scholarly journals Astrometry and Photometry of 400 Million Stars Brighter than 18 Mag

1993 ◽  
Vol 156 ◽  
pp. 37-45
Author(s):  
E. Høg
Keyword(s):  
Proper Motions ◽  
Satellite Mission ◽  
Beam Combiner ◽  
Expected Performance ◽  
Ccd Detectors

A satellite mission for accurate astrometry and multi-colour photometry is discussed, similar in principle to the ESA Hipparcos mission and here called theRoemer mission.The limiting magnitude will be aboutV= 18 mag while 13 mag is the limit of the present Hipparcos mission. Luminosities of stars up to 2 kpc away can be obtained, corresponding to a volume 10000 times larger than with Hipparcos. A mission of 5 years will provide an accuracy of 0.1 milli-arcsec at 12th magnitude for positions and parallaxes and 0.05 milli-arcsec for annual proper motions. This is achieved by a satellite using a mosaic of CCD detectors in the focal planes of two beam-combiner telescopes of 0.29 m aperture. The instrument is described and the expected performance with an input catalog of 400 million program stars is given.

scholarly journals Development of Embedded Boot Software for a Satellite Instrument Control Unit: Lessons Learned

2019 ◽  
Vol 2019 ◽  
pp. 1-8
Author(s):  
Jesús Fernández-Conde ◽  
Jaime Gómez-Saez-de-Tejada ◽  
David Pérez-Lizán ◽  
Rafael Toledo-Moreo
Keyword(s):  
Real Time ◽  
European Space Agency ◽  
Control Unit ◽  
Lessons Learned ◽  
System Failure ◽  
Application Software ◽  
Satellite Mission ◽  
Space Agency ◽  
Expected Performance ◽  
Instrument Control

A satellite spacecraft is generally composed of a central Control and Data Management Unit (CDMU) and several instruments, each one locally controlled by its Instrument Control Unit (ICU). Inside each ICU, the embedded boot software (BSW) is the very first piece of software executed after power-up or reset. The ICU BSW is a nonpatchable, stand-alone, real-time software package that initializes the ICU HW, performs self-tests, and waits for CDMU commands to maintain on-board memory and ultimately start a patchable application software (ASW), which is responsible for execution of the nominal tasks assigned to the ICU (control of the satellite instrument being the most important one). The BSW is a relatively small but critical software item, since an unexpected behaviour can cause or contribute to a system failure resulting in fatal consequences such as the satellite mission loss. The development of this kind of embedded software is special in many senses, primarily due to its criticality, real-time expected performance, and the constrained size of program and data memories. This paper presents the lessons learned in the development and HW/SW integration phases of a satellite ICU BSW designed for a European Space Agency mission.

scholarly journals The Gaia mission: science, organization and present status

2007 ◽  
Vol 3 (S248) ◽  
pp. 217-223 ◽  
Author(s):  
L. Lindegren ◽  
C. Babusiaux ◽  
C. Bailer-Jones ◽  
U. Bastian ◽  
A. G. A. Brown ◽  
...  
Keyword(s):  
Proper Motions ◽  
Velocity Measurements ◽  
Expected Performance ◽  
Wide Range ◽  
Operational Lifetime ◽  
Optical Reference ◽  
Spectrophotometric Data ◽  
Space Astrometry ◽  
Technical Features ◽  
Astrometric Data

AbstractThe ESA space astrometry mission Gaia will measure the positions, parallaxes and proper motions of the 1 billion brightest stars on the sky. Expected accuracies are in the 7–25 μas range down to 15 mag and sub-mas accuracies at the faint limit (20 mag). The astrometric data are complemented by low-resolution spectrophotometric data in the 330–1000 nm wavelength range and, for the brighter stars, radial velocity measurements. The scientific case covers an extremely wide range of topics in galactic and stellar astrophysics, solar system and exoplanet science, as well as the establishment of a very accurate, dense and faint optical reference frame. With a planned launch around 2012 and an (extended) operational lifetime of 6 years, final results are expected around 2021. We give a brief overview of the science goals of Gaia, the overall project organisation, expected performance, and some key technical features and challenges.

scholarly journals Infrared space astrometry project JASMINE

2007 ◽  
Vol 3 (S248) ◽  
pp. 248-251
Author(s):  
N. Gouda ◽  
Y. Kobayashi ◽  
Y. Yamada ◽  
T. Yano ◽  
Keyword(s):  
Milky Way ◽  
Development Phase ◽  
Preliminary Design ◽  
Proper Motions ◽  
Galactic Bulge ◽  
Satellite Mission ◽  
Technical Issues ◽  
Space Astrometry ◽  
Scientific Results ◽  
K Band

