically-symmetrical field. The linear approximation appears to be insufficient for constructing periodic trajectories. Possible variants of the generating periodic solutions have been found, which give rise to disturbed periodic orbits in the second approximation.
, . - . , . , .相似文献
20.
Г. И. Ширмин 《Celestial Mechanics and Dynamical Astronomy》1975,11(4):483-515
1937 - (, 1938). , , , , . , . . (, 1938), , . - (, 1938; Szebehely, 1967)., , . . - (, 1938), . — — . , , . , . . , . , , . . (, 1944). , .
In 1937, the Celestial Mechanics and Cosmogony section of the Sternberg State Astronomical Institute undertook the task of evaluating the Gylden-Moulton hypothesis on the origin of the Gegenshein from the standpoint of celestial mechanics. That investigation, which the authors themselves considered preliminary, contains nonetheless a series of important results. For example, G. N. Duboshin showed that in the planar, circular, restricted three-body problem, periodic motion of finite amplitude in the neighborhood of a collinear libration point is unstable according to Lyapunov's criterion both in the proper and in the orbital sense. The latter result is incompatible with the above named hypothesis, and thus appears as one of the serious objections among the many known negative conclusions relative to the existence of the Gylden-Moulton cluster.Unfortunately, most of the specific problems which arose in the above named research have not been considered since. One of these, the problem of the stability of three-dimensional periodic orbits in the neighborhood of a collinear libration point is solved in the present paper, within the limits of the three-dimensional, circular, restricted, three-body problem. Major attention is given to the investigation of stability in the orbital sense, since in the proper sense all orbits are unstable according to Lyapunov theory. It is shown that in order to resolve the question of stability, it is sufficient to consider the equations in their variational form. Analysis of the roots of the corresponding characteristic equations determines the orbital stability of planar and three-dimensional solutions, which later can be confirmed by calculation of the characteristic exponents appearing in the periodic solutions of the N. A. Artemiev method. Finally, the possibility of conditional stability in the linear approximation is proved.相似文献