共查询到20条相似文献,搜索用时 0 毫秒
1.
O. Vaduvescu M. Popescu I. Comsa A. Paraschiv D. Lacatus A. Sonka A. Tudorica M. Birlan O. Suciu F. Char M. Constantinescu T. Badescu M. Badea D. Vidican C. Opriseanu 《Astronomische Nachrichten》2013,334(7):718-728
The ESO/MPG WFI and the INT WFC wide field archives comprising 330 000 images were mined to search for serendip‐itous encounters of known Near Earth Asteroids (NEAs) and Potentially Hazardous Asteroids (PHAs). A total of 152 as‐teroids (44 PHAs and 108 other NEAs) were identified using the PRECOVERY software, their astrometry being measured on 761 images and sent to the Minor Planet Centre. Both recoveries and precoveries were reported, including prolonged orbital arcs for 18 precovered objects and 10 recoveries. We analyze all new opposition data by comparing the orbits fitted before and after including our contributions. We conclude the paper presenting “Mega‐Precovery”, a new online service focused on data mining of many instrument archives simultaneously for one or a few given asteroids. A total of 28 instrument archives have been made available for mining using this tool, adding together about 2.5 million images forming the “Mega‐Archive” 相似文献
2.
A.D. Wittmann 《Astronomische Nachrichten》2003,324(4):378-380
Measurements of the solar diameter using both visual and photoelectric drift scan techniques have been made since 1972 using two almost identical 45‐cm Gregory‐Coudé telescopes at Locarno/Switzerland and Izaña/Tenerife. The method, in which a time measurement substitutes an angular measurement, is especially suited to obtain about 30 measurements of the absolute solar semidiameter per day. During the years 1972–2002 a total of 10996 visual timing measurements have been made on 320 observing days, an additional 1373 photoelectric recordings have been obtained on 117 observing days. The data were used to study the long‐term behaviour of the solar semidiameter R at unit distance and its possible variations. No fluctuations dR in excess of about ±0.05″ have been found, neither long‐term nor short‐term. The photoelectric semidiameter, which refers to the continuum at λ ≈ 585 nm, is Rphot = (959.89 ± 0.12)″. The visual semidiameter, which refers to the footpoint of the limb intensity profile at λ ≈ 550 nm, is Rvis = (960.62 ± 0.02)″. 相似文献
3.
M. J. Lehner C. Alcock T. Axelrod F. Bianco Y.‐I. Byun W.‐P. Chen K. H. Cook R. Dave I. de Pater J. Giammarco S.‐K. King T. Lee J. Lissauer S. L. Marshall S. Mondal T. Nihei J. Rice M. Schwamb A. Wang S.‐Y. Wang C.‐Y. Wen Z.‐W. Zhang 《Astronomische Nachrichten》2006,327(8):814-817
The Taiwanese‐American Occultation Survey (TAOS) seeks to determine the number and size spectrum for small (∼3 km) bodies in the Kuiper Belt. This will be accomplished by searching for the brief occultations of bright stars (R ∼ 14) by these objects. We have designed and built a special purpose photometric monitoring system for this purpose. TAOS comprises four 50 cm telescopes, each equipped with a 2048 × 2048 pixel CCD camera, in a compact array located in the central highlands of Taiwan. TAOS will monitor up to 2 000 stars at 5 Hz. The system went into scientific operation in the autumn of 2005. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
4.
The eSTAR Project uses intelligent agent technologies to carry out resource discovery, submit observation requests and analyze the reduced data returned from a meta‐network of robotic telescopes. Linking ground based telescopes with astronomical satellites, and using the emerging field of intelligent agent architectures to provide crucial autonomous decision making in software, the project has succeeded in combining data archives and research class telescopes, along with distributed computing nodes, to build an ad‐hoc peer‐to‐peer heterogeneous network of resources. We present the current operations paradigm of the eSTAR network and describe the direction in which the project intends to develop over the next few years. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
5.
In this article we describe a case study of how NOAO is considering improving its management of Target‐of‐Opportunity (ToO) observations by integrating VOEvent into the flow of activities. We believe that using VOEvent to help document and track the use of ToO time will improve the user experience of ToOs at NOAO. It will also greatly aid in the management of the process and of the resulting data, allowing us to better track the ownership and provenance of the data and any resulting data products. Finally, it will provide an important method of archival access to the data and data “collections,” which might include not only processed data from a single VOEvent triggered observation but could also include multiple observations traceable to a single (or set of related) VOEvents. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
6.
