共查询到20条相似文献,搜索用时 562 毫秒
1.
A collaborative programme searching for mmag pulsations in chemically peculiar stars in the northern hemisphere was initiated
in 1997 between Nainital, India, and Cape Town, South Africa. It was therefore named as theNainital-Cape Survey programme. The detection limits imposed by the observing conditions (including atmospheric noise and telescope size) at both
Manora Peak and Devasthal sites are described. The scintillation noise on the best photometric nights is≈ 0.1 to 0.2 mmag for these sites. Both places allow one to detect few mmag variation in bright stars(B ≤ 12 mag), and are therefore particularly well-suited for carrying out the proposed survey work. The main characteristics of
the three-channel photometer developed at ARIES for carrying out the observations are also presented. This excellent instrument
has been used extensively since 1999 at the f/13 Cassegrain focus of ARIES’ 104 cm telescope. In particular, it allowed the
survey to result in the discovery of δ Scuti like pulsations in four Am stars, in one rapidly oscillating Ap star, and in
a number of probable variables so far. The future prospects are then presented, which regard the acquisition of a high speed
time series CCD photometer, a project to build a 3-metre class telescope at Devasthal, and collaborative observations with
Indian and foreign astronomical sites. 相似文献
2.
暗弱天然卫星与主带小行星相比,具有亮度低、速度变化快的特点.在观测这类天体时,不能简单地延长曝光时间来提高其信噪比.尝试观测多幅短曝光的CCD (chargecoupled device)图像,采用移位堆叠(shift-and-add)方法,希望提高目标成像的信噪比,获得暗弱天然卫星的精确测量结果.使用2018年4月9—12日夜间,中国科学院云南天文台1 m望远镜(1 m望远镜)拍摄的木星5颗暗卫星的229幅CCD图像,实施了移位堆叠试验.为了验证结果的正确性,与相近日期中国科学院云南天文台2.4 m望远镜(2.4 m望远镜)观测的相同木卫图像的测量结果进行了比较和分析.位置归算采用了JPL (Jet Propulsion Laboratory)历表.结果表明,对CCD图像使用移位堆叠方法,通过叠加约10幅曝光时间100 s的图像, 1 m望远镜能观测暗至19等星的不规则天然卫星,而且测量的准确度与2.4 m望远镜的测量结果有良好的一致性. 相似文献
3.
Toshifumi Yanagisawa Yasushi Muraki Yutaka Matsubara Fumio Abe Kimiaki Masuda Sachiyo Noda Takahiro Sumi Yuji Kato Mitsuaki Fujimoto Shuji Sato Ian Bond Nicholas Rattenbury Philip Yock Pam Kilmartin John Hearnshaw Micheal Reid Denis Sullivan Brian Carter Richard Dodd Garry Nankivell Noiman Rumsey Morihiro Honda Maki Sekiguchi Masanori Yoshizawa Takashi Nakamura Humitaka Sato Seiji Kabe Makoto Kobayashi Yoshiyuki Watase Jun Jugaku Toshiharu Saito Barbel Koribalsky 《Experimental Astronomy》2000,10(4):519-535
We have constructed a large, mosaic CCD camera called MOA-cam2 which has 4096 × 6144-pixelsto search for gravitational microlensing events. MOA-cam2 has three4096 × 2048-pixel SITe CCD chips, which have a very high quantum efficiency (nearly 80% in the wave region 500 to 800 nm),and three buttable sides. We have placed the threechips side by side with 100 m dead space. MOA-cam2 has been installed on the 61 cm Boller and Chivens telescope of the MOA collaboration at the Mt. John University Observatory (MJUO) in NewZealand since July 1998. The field coverage is 0.92° × 1.38° per exposure. The technical details of MOA-cam2 and the first images obtained with the Boller and Chivens telescope are presented. MOA-cam2 introduces a second phase of research on gravitational microlensing by the MOA collaboration. 相似文献
4.
OPTIMA is a small, versatile high-speed photometer which is primarily intended for time resolved observations of young high energy pulsars at optical wavelengths. The detector system consists of eight fiber fed photon counters based on avalanche photodiodes, a GPS timing receiver, an integrating CCD camera to ensure the correct pointing of the telescope and a computerized control unit. Since January 1999 OPTIMA proves its scientific potential by measuring a very detailed light-curve of the Crab Pulsar as well as by observing cataclysmic variable stars on very short timescales. In this article we describe the design of the detector system focussing on the photon counting units and the software control which correlates the detected photons with the GPS timing signal. 相似文献
5.
P. B. Van Der Wal B. G. Anandarao D. Rouan P. Léna M. De Muizon J. Wijnbergen 《Astrophysics and Space Science》1985,117(2):209-216
We describe here a far-infrared photometer capable of detecting simultaneously in three bands in the region 20–120 microns, each band having an array of 3 or 4 photoconductive detectors. We present and discuss its laboratory performance and the results obtained on the planet Venus during an air-borne observational programme using a 32.5 cm telescope. We also present the atmospheric spectra obtained by a Michelson interferometer aboard the aircraft. 相似文献
6.
