共查询到19条相似文献，搜索用时 156 毫秒
1.
2.
介绍了一种对2台步进电机相互间采取等差角同步旋转的控制方案.根据这个方案设计和制作的机电控制电路实现了同步旋转快门功能,最终的同步精度控制在步进电机的性能1.8度/步的范围内,应用在激光测距系统中起到了安全保护单光子探测器的作用. 相似文献
3.
4.
2011年,美国、中国和俄罗斯等国都开展了多项空间探测与科学观测活动,发射了月球探测器、木星探测器等,尤其是由于2011年有火星探测器发射窗口,所以进行了两次重要的火星探测器发射,但有喜有悲：携带了世界最先进火星车“好奇号”的美国“火星科学实验室”顺利升空,并奔向火星;而携带了中国首个火星探测器“萤火-1”的俄罗斯的“火卫一-土壤”探测器虽然发射成功,但由于探测器本身故障而无法进入地火转移轨道,导致该任务失败。 相似文献
5.
《天文爱好者》2001,(5)
中国天文学名词审定委员会李启斌主任最近致函本编辑部 “由于空间探测器的新闻性极强,一旦发射,新闻媒体争相报道。所用译名往往不规范、不统一,给读者带来很多不便甚至误解。而一种译名一旦用惯,改起来就难了。如果在发射之前,提出推荐译名,便可避免此弊。为此天文学名词审定委员会在2000年11月召开的第17次审定会对近五年中将要发射(包括发射计划尚不十分确切)的空间天文探测器名称提出了推荐译名,共35条,此外还有两条是近年已经发射、而尚未推荐译名的两个空间探测器的译名。现送上,供试用,并请读者对译名提出改进意见。有些探测器还会在研制或发射过程中甚至发射后更改名称,因此,本委员会将在这些探测器发射以后,过一段时间,再做最后审定。” 现将这些推荐译名公布于下。 相似文献
6.
在高精度星地激光时间比对中,为了降低星载设备的研制难度,采用了无门控星载激光探测器。根据星地先验钟差、卫星距离和系统延迟量,精确计算地面激光发射时刻,使得激光信号能在星载计时器星钟开门信号之后短时间内到达星载探测器,使星载计时器关门,这样可以大大降低背景噪声影响,获得有效数据。该文研究了精确控制地面激光发射时刻的方法,包括激光发射时刻计算和激光控制器硬件的实现,该方法已在星地激光时间比对在轨试验中得到了成功应用,控制精度在20ns以内,满足了试验的要求。 相似文献
7.
8.
中国首个火星探测器萤火1号拟定在2011年发射升空。探测器上配备了一组(2个)超稳定晶体振荡器,该组晶体振荡器为X波段发射机提供频率标准,向地球发射下行信号。地面台站采用无线电开环多普勒和甚长基线干涉测量技术,对其进行通信、导航和跟踪。分析处理了萤火1号的超稳定晶体振荡器频率实验测试数据,确认晶体振荡器的频率稳定度约为1×10~(12),此结果可以作为火星探测器精密测定轨的有力支撑。 相似文献
9.
10.
11.
G. Altavilla S. Marinoni E. Pancino S. Galleti S. Ragaini M. Bellazzini G. Cocozza A. Bragaglia J. M. Carrasco A. Castro L. Di Fabrizio L. Federici F. Figueras M. Gebran C. Jordi E. Masana W. Schuster G. Valentini H. Voss 《Astronomische Nachrichten》2015,336(6):515-529
The Gaia SpectroPhotometric Standard Stars (SPSS) survey started in 2006, was awarded almost 450 observing nights and accumulated almost 100000 raw data frames with both photometric and spectroscopic observations. Such large observational effort requires careful, homogeneous, and automatic data reduction and quality control procedures. In this paper, we quantitatively evaluate instrumental effects that might have a significant (i.e., ≥1 %) impact on the Gaia SPSS flux calibration. The measurements involve six different instruments, monitored over the eight years of observations dedicated to the Gaia flux standards campaigns: DOLORES@TNG in La Palma, EFOSC2@NTT and ROSS@REM in La Silla, CAFOS@2.2m in Calar Alto, BFOSC@Cassini in Loiano, and LaRuca@1.5m in San Pedro Mártir. We examine and quantitatively evaluate the following effects: CCD linearity and shutter times, calibration frames stability, lamp flexures, second order contamination, light polarization, and fringing. We present methods to correct for the relevant effects which can be applied to a wide range of observational projects at similar instruments. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
12.