AbstractA Japanese plan of an infrared (z-band:0.9 μas or k-band:2.2 μas) space astrometry (JASMINE-project) is introduced. JASMINE (Japan Astrometry Satellite Mission for INfrared Exploration) will measure distances and tangential motions of stars in the bulge of the Milky Way. It will measure parallaxes, positions with an accuracy of 10 μas and proper motions with an accuracy of 10 μas/year for stars brighter than z=14 mag or k=11 mag. JASMINE will observe about ten million stars belonging to the bulge component of our Galaxy. With a completely new “map” of the Galactic bulge, it is expected that many new exciting scientific results will be obtained in various fields of astronomy. Presently, JASMINE is in a development phase, with a targeted launch date around 2016. Science targets, preliminary design of instruments, observing strategy, critical technical issues in JASMINE and also Nano-JASMINE project are described in this paper.

scholarly journals The Airborne Demonstrator for the Direct-Detection Doppler Wind Lidar ALADIN on ADM-Aeolus. Part II: Simulations and Rayleigh Receiver Radiometric Performance

2009 ◽  
Vol 26 (12) ◽  
pp. 2516-2530 ◽  
Author(s):  
Ulrike Paffrath ◽  
Christian Lemmerz ◽  
Oliver Reitebuch ◽  
Benjamin Witschas ◽  
Ines Nikolaus ◽  
...  
Keyword(s):  
Direct Detection ◽  
European Space Agency ◽  
Satellite System ◽  
Satellite Mission ◽  
Backscatter Signal ◽  
Space Agency ◽  
Expected Performance ◽  
Wind Lidar ◽  
Doppler Wind Lidar ◽  
Signal Intensities

Abstract In the frame of the Atmospheric Dynamics Mission Aeolus (ADM-Aeolus) satellite mission by the European Space Agency (ESA), a prototype of a direct-detection Doppler wind lidar was developed to measure wind from ground and aircraft at 355 nm. Wind is measured from aerosol backscatter signal with a Fizeau interferometer and from molecular backscatter signal with a Fabry–Perot interferometer. The aim of this study is to validate the satellite instrument before launch, improve the retrieval algorithms, and consolidate the expected performance. The detected backscatter signal intensities determine the instrument wind measurement performance among other factors, such as accuracy of the calibration and stability of the optical alignment. Results of measurements and simulations for a ground-based instrument are compared, analyzed, and discussed. The simulated atmospheric aerosol models were validated by use of an additional backscatter lidar. The measured Rayleigh backscatter signals of the wind lidar prototype up to an altitude of 17 km are compared to simulations and show a good agreement by a factor better than 2, including the analyses of different error sources. First analyses of the signal at the Mie receiver from high cirrus clouds are presented. In addition, the simulations of the Rayleigh signal intensities of the Atmospheric Laser Doppler Instrument (ALADIN) Airborne Demonstrator (A2D) instrument on ground and aircraft were compared to simulations of the satellite system. The satellite signal intensities above 11.5 km are larger than those from the A2D ground-based instrument and always smaller than those from the aircraft for all altitudes.

scholarly journals JASMINE: constructor of the dynamical structure of the Galactic bulge

2007 ◽  
Vol 3 (S245) ◽  
pp. 355-358
Author(s):  
N. Gouda ◽  
Y. Kobayashi ◽  
Y. Yamada ◽  
T. Yano ◽  
T. Tsujimoto ◽  
...  
Keyword(s):  
High Accuracy ◽  
Dynamical Structure ◽  
Preliminary Design ◽  
Proper Motions ◽  
Galactic Bulge ◽  
Satellite Mission ◽  
Central Wavelength ◽  
Distance Data ◽  
Space Astrometry ◽  
Scientific Results