OPTIMA is a small, versatile high-speed photometer which is primarily intended for time resolved observations of young high
energy pulsars at optical wavelengths. The detector system consists of eight fiber fed photon counters based on avalanche
photodiodes, a GPS timing receiver, an integrating CCD camera to ensure the correct pointing of the telescope and a computerized
control unit. Since January 1999 OPTIMA proves its scientific potential by measuring a very detailed light-curve of the Crab
Pulsar as well as by observing cataclysmic variable stars on very short timescales. In this article we describe the design
of the detector system focussing on the photon counting units and the software control which correlates the detected photons
with the GPS timing signal.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
7.
M. G. Revnivtsev R. A. Burenin A. Yu. Tkachenko I. M. Khamitov T. Ak A. Merloni M. N. Pavlinsky R. A. Sunyaev 《Astronomy Letters》2012,38(4):238-248
We present the results of our studies of the aperiodic optical flux variability for SS Cyg, an accreting binary systemwith
a white dwarf. The main set of observational data presented here was obtained with the ANDOR/iXon DU-888 photometer mounted
on the RTT-150 telescope, which allowed a record (for CCD photometers) time resolution up to 8 ms to be achieved. The power
spectra of the source’s flux variability have revealed that the aperiodic variability contains information about the inner
boundary of the optically thick flow in the binary system. We show that the inner boundary of the optically thick accretion
disk comes close to the white dwarf surface at the maximum of the source’s bolometric light curve, i.e., at the peak of the
instantaneous accretion rate onto the white dwarf, while the optically thick accretion disk is truncated at distances 8.5
× 109 cm ∼10R
WD in the low state. We suggest that the location of the inner boundary of the accretion disk in the binary can be traced by
studying the parameters of the power spectra for accreting white dwarfs. In particular, this allows the mass of the accreting
object to be estimated. 相似文献
8.
J. W. Campbell 《Astrophysics and Space Science》1971,11(3):417-422
A stellar photometer utilizing a Cassegrain telescope optical system was flown in a Skylark rocket. The photometer scanned the night sky using the precessional and roll motions of the rocket and obtained observations of some ninety-two stars at a wavelength of 1450 Å. 相似文献
9.
We describe a new BVRI multicolor CCD photometric system situated at the prime focus of the 85-cm telescope at the Xinglong Station of NAOC. Atmospheric extinction effects, photometric accuracy and color calibration dependence of the system are investigated. Additional attention was paid to giving observers guidance in estimating throughput, detection limit, signal-to-noise ratio and exposure time. 相似文献
10.
G. A. Chuntonov 《Astrophysical Bulletin》2013,68(4):461-464
We search for the variable component of themagnetic field in γ Equ by studying four Nd III lines with the Main Stellar Spectrograph of the 6-m BTA telescope of the Special Astrophysical Observatory via accumulation and cyclic transfer of the electronic image of the Zeeman spectrum on the CCD. The single exposure time was set equal to 1/8 of the spectral variability period. We detected no variable component in the magnetic field of γ Equ with a period of 12.1 min in the November 5/6, 2003 observations. 相似文献
11.
《Chinese Astronomy and Astrophysics》1982,6(2):153-157
We report on the design and construction of a l–3μ infrared photometer. We use a pre-focus rotating chopper to effect modulation and, unlike some previous designs, we use the chopper to feed in the sky background only, and use a fixed mirror to feed in the star signal. In this way, excess demand on the precision setting of the rotating chopper Is avoided. Test observations on a 1-m telescope show that our photometer is capable of observing all the IRC sources with an accuracy better than O.lmag at a time constant of 2 minutes. 相似文献
12.
现有标准设计的反光望远镜在拍摄CCD平场时,绝大多数都受残留散射光的影响.但是赤道式与地平式反光镜所受影响是不同的.在赤道式上做时间序列较差测光时,只要待测星永远位于CCD的固定像元上,不太准确的CCD平场也能得到高精度的测光结果.当需要0.1%~0.3%精度的平场时,则可以采用夜天平场.地平式的特点是,它的CCD相机必须置于旋转器上,在跟踪天体时不停地旋转,以抵消地球自转的影响.上述用于赤道式的方法失效,因此,在CCD平场时,消除散射光的影响比赤道式更为重要.一个典型的地平式反光镜的例子是NAOC兴隆天文台的EOS 1米镜.虽然该台已附加了防散射光的装置,但是对所有B、V、R、I滤光片,在不同旋转器位置拍摄的CCD平场,仍然有2%~3%的差别(主要是梯度).该文给出了改进的建议,必须满足下面两个条件:Cij=C(r);旋转器的中心与反光镜的光学中心重合.此问题的解决对所有地平式反光望远镜都有普遍意义. 相似文献
13.
V. L. Karbovs’ky P. F. Lazorenko V. N. Andruk V. V. Kleshchenok M. O. Litvin K. O. Bogatyrev E. V. Denisyuk 《Kinematics and Physics of Celestial Bodies》2011,27(4):204-210
Specifications of a new Apogee Alta U47 CCD camera mounted at the Kyiv meridian axial circle (MAC) are presented. The camera
is based on the 1024 × 1024 pxl e2v CCD47-10 with pixel sizes of 13 × 13 μm. Observations are carried out in the scan-drift
mode with an effective exposure time of 77 s for equatorial stars. The MAC photometric system answers the standard Johnson
V band, the MAC limiting magnitude V is 17
m
. The test MAC observations of 2009 give positional accuracy and V magnitude errors equal to approximately 0.1″ and 0.09
m
, respectively, for Tycho-2 stars. The telescope is used for observations of equatorial stars with the purpose of detecting
their positions, proper motion, and brightness. 相似文献
14.
R. A. Burenin M. G. Revnivtsev I. M. Khamitov I. F. Bikmaev A. S. Nosov M. N. Pavlinsky R. A. Sunyaev 《Astronomy Letters》2011,37(2):100-112
We study the variability of the optical flux from the peculiar Galactic source SS 433 based on observations with the Russian-Turkish
1.5-m telescope. We describe in detail the technique of highquality photometric measurements with a time resolution of 0.3–1
s using an ordinary CCD. Through test observations of nonvariable stars, we show that atmospheric turbulence introduces no
significant distortions into the light curves. Therefore, such data are well suited for studying the aperiodic variability of various objects. 相似文献
15.
D. P. Sharma B. V. Nagaraja J. C. Bhattacharyya S. Mohin A. V. Raveendran 《Astrophysics and Space Science》1983,95(1):65-77
We have monitored the X-ray source X-Per (4U 0352+30) on 31 August, 1979 through aU filter for about 1.5 hr using 102-cm telescope of Kavalur observatory. During this period intensity of X-Per fluctuated for some time, on time scales of few minutes but recovered in the end. It was again monitored from 27 December, 1979 to January 1980 through a standardU, B, V photometer attached to a 34-cm telescope. In this paper we present the data on the fast flickerings observed on 31 August, 1979 and on the long term monitoring from December 1979 to January 1980. 相似文献
16.
17.
T. Sako T. Sekiguchi M. Sasaki K. Okajima F. Abe I. A. Bond J. B. Hearnshaw Y. Itow K. Kamiya P. M. Kilmartin K. Masuda Y. Matsubara Y. Muraki N. J. Rattenbury D. J. Sullivan T. Sumi P. Tristram T. Yanagisawa P. C. M. Yock 《Experimental Astronomy》2008,22(1-2):51-66
We have developed a wide-field mosaic CCD camera, MOA-cam3, mounted at the prime focus of the Microlensing Observations in Astrophysics (MOA) 1.8-m telescope. The camera consists of ten E2V CCD4482 chips, each having 2k×4k pixels, and covers a 2.2 deg2 field of view with a single exposure. The optical system is well optimized to realize uniform image quality over this wide field. The chips are constantly cooled by a cryocooler at ??80° C, at which temperature dark current noise is negligible for a typical 1–3 min exposure. The CCD output charge is converted to a 16-bit digital signal by the GenIII system (Astronomical Research Cameras Inc.) and readout is within 25 s. Readout noise of 2–3 ADU (rms) is also negligible. We prepared a wide-band red filter for an effective microlensing survey and also Bessell V, I filters for standard astronomical studies. Microlensing studies have entered into a new era, which requires more statistics, and more rapid alerts to catch exotic light curves. Our new system is a powerful tool to realize both these requirements. 相似文献
18.
L. M. Freyhammer M. I. Andersen T. Arentoft C. Sterken P. Nørregaard 《Experimental Astronomy》2001,12(3):147-162
Multi-channel CCD read-out, which is an option offered at most optical observatories, can significantly reduce the time spent
on reading the detector. The penalty of using this option is the so-called amplifier cross-talk, which causes contamination
across the output amplifiers, typically at the level of 1:10 000.This can be a serious problem for applications where high
precision and/or high contrast is of importance. We represent an analysis of amplifier cross-talk for two instruments – FORS1
at the ESO VLT telescope Antu (Paranal) and DFOSC at the Danish 1.54 m telescope (La Silla) – and present a post-processing
method for removing the imprint of cross-talk. It is found that cross-talk may significantly contaminate high-precision photometry
in crowded fields, but it can be effectively eliminated during data reduction.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
19.
B. N. Ashoka Kumar V. C. Babu S. Seetha V. Girish S. K. Gupta Ram Sagar S. Joshi P. Narang 《Journal of Astrophysics and Astronomy》2001,22(1):131-144
The design and performance of a portable three channel photometer installed at the Uttar Pradesh State Observatory (UPSO),
Naini Tal is described. The photometer is modular and the whole unit can be disassembled as individual channels such that
the system can also be used as a single channel or two channel photometer. The system also has provision to monitor a guide
star. The instrument was put into operation since November 1999 on the 1m Sampurnanand telescope at UPSO, Naini Tal. Since
then, it is used extensively for the ‘Survey of rapidly oscillating Ap (roAp) stars in the northern sky’ from UPSO. Observational
results using this new photometer in its initial phase of operation are discussed. The advantage of having continuous sky
measurement is demonstrated. 相似文献