scholarly journals Diva - A Small Satellite for Global Astrometry and Photometry

1998 ◽  
Vol 11 (1) ◽  
pp. 583-583
Author(s):  
S. Röser ◽  
U. Bastian ◽  
K.S. de Boer ◽  
E. Høg ◽  
E. Schilbach ◽  
...  
Keyword(s):  
High Precision ◽  
Wavelength Range ◽  
Fizeau Interferometer ◽  
Proper Motions ◽  
Small Satellite ◽  
Short Overview ◽  
Photometric Observations ◽  
Photometric Measurements ◽  
First Time ◽  
Astronomy And Astrophysics

DIVA (Double Interferometer for Visual Astrometry) is a Fizeau interferometer on a small satellite. It will perform astrometric and photometric observations of at least 4 million stars. A launch in 2002 and a minimum mission length of 24 months are aimed at. A detailed description of the experiment can be obtained from the DIVA homepage at http://www.aip.de:8080/᷉dso/diva. An overview is given by Röser et al., 1997. The limiting magnitude of DIVA is about V = 15 for spectral types earlier than M0, but drops to about V = 17.5 for stars later than M5. Table 1 gives a short overview on DIVA’s performance. DIVA will carry out a skysurvey complete to V = 12.5. For the first time this survey will comprise precise photometry in at least 8 bands in the wavelength range from 400 to 1000 nm. DIVA will improve parallaxes by a factor of 3 compared to Hipparcos; proper motions by at least a factor of 2 and, in combination with the Hipparcos observations, by a factor of 10 for Hipparcos stars. At least 30 times asmany stars as Hipparcos will be observed, and doing this DIVA will fill the gap in observations between Hipparcos and GAIA. DIVA’s combined astrometric and photometric measurements of high precision will have important impacts on astronomy and astrophysics in the next decade.

scholarly journals CPC2 Reduction with Hipparcos and Proper Motions in The Southern Hemisphere

1998 ◽  
Vol 11 (1) ◽  
pp. 551-551
Author(s):  
N. Zacharias ◽  
M.I. Zacharias ◽  
C. de Vegt ◽  
C.A. Murray
Keyword(s):  
Southern Hemisphere ◽  
Systematic Errors ◽  
Reference Star ◽  
Proper Motions ◽  
Positional Accuracy ◽  
Star Catalog ◽  
Naval Observatory ◽  
Celestial Reference System ◽  
First Time ◽  
Better Than

The Second Cape Photographic Catalog (CPC2) contains 276,131 stars covering the entire Southern Hemisphere in a 4-fold overlap pattern. Its mean epoch is 1968, which makes it a key catalog for proper motions. A new reduction of the 5687 plates using on average 40 Hipparcos stars per plate has resulted in a vastly improved catalog with a positional accuracy of about 40 mas (median value) per coordinate, which comes very close to the measuring precision. In particular, for the first time systematic errors depending on magnitude and color can be solved unambiguously and have been removed from the catalog. In combination with the Tycho Catalogue (mean epoch 1991.25) and the upcoming U.S. Naval Observatory CCD Astrograph Catalog (UCAC) project proper motions better than 2 mas/yr can be obtained. This will lead to a vastly improved reference star catalog in the Southern Hemisphere for the final Astrographic Catalogue (AC) reductions, which will then provide propermotions for millions of stars when combined with new epoch data. These data then will allow an uncompromised reduction of the southern Schmidt surveys on the International Celestial Reference System (ICRS).

Research on the Key Technologies for New Large Dual-Platen High-Precision Clamping System

2010 ◽  
Vol 97-101 ◽  
pp. 64-68
Author(s):  
Jian Chen ◽  
Jin Wang ◽  
Guo Dong Lu ◽  
Zheng Qi Ling
Keyword(s):  
High Precision ◽  
Large Scale ◽  
New Technologies ◽  
Impact Factors ◽  
Adaptive Correction ◽  
Hydraulic Servo ◽  
New Type ◽  
Clamping System ◽  
Plastic Parts ◽  
First Time

High- precision and large scale are the developing trend for injection molding machine clamping system .This paper compared the characteristics of three-platen toggle and dual-platen hydraulic clamping system. The key impact factors that effecting plastic parts` precision from clamping system were discussed systematically first time. Based on these analyses, a new clamping system has been proposed and manufactured to improve the plastics parts` precision, including three new technologies: new type dual-platen structure, parallelism adaptive correction technology and numerical controlled hydraulic servo system technology. It has been applied in practical machine successfully, and experiment result proves that it is effective enough to satisfying the high-precision molding of large plastics parts.

scholarly journals InP–InxGa1−xAs core-multi-shell nanowire quantum wells with tunable emission in the 1.3–1.55 μm wavelength range

Nanoscale ◽  
2017 ◽  
Vol 9 (36) ◽  
pp. 13554-13562 ◽  
Author(s):  
H. A. Fonseka ◽  
A. S. Ameruddin ◽  
P. Caroff ◽  
D. Tedeschi ◽  
M. De Luca ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Wavelength Range ◽  
Optical Communication ◽  
Wurtzite Phase ◽  
First Time ◽  
Tunable Emission

Wurtzite phase InP–InxGa1−xAs nanowire radial quantum wells were grown for the first time, with tunable emission in the 1.3–1.55 μm optical communication wavelength range.

scholarly journals NEW RECORDS OF SUBTERRANEAN AND SPRING MOLLUSCS (GASTROPODA: HYDROBIIDAE) FROM MONTENEGRO AND ALBANIA WITH THE DESCRIPTION OF FIVE NEW SPECIES

2015 ◽  
Vol 4 ◽  
pp. 70-82
Author(s):  
Peter Glöer ◽  
Jozef Grego ◽  
Zoltán Péter Erőss ◽  
Zoltán Fehér
Keyword(s):  
New Species ◽  
New Records ◽  
Special Focus ◽  
Short Overview ◽  
First Time

A short overview of subterranean Balkan hydrobid genera, with special focus on genus Bythiospeum Bourguignat, 1892 and Iglica A.J. Wagner, 1928 is given. In addition, based on recently collected material in Montenegro (Vitoja Spring) and Albania (Krumë), five new species are described, namely: Bracenica vitojaensis n. sp., Islamia montenegrina n. sp., Lanzaia pesici n. sp., Bythiospeum szarowskae n. sp. and Pseudamnicola krumensis n. sp. The holotypes and paratypes are depicted. In addition a re-description of Bythiospeum gittenbergeri (A. & P.L. Reischütz, 2008) is given and the types of the Iglica spp. deposited in the NHMW are depicted, some of them for the first time.

Investigation of relative motion in the triple system ADS 48 on the basis of Gaia DR2 and Pulkovo 26-inch refractor observations

2021 ◽  
pp. 89-98
Author(s):  
O. V. KIYAEVA ◽  
R. YA. ZHUCHKOV ◽  
I.S. IZMAILOV
Keyword(s):  
High Precision ◽  
Relative Motion ◽  
Apparent Motion ◽  
Triple System ◽  
Radial Velocities ◽  
Proper Motions ◽  
The Family ◽  
Outer Pair ◽  
Motion Parameters ◽  
Gaia Dr2

There are high-precision positions, proper motions, parallaxes and radial velocities at the instant 2015.5 for all three components of the star ADS 48 ABF in the catalogue Gaia DR2 (2018). According to these data relative motions and the family of orbits were calculated by the Apparent Motion Parameters (AMP) method (Kiselev and Kiyaeva, 1980), and the best orbit was chosen for the inner pair AB. A perturbation with the period of 11 years was discovered according to Pulkovo observations of the outer pair. The reasons for the perturbation are discussed.

Measurement Errors in 632.8 nm High Precision Phase-Shifting Fizeau Interferometer

2010 ◽  
Vol 47 (4) ◽  
pp. 041202
Author(s):  
魏豪明 Wei Haoming ◽  
邢廷文 Xing Tingwen ◽  
李云 Li Yun ◽  
刘志祥 Liu Zhixiang
Keyword(s):  
High Precision ◽  
Measurement Errors ◽  
Phase Shifting ◽  
Fizeau Interferometer ◽  
Precision Phase

scholarly journals Astrometric Programs by the New Hamburg Plate Measuring Machine

1994 ◽  
Vol 161 ◽  
pp. 173-176
Author(s):  
Chr. de Vegt ◽  
L. Winter ◽  
N. Zacharias
Keyword(s):  
Reference Frame ◽  
Northern Hemisphere ◽  
High Accuracy ◽  
Proper Motions ◽  
Sky Surveys ◽  
Unique Data ◽  
Large Sets ◽  
Measuring Machine ◽  
First Time

With the new Hamburg astrometric measuring machine, large sets of plates can be digitized very quickly with submicrometer accuracy. In particular about 2000 plates of the AGK2-catalog, mean epoch 1930, can be remeasured now for the first time to their limiting magnitude, about B = 11. The new AGK2-data therefore will cover practically the whole AC-catalog and TYCHO-stars in the northern hemisphere. All plates will be reduced using the HIPPARCOS results as the reference frame when available in 1996. The new AGK2-data will provide a unique data base for the determination of high accuracy proper motions (about 2 mas/yr) of all TYCHO stars in the northern hemisphere. Furthermore, for the first time a dense reference frame for a final reduction of the Astrographic Catalog (AC) and the large deep sky surveys will be generated by this catalog. The inferior situation in the southern hemisphere will be addressed briefly.

scholarly journals Proxima’s orbit around α Centauri

2017 ◽  
Vol 598 ◽  
pp. L7 ◽  
Author(s):  
P. Kervella ◽  
F. Thévenin ◽  
C. Lovis
Keyword(s):  
Radial Velocity ◽  
High Precision ◽  
Orbital Period ◽  
Triple System ◽  
Orbital Motion ◽  
The Sun ◽  
Proper Motions ◽  
Velocity Measurements ◽  
Degree Of Confidence ◽  
High Degree

Proxima and α Centauri AB have almost identical distances and proper motions with respect to the Sun. Although the probability of such similar parameters is, in principle, very low, the question as to whether they actually form a single gravitationally bound triple system has been open since the discovery of Proxima one century ago. Owing to HARPS high-precision absolute radial velocity measurements and the recent revision of the parameters of the α Cen pair, we show that Proxima and α Cen are gravitationally bound with a high degree of confidence. The orbital period of Proxima is ≈ 550 000 yr. With an eccentricity of 0.50+0.08-0.09, Proxima comes within 4.3+1.1-0.9 kau of α Cen at periastron, and is currently close to apastron (13.0+0.3-0.1 kau). This orbital motion may have influenced the formation or evolution of the recently discovered planet orbiting Proxima, as well as circumbinary planet formation around α Cen.

Temperature and composition measurements from the l.r.i.r. and l.i.m.s. experiments on Nimbus 6 and 7

1980 ◽  
Vol 296 (1418) ◽  
pp. 205-218 ◽  
Keyword(s):  
High Precision ◽  
Trace Gas ◽  
Transport Problems ◽  
Rocket Measurements ◽  
Inversion Techniques ◽  
And Inversion ◽  
First Time ◽  
Good Agreement ◽  
Composition Measurements

The limb radiance inversion radiometer (l.r.i.r.) on Nimbus 6 was the first orbiting infrared limb scanner. It had four channels with which to determine temperature, Oz and H aO in the stratosphere and low mesosphere. The limb infrared monitor of the stratosphere (l.i.m.s.) is a similar six-channel instrument launched on Nimbus 7 in October 1978 to measure temperature, O 3 , H 2 O , NO 2 and HNO 3 . The instrumentation and inversion techniques are briefly described. In this method, the outwelling radiance in the 15 pm bands of CO 2 is inverted to yield temperatures as a function of pressure; the temperature is then used w ith the radiance emitted by a trace gas to determine its concentration. L.r.i.r. temperature and ozone results show high precision and good agreement with rocket measurements from the tropopause into the mesosphere. Preliminary l.i.m.s. results show that temperatures may be retrieved into the troposphere, and the capability to determine constituent concentrations in the part / 10 9 range from a satellite for the first time. The application of such data for photochemical dynamical and transport problems is discussed.

Internal kinematics of multiple stellar populations in globular clusters

2019 ◽  
Vol 14 (S351) ◽  
pp. 324-328
Author(s):  
Mattia Libralato
Keyword(s):  
High Precision ◽  
Globular Clusters ◽  
Hubble Space Telescope ◽  
Stellar Populations ◽  
Stellar Systems ◽  
Proper Motions ◽  
Space Telescope ◽  
Formation And Evolution ◽  
Galactic Globular Clusters ◽  
Shed Light

AbstractSpectroscopy and photometry have revealed existence, complexity and properties of the multiple stellar populations (mPOPs) hosted in Galactic globular clusters. However, the conundrum of the formation and evolution of mPOPs is far from being completely exploited: the available pieces of information seem not enough to shed light on these topics. Astrometry, and in particular high-precision proper motions, can provide us the sought-after answers about how mPOPs formed and have evolved in these ancient stellar systems. In the following, I present a brief overview of the observational results on the internal kinematics of the mPOPs in some GCs thanks to Hubble Space Telescope high-precision proper motions.

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