首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 109 毫秒
1.
In less than a decade, infrared array detectors have revolutionized infrared astronomy. Most of us remember using single element photometers in the early eighties, yet today, most of us are using 256×256 pixel arrays. At this meeting we have heard of plans to fabricate 1024×1024 arrays in the near infrared. From one to one million pixels in such a short period of time is amazing. The new array technology has also stimulated the development of many varieties of infrared cameras and spectrometers. At the UCLA Infrared Imaging Detector Lab we have commissioned two near infrared imaging systems (KCam and Gemini) based on 256×256 arrays and a spectrometer design study is in progress for 1024×1024 arrays. Performance of these cameras on the telescope will be reported briefly.  相似文献   

2.
The first 128×128 Si:Sb blocked impurity band (BIB) detectors, manufactured by Rockwell International, are sensitive detectors from 10 to at least 40 m. While further work is required to make these arrays suitable for the low backgrounds of space infrared telescopes, they can be used now for observations from the ground and aircraft.  相似文献   

3.
As modern infrared arrays evolve towards larger formats and smaller pixel sizes, their use in instruments requires optics of increasingly higher performance. Refractive systems are attractive for many applications because they can accommodate wide fields of view or fast focal ratios while permitting a compact, unobscured layout. We examine design considerations for lenses which can address the entire near-infrared spectral region of 0.8 to 2.5 m. Achromatization over this broad range is a particular challenge. We discuss a systematic study of candidate materials and combinations of materials having useful chromatic properties, with particular emphasis on alkaline earth halides and metallic oxides. We present an example of a practical design being incorporated into an instrument currently under construction.  相似文献   

4.
Since 1984, the CEA-LETI-LIR (Infrared Laboratory) has been involved in development of Si:Ga/DRO hybrid detector arrays dedicated to imaging of astronomical sources in the 8–13 m range. Successively, 32×32 element arrays were successfully manufactured for the ISOCAM camera and 64×64 arrays were fabricated for ground-based imaging. The latter detectors have been integrated in 3 cameras (C10, CAMIRAS and TIMMI for ESO) and have led to excellent astrophysical results since 1990.To equip instruments to be mounted on very large telescopes such as the European VLT at ESO, manufacture of new arrays has been undertaken and is currently under way at CEA-LETI-LIR. These new arrays will have a 128×192 format and will present the outstanding essential feature that their storage capacity will be able to be changed according to observation conditions (2 capacities will be implemented in the pixel).The main characteristics of these new detectors will be presented in this paper.  相似文献   

5.
The Gemini Telescopes are being built to exploit the splendid infrared sites of Mauna Kea in Hawaii and Cerro Pachon in Chile. Both telescopes are being designed to deliver 0.1 arcsecond images at 2.2 m to the focal plane. This image size includes all tracking and enclosure effects. To exploit the superb infrared characteristics of the sites and telescopes we will require a new generation of IR instruments which will challenge both instrument designers and infrared array technologies.  相似文献   

6.
The development of arrays which operate at wavelengths longer than 8 m has opened up new possibilities for imaging and spectroscopy but offers challenges not present at shorter wavelengths. Impurity Band Conduction (IBC) or Blocked-Impurity-Band (BIB) detectors can meet these challenges and offer numerous advantages over standard photoconductors. We review some of the general operating principles of these devices and discuss the current state of technology. We then discuss the requirements placed on mid-infrared arrays by groundbased, airborne and spacebased astronomy.  相似文献   

7.
Nested thin foil reflectors have made possible light weight, inexpensive and fast grazing incidence X-ray mirrors for astronomical spectroscopy over a broad band. These mirrors were developed at Goddard for the US Shuttle program and were flown on NASA's shuttleborne Astro-l mission in December 1990. Presently, the Japan/US collaborative spectroscopic mission ASCA, nearing its third year of successful operation in earth orbit, carries, four such mirrors, weighing less than 40 kg and giving total effective areas of 1200 and 420 cm2 at l and 8 keV respectively. The 420 kg observatory is the best possible example of how conical foil mirrors opened areas of research that could not have been otherwise addressed with available resources. In this paper, we will briefly review the development and performance of our first generation foil mirrors. We will also describe progress toward improving their imaging capability to prime them for use in future instruments. Such a goal is highly desirable, if not necessary for this mirror technology to remain competitive for future applications.  相似文献   