C. Martayan A. Alvarez P. Bristow R. Castillo H. Dekker S. D'Odorico V. Mainieri E. Mason A. Modigliani S. Moehler P. Moller F. Patat E. Pena C. Reinero J. Vernet J. Vinther M. Vuckovic all the engineers who work a lot on X‐shooter 《Astronomische Nachrichten》2011,332(3):222-223
We report on the current performances and measurements done with X‐shooter during its first year of operations at Paranal. We present the current instrumental problems, recent and future improvements, and give advice for the observations (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
7.
N. Solomos 《Astronomische Nachrichten》2008,329(3):252-254
This contribution aims to introduce the idea that a well‐evolved HTN of the far future, with the anticipated addition of very large apertures, could also be made to incorporate the ability to carry out photonic astronomy observations, particularly Optical VLBI in a revived Hanbury‐Brown and Twiss Intensity Interferometry (HBTII) configuration. Such an HTN could exploit its inherent rapid reconfigurational ability to become a multi‐aperture distributed photon‐counting network able to study higher‐order spatiotemporal photon correlations and provide a unique tool for direct diagnostics of astrophysical emission processes. We very briefly review various considerations associated with the switching of the HTN to a special mode in which single‐photon detection events are continuously captured for a posteriori intercorrelation. In this context, photon arrival times should be determined to the highest time resolution possible and extremely demanding absolute time keeping and absolute time distribution schemes should be devised and implemented in the HTN nodes involved. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
8.
G. Miniutti D. R. Ballantyne S. W. Allen A. C. Fabian R. R. Ross 《Monthly notices of the Royal Astronomical Society》2006,371(1):283-292
The Parkes High-Latitude pulsar survey covers a region of the sky enclosed by Galactic longitudes 220° < l < 260° and Galactic latitudes | b | < 60°. The observations have been performed using the 20-cm multibeam receiver on the Parkes 64-m radio telescope. A total of 6456 pointings of 265 s each have been collected. The system adopted provided a sensitivity limit, for long-period pulsars with 5 per cent duty cycles, of ∼0.5 mJy. Data analysis resulted in the detection of 42 pulsars of which 18 were new discoveries. Four of these belong to the class of the millisecond – or recycled – pulsars; three of these four are in binary systems. The double pulsar system J0737−3039 is among those and has been presented elsewhere. Here, we discuss the other discoveries and provide timing parameters for the objects for which we have a phase-connected solution. 相似文献
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10.
D'Amico Stappers Bailes Martin Bell Lyne & Manchester 《Monthly notices of the Royal Astronomical Society》1998,297(1):28-40
The Parkes survey of the entire southern sky for millisecond and other low-luminosity pulsars has now been completed. The survey system and initial results were described by Manchester et al. and the final results and population studies are described by Lyne et al. A total of 298 pulsars were detected, including 101 new discoveries of which 17 were millisecond pulsars. Here we report on timing observations at Parkes and Jodrell Bank of the 84 long-period (non-millisecond) pulsars discovered in the survey, including timing solutions for 78 of them. Pulse profiles and arrival times were obtained at several different frequencies over intervals of more than a year, yielding a position, period, period derivative and dispersion measure for each pulsar. Pulse profiles at frequencies near 400 MHz and 600 or 1400 MHz are presented for most of the observed pulsars. Significant timing noise was detected for five pulsars and a glitch was observed in the period of PSR J1123–6259. 相似文献
11.
C. Mottram 《Astronomische Nachrichten》2006,327(8):806-810
We describe the current high level interfaces used for communicating with the Robonet‐1.0 Homogeneous Telescope Network. This is a network of three telescopes, the Liverpool Telescope and the Faulkes Telescopes (North and South). We describe our use of RTML and web‐services to enable control of the network by intelligent agents. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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Giovanni F. Gronchi 《Celestial Mechanics and Dynamical Astronomy》2005,93(1-4):295-329
We describe an efficient algorithm to compute all the critical points of the distance function between two Keplerian orbits
(either bounded or unbounded) with a common focus. The critical values of this function are important for different purposes,
for example to evaluate the risk of collisions of asteroids or comets with the Solar system planets. Our algorithm is based
on the algebraic elimination theory: through the computation of the resultant of two bivariate polynomials, we find a 16th
degree univariate polynomial whose real roots give us one component of the critical points. We discuss also some degenerate
cases and show several examples, involving the orbits of the known asteroids and comets.
相似文献
15.
O. I. Wong R. L. Webster V. A. Kilborn M. Waugh L. Staveley-Smith 《Monthly notices of the Royal Astronomical Society》2009,399(4):2264-2278
We present the Northern HIPASS (H i Parkes All-Sky Survey) Optical/Infrared Catalogue (NOIRCAT), an optical/near-infrared (NIR) counterpart to the Northern HIPASS Catalogue (NHICAT). Of the 1002 sources in NHICAT, 655 (66 per cent) have optical counterparts with matching optical velocities. A further 85 (8 per cent) sources have optical counterparts with matching velocities from previous radio emission-line surveys. We find a correlation between the gas and stellar content of the NOIRCAT sources. Our H i -selected sample of isolated galaxies also presents a wider range in NIR colours than previous optically selected studies of regular, isolated galaxies. All H i detections in optically unobscured fields could be matched with either a NASA/IPAC Extragalactic Database optical counterpart, or a galaxy visible in Second Palomar Observatory Sky Survey or Digitized Sky Survey images. However, as over 200 of these matched galaxies have no velocity information, further follow-up observations are needed to confirm the matches, and hence confirm or deny the existence of dark galaxies in this data set. 相似文献
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17.
We have measured the right ascension of Geminga at different epochs by comparing the absolute phases between the different γ-ray observations. These values show that the right-ascension component of the proper motion of Geminga is 0.226±0.03 arcsec per year, which is consistent with that of G″, the most probable optical counterpart, thus independently confirming the correspondence between G″ and Geminga. 相似文献
18.
In order to study the statistical characters and physical significance of the color indexes and orbital parameters of Centaurs, we have analyzed the color and orbit parameter correlations by using statistical methods according to the known color indexes of 39 Centaurs and their respective orbital parameters. We find that all the correlations of B − V vs. V − R, V − R vs. R − I, B − V vs. R − I and B − R vs. R − I are strong. The Centaurs exhibit obvious redblue double-color property, and the point of demarcation is close to B − R = 1.4. The distributions of the various color indexes of Centaurs exhibit the normal distribution. For the correlations between colors and orbital parameters, except for the weak correlations between B − V and the orbital inclination i as well as between V − R and the orbital semi-major axis a, no evident correlation has been found between color indexes and orbital parameters. 相似文献
19.
C.‐I. Lagerkvist O. Karlsson G. Hahn St. Mottola A. Doppler A. Gndig U. Carsenty 《Astronomische Nachrichten》2002,323(5):475-483
We have used the ESO Schmidt telescope during the apparitions 1996, 1997 and 1998 to study the preceding Lagrangian cloud of Jupiter, L4. In our observed field of view, about 700 square degrees, during 1996 we found 399 moving objects that we classified as Trojans. From this we conclude that down to absolute magnitude H ≤ 13.0 there are ≈ 1100 Trojans in the L4 cloud. Proper elements of 696 numbered and multiopposition Trojans were calculated and one of these in the L5 cloud were found to be a non Trojan. A discussion of the Trojan proper elements is also presented. 相似文献
20.
M. Bro D. Vokrouhlický F. Roig D. Nesvorný W. F. Bottke A. Morbidelli 《Monthly notices of the Royal Astronomical Society》2005,359(4):1437-1455
The 2/1 mean motion resonance with Jupiter, intersecting the main asteroid belt at ≈3.27 au, contains a small population of objects. Numerical investigations have classified three groups within this population: asteroids residing on stable orbits (i.e. Zhongguos), those on marginally stable orbits with dynamical lifetimes of the order of 100 Myr (i.e. Griquas), and those on unstable orbits. In this paper, we reexamine the origin, evolution and survivability of objects in the 2/1 population. Using recent asteroid survey data, we have identified 100 new members since the last search, which increases the resonant population to 153. The most interesting new asteroids are those located in the theoretically predicted stable island A, which until now had been thought to be empty. We also investigate whether the population of objects residing on the unstable orbits could be resupplied by material from the edges of the 2/1 resonance by the thermal drag force known as the Yarkovsky effect (and by the YORP effect, which is related to the rotational dynamics). Using N -body simulations, we show that test particles pushed into the 2/1 resonance by the Yarkovsky effect visit the regions occupied by the unstable asteroids. We also find that our test bodies have dynamical lifetimes consistent with the integrated orbits of the unstable population. Using a semi-analytical Monte Carlo model, we compute the steady-state size distribution of magnitude H < 14 asteroids on unstable orbits within the resonance. Our results provide a good match with the available observational data. Finally, we discuss whether some 2/1 objects may be temporarily captured Jupiter-family comets or near-Earth asteroids. 相似文献