AbstractWe introduce a Japanese space astrometry project which is called JASMINE. JASMINE (Japan Astrometry Satellite Mission for INfrared Exploration) will measure distances and tangential motions of stars in the Galactic bulge with yet unprecedented precision. JASMINE will operate in z-band whose central wavelength is 0.9 micron. It will measure parallaxes, positions with accuracy of about 10 micro-arcsec and proper motions with accuracy of about 10 micro- arcsec/year for the stars brighter than z=14 mag. The number of stars observed by JASMINE with high accuracy of parallaxes in the Galactic bulge is much larger than that observed in other space astrometry projects operating in optical bands. With the completely new “map of the Galactic bulge” including motions of bulge stars, we expect that many new exciting scientific results will be obtained in studies of the Galactic bulge. One of them is the construction of the dynamical structure of the Galactic bulge. Kinematics and distance data given by JASMINE are the closest approach to a view of the exact dynamical structure of the Galactic bulge.Presently, JASMINE is in a development phase, with a target launch date around 2016. We comment on the outline of JASMINE mission, scientific targets and a preliminary design of JASMINE in this paper.

scholarly journals Roll Calibration for CryoSat-2: A Comprehensive Approach

2021 ◽  
Vol 13 (2) ◽  
pp. 302
Author(s):  
Albert Garcia-Mondéjar ◽  
Michele Scagliola ◽  
Noel Gourmelen ◽  
Jerome Bouffard ◽  
Mònica Roca
Keyword(s):  
Pulse Repetition Frequency ◽  
Sufficient Accuracy ◽  
Comprehensive Approach ◽  
Accurate Information ◽  
Radar Altimeter ◽  
Angle Of Arrival ◽  
Satellite Mission ◽  
External Calibration ◽  
Expected Performance ◽  
High Pulse

CryoSat-2 is the first satellite mission carrying a high pulse repetition frequency radar altimeter with interferometric capability on board. Across track interferometry allows the angle to the point of closest approach to be determined by combining echoes received by two antennas and knowledge of their orientation. Accurate information of the platform mispointing angles, in particular of the roll, is crucial to determine the angle of arrival in the across-track direction with sufficient accuracy. As a consequence, different methods were designed in the CryoSat-2 calibration plan in order to estimate interferometer performance along with the mission and to assess the roll’s contribution to the accuracy of the angle of arrival. In this paper, we present the comprehensive approach used in the CryoSat-2 Mission to calibrate the roll mispointing angle, combining analysis from external calibration of both man-made targets, i.e., transponder and natural targets. The roll calibration approach for CryoSat-2 is proven to guarantee that the interferometric measurements are exceeding the expected performance.

scholarly journals From Milliarcsecond Proper Motions to the Discovery of Dark Matter: Some Winning Cards still in the hands of Photographic Astronomy

1995 ◽  
Vol 148 ◽  
pp. 90-95
Author(s):  
J. Guibert ◽  
J. Souchay
Keyword(s):  
Dark Matter ◽  
Proper Motion ◽  
Large Field ◽  
Proper Motions ◽  
Ccd Cameras ◽  
The Subject ◽  
Motion Studies ◽  
Ccd Detectors

AbstractThe large field of Schmidt plates allows monitoring of hundreds of thousands or even millions of stars, either for magnitude variations or for proper motions. CCD cameras benefit from the sensitivity, linearity, and easy interface to computers of detectors of increasing dimensions. However, especially for proper motion studies, there is no substitute to plates of first or intermediate epochs. In addition, the photographic plates, with their large sky coverage free of gaps, are irreplaceable for the accurate astrometry of optical counterparts of sources detected at other wavelengths.We first introduce the subject by mentioning a few problems concerning the replacement of Schmidt plates by CCD detectors. After a brief survey of astronomical applications requiring accurate astrometry or massive processing in large fields, we develop in more detail the results obtained in proper motion studies by several groups using the MAMA system (Berger et al. 1991). The last part of this paper is devoted to the studies of stellar variability and to the EROS and DUO microlensing programmes. Our conclusion (not a surprise, we think), is that Schmidt telescopes with photographic facilities should remain available to the general astronomical community for at least a decade and probably more.

scholarly journals Tycho Astrometry from 30 Months of Satellite Mission

1995 ◽  
Vol 166 ◽  
pp. 61-68
Author(s):  
E. Høg
Keyword(s):  
Data Processing ◽  
Systematic Errors ◽  
Proper Motions ◽  
Satellite Mission ◽  
Satisfactory Accuracy ◽  
Transit Times ◽  
Hipparcos Catalogue ◽  
Spectral Channels ◽  
Astrometric Data

The Hipparcos satellite's star mapper gives photon counts in two spectral channels simultaneously, close to Johnson B and V. The transit times and the signal amplitudes for each star across two groups of four slits