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   

9.
The development of high-contrast capabilities has long been recognized as one of the top priorities for the VLTI. As of today, the VLTI routinely achieves contrasts of a few 10??3 in the near-infrared with PIONIER (H band) and GRAVITY (K band). Nulling interferometers in the northern hemisphere and non-redundant aperture masking experiments have, however, demonstrated that contrasts of at least a few 10??4 are within reach using specific beam combination and data acquisition techniques. In this paper, we explore the possibility to reach similar or higher contrasts on the VLTI. After reviewing the state-of-the-art in high-contrast infrared interferometry, we discuss key features that made the success of other high-contrast interferometric instruments (e.g., integrated optics, nulling, closure phase, and statistical data reduction) and address possible avenues to improve the contrast of the VLTI by at least one order of magnitude. In particular, we discuss the possibility to use integrated optics, proven in the near-infrared, in the thermal near-infrared (L and M bands, 3-5 \(\upmu \)m), a sweet spot to image and characterize young extra-solar planetary systems. Finally, we address the science cases of a high-contrast VLTI imaging instrument and focus particularly on exoplanet science (young exoplanets, planet formation, and exozodiacal disks), stellar physics (fundamental parameters and multiplicity), and extragalactic astrophysics (active galactic nuclei and fundamental constants). Synergies and scientific preparation for other potential future instruments such as the Planet Formation Imager are also briefly discussed. This project is called Hi-5 for High-contrast Interferometry up to 5 μm.  相似文献   

10.
CATSAT is a small, fast and cheap space mission currently funded for Phase A studies under the Student Explorer Demonstration Initiative (STEDI) by University Space Research Association. Its prime scientific objective is to determine burst distances by measuring their spectra at energies from < 500 eV to several MeV. Soft X-ray spectral measurements will be made with 2 cm2 Si Avalanche Photodiodes (APD). The spectrometer will consist of seven collimated arrays, each containing 14 APDs and covering 1 steradians. CATSAT also contains three other context instruments. The Directional Gamma Spectrometer is a NaI-PMT array which will provide burst triggering as well as spectra and directional information from > 200 keV observations. The Hard X-Ray spectrometer consists of CaF2(Eu)-PMT detectors which are optimized in the cyclotron absorption energy band. The X-ray Albedo Polarimeter consists of nine collimated NaI-PMT detectors observing the earth reflected emission. Results from the XAP will be used to determine the burst direction and to place constraints on X-ray polarization. CATSAT was designed at three universities to be built with student help in two years for a cost of $3.5M.  相似文献   

11.
The calculated band positions and intensity factors for the bands of the infraredA-X transition of A10, suggest that an investigation for the infrared bands in the 1 to 5 m region of the spectra of Mira stars and M supergiants, along with the blue-green (B-X) bands, could provide clues to the Mira phenomena. The need for additional laboratory investigation of the infrared electronic transition is emphasized.  相似文献   

12.
The infrared properties of dust in space, as inferred from infrared observations at low to moderate spectral resolution at wavelengths 30 m are summarized. Condensates at high temperature: featureless material and silicon carbide; moderate temperature: silicates; and low temperature — ices are briefly discussed. Strong band emission from as yet unknown species has been detected in a variety of objects. Episodes of rapid dust formation have been recorded in the infrared spectra of certain eruptive variable stars, including classical novae. Observations of this class of objects promises to provide information on grain nucleation and growth.Invited contribution to the Proceedings of a Workshop onThermodynamics and Kinetics of Dust Formation in the Space Medium held at the Lunar and Planetary Institute, Houston, 6–8 September, 1978.  相似文献   

13.
T Tauri stars are young stars usually surrounded by dusty disks similar to the one from which we believe our own Solar System formed. Most T Tauri stars exhibit a broad emission or absorption band between 7.5 and 13.5µm which is attributed to silicate grains in the circumstellar environment. We imaged three spatially resolved T Tauri binaries through a set of broadband filters which include the spectral region occupied by the silicate band. Two of these objects (T Tauri and Haro 6–10) are infrared companion systems in which one component is optically much fainter but contributes strongly in the infrared. Both infrared companions exhibit a deep silicate absorption which is not present in their primaries, indicating that they suffer very strong local extinction which may be due to an edge-on circumstellar disk or to a dense shell. We also took low resolution spectra of the silicate feature of two unresolved T Tauris to look for narrow features in the silicate band which would indicate the presence of specific minerals such as olivine. We observed GK Tau, for which Cohen and Witteborn (1985) reported a narrow emission feature at 9.7µm, but do not find evidence for this feature, and conclude that it is either time-dependent or an artifact of absorption by telluric ozone.Paper presented at the Conference onPlanetary Systems: Formation, Evolution, and Detection held 7–10 December, 1992 at CalTech, Pasadena, California, U.S.A.  相似文献   