Robert West Benjamin Knowles Sebastien Charnoz Matthew Hedman Alfred McEwen Carolyn Porco Henry Throop 《Planetary and Space Science》2010,58(11):1475-1488
We describe in-flight calibration of the Cassini Imaging Science Sub-system narrow- and wide-angle cameras using data from 2004 to 2009. We report on the photometric performance of the cameras including the use of polarization filters, point spread functions over a dynamic range greater than 107, gain and loss of hot pixels, changes in flat fields, and an analysis of charge transfer efficiency. Hot pixel behavior is more complicated than can be understood by a process of activation by cosmic ray damage and deactivation by annealing. Point spread function (PSF) analysis revealed a ghost feature associated with the narrow-angle camera Green filter. More generally, the observed PSFs do not fall off with distance as rapidly as expected if diffraction were the primary contributor. Stray light produces significant signal far from the center of the PSF. Our photometric analysis made use of calibrated spectra from eighteen stars and the spectral shape of the satellite Enceladus. The analysis revealed a shutter offset that differed from pre-launch calibration. It affects the shortest exposures. Star photometry results are reproducible to a few percent in most filters. No degradation in charge transfer efficiency has been detected although uncertainties are large. The results of this work have been digitally archived and incorporated into our calibration software CISSCAL available online. 相似文献
13.
We report laboratory and telescopic observations with a polarimetric spectral imager based on an acousto-optic tunable filter (AOTF) where we demonstrate simultaneous acquisition of orthogonally polarized images at a spectral resolving power on the order of 103 and at a Rayleigh criterion spatial resolution of 100 line pairs per mm. This matches the spatial resolution of most digital arrays. An AOTF is shown to be usable as a fast shutter with a contrast of over 104 on a sub-millisecond time scale while providing an high transmittance of about 75% (both polarizations summed) when illuminated by white light. The polarization contrast between the orthogonally polarized images exceeds 104 across the field of view, permitting accurate measurement of the polarization parameters of incident light. These characteristics are now being used in a program of high spatial resolution imaging in narrow spectral bands. Some peculiarities and limitations of AOTFs are indicated.This research was supported by NASA under Grant NAGW-122 and under contract with the Jet Propulsion Laboratory under NASA grant NAS 7-918.Visiting Astronomer, Mauna Kea Observatory. 相似文献
14.
对兴隆６０ｃｍ望远镜主焦ＣＣＤ系统的测光性能进行了测试和研究．测定了ＣＣＤ快门时间函数,讨论了快门延迟效应对短时间曝光观测的可能影响．通过观测大批Ｌａｎｄｏｌｔ标准星,较准确地定出了ＢＶＲＩ宽带测光的星等系统转换关系,结果表明本系统与标准ＢＶＲＩ系统很接近．对ＣＣＤ系统的天文测光精度作了仔细的检验和分析,并对ＰＳＦ拟合测光和孔径测光两种方法进行了比较 相似文献
15.
We designed a prime focus CCD photometer, Argos, optimized for high speed time-series measurements of blue variables (Nather
& Mukadam 2004) for the 2.1 m telescope at McDonald Observatory. Lack of any intervening optics between the primary mirror
and the CCD makes the instrument highly efficient. We measure an improvement in sensitivity by a factor of nine over the 3-channel
PMT photometers used on the same telescope and for the same exposure time. The CCD frame transfer operation triggered by GPS
synchronized pulses serves as an electronic shutter for the photometer. This minimizes the dead time between exposures, but
more importantly, allows a precise control of the start and duration of the exposure. We expect the uncertainty in our timing
to be less than 100μs.