14.
Infrared spectra of submicrometre-sized particles of several protosilicates have been used to derive mass absorption coefficients. These data have been applied in order to describe the infrared radiation from the source OH 26.5+0.6 in terms of a simple model. A good fit of the 10 m absorption feature could be achieved, but some discrepancies remain in the 20 m region. The reasons for the weakness of the 20 m band in infrared sources are discussed.The laboratory spectra revealed that the samples contained a small admixture of carbonates. Thus, some statements about the infrared spectrum of submicrometre-sized carbonate particles could also be made.  相似文献   

15.
For 22 infrared sources showing the 10-m silicate absorption band, the optical depths, dust temperatures and equivalent widths have been calculated for two assumed simple models.  相似文献   

16.
It is shown that Mie theory predictions of extinction for pure water-ice with the optical constant measured at 100 K do not fit in detail the observed ice absorption feature in infrared objects, although we attempt to explain the observations by considering size distribution and shape of the grains.In addition, based on a similarity between the ice band and the absorption band found in carbon stars, we feel it is questionable whether or not the ice band can really be attributed to the interstellar water-ice.  相似文献   

17.
The H observations of a selected sample of bright Be stars are presented. The available infrared observations at K band (2.2 m) of these stars have been used to find the infrared excess emission. The analysis of the combined data show thatL H, the luminosity of the H emission line, is proportional toL IR, the luminosity of the infrared excess emission. The linear correlation betweenL IR andL H shows that both the infrared excess and the H line originate in a common region. It is also detected that the infrared excess emission is produced throughout the whole envelope whereas the H is emitted in some defined region of the circumstellar (CS) envelope.  相似文献   

18.
A search (using the Infrared Astronomical Satellite IRAS point source catalogue) for infrared counterparts of the fourteen new candidates for planetary nebulae of low surface brightness detected by Hartl and Tritton (1985), resulted in only five identifications. The infrared sources of four of these candidate nebulae are found within 5 are sec of their optical position and the fifth one within 1 are min. Two of the five nebulae identified with infrared sources are classified as true, one as probable and two as possible by Hartl and Tritton (1985). All the five nebulae are found in regions of high cirrus flux at 100 m. These nebulae are all found to have both point sources as well as small size extended sources (in the IRAS scan windows centred on the sources), with numbers varying from field to field. The infrared emission from these nebulae have dust temperatures 100K (characteristic of planetary nebulae). Four of the nebulae appear to be faint in the infrared (just as in the optical band) with total infrared flux of 2×10–13 W m–2. Only the PN candidate No. 12 appears to be very bright in the infrared. It is likely that part of the emission is from extraneous sources in the line-of-sight to the nebula.  相似文献   

19.
A new near infrared spectrophotometer has been built for the Asiago 182 cm telescope. The instrument performs both large band JHKLM photometry and 1–5 spectrophotometry; a tracking system on a field star allows closed loop mapping. The design and performances are discussed.  相似文献   

20.
The Space InfraRed Telescope Facility (SIRTF) is the fourth and finalelement in NASA's family of orbiting Great Observatories. SIRTFconsists of a 0.85-meter diameter telescope and three cryogenically-cooledscience instruments capable of observing from the near- to the far-infrared,between 3 and 180 m. Incorporating the latest in large-format infrareddetector arrays, SIRTF offers orders-of-magnitude improvements in capabilityover existing facilities. Launch is scheduled for December 2001, with ananticipated lifetime of up to 5 years. SIRTF will observe targets rangingfrom small, icy bodies in the outer Solar System to the most luminousknown objects in the distant reaches of the Universe. SIRTF representsan important scientific and technical bridge to NASA's new Origins program,and is managed for NASA by the Jet Propulsion Laboratory, CaliforniaInstitute of Technology.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号