Hubble Fellow 相似文献
16.
Robert M. Howie Jonathan Paxman Philip A. Bland Martin C. Towner Eleanor K. Sansom Hadrien A. R. Devillepoix 《Meteoritics & planetary science》2017,52(8):1669-1682
Long‐exposure fireball photographs have been used to systematically record meteoroid trajectories, calculate heliocentric orbits, and determine meteorite fall positions since the mid‐20th century. Periodic shuttering is used to determine meteoroid velocity, but up until this point, a separate method of precisely determining the arrival time of a meteoroid was required. We show it is possible to encode precise arrival times directly into the meteor image by driving the periodic shutter according to a particular pattern—a de Bruijn sequence—and eliminate the need for a separate subsystem to record absolute fireball timing. The Desert Fireball Network has implemented this approach using a microcontroller driven electro‐optic shutter synchronized with GNSS UTC time to create small, simple, and cost‐effective high‐precision fireball observatories with submillisecond timing accuracy. 相似文献
17.
Observational results from the supersoft X-ray detector (SD) aboard the spacecraft Shenzhou-2 are briefly described. The resultspertain to cosmic γ-ray bursts solar x-ray bursts, high-energy charged particles and soft X-ray background radiation. The detector is a proportional counter with a polypropylene thin-film window of 50 mm diameter, it operates in the energy range 0.23–3.0keV covered by six energy channels. Two grades of time resolution are used: 40 ms for recording burst events and 520 ms when there is no triggering signal resulted from a burst event. Figures 1 and 2 show the light curves and energy spectra of two cosmic γ-ray bursts (starting time 2001 Jan 17, 09:37:25.21 UT and 2001 Mar 9, 12:33:55.692 UT), and Figures 3 and 4, the results on two solar X-ray burst (2001 Apr 6, 19:14:09.11 UT, and 2001 May 20, 06:02:12.58 UT). The detector records the ambient high-energy charged particles when there is no burst event and the shutter of the window is closed. 110 data sets of high-energy charged particles along the spacecraft orbit have been collected. As examples, the variations of the particle counting rate along the orbit are shown in Figs. 6a, 6b, 8e, 8f and 7. More than 10 events of particle precipitation induced by solar proton events have also been recorded, some of which are displayed in Figs.6c–6f and 7. Some of the data of soft X-ray background radiation shown in Fig. 8 were obtained when the shutter was open, and they are important for the data processing of the burst events. 相似文献
18.
《天文和天体物理学研究(英文版)》2016,(12)
A first generation sodium Laser Guide Star Adaptive Optics System(LGS-AOS) was developed and integrated into the Lijiang 1.8 m telescope in 2013. The LGS-AOS has three sub-systems:(1) a 20 W long pulsed sodium laser,(2) a 300-millimeter-diameter laser launch telescope, and(3) a 37-element compact adaptive optics system. On 2014 January 25, we obtained high resolution images of an mV8.18 star,HIP 43963, during the first light of the LGS-AOS. In this paper, the sodium laser, the laser launch telescope,the compact adaptive optics system and the first light results will be presented. 相似文献
19.
B. L. Ellerbroek 《Journal of Astrophysics and Astronomy》2013,34(2):121-139
We provide an update on the recent development of the adaptive optics (AO) systems for the Thirty Meter Telescope (TMT) since mid-2011. The first light AO facility for TMT consists of the Narrow Field Infra-Red AO System (NFIRAOS) and the associated Laser Guide Star Facility (LGSF). This order 60 × 60 laser guide star (LGS) multi-conjugate AO (MCAO) architecture will provide uniform, diffraction-limited performance in the J, H and K bands over 17–30 arcsec diameter fields with 50 per cent sky coverage at the galactic pole, as is required to support TMT science cases. The NFIRAOS and LGSF subsystems completed successful preliminary and conceptual design reviews, respectively, in the latter part of 2011. We also report on progress in AO component prototyping, control algorithm development, and system performance analysis, and conclude with an outline of some possible future AO systems for TMT. 相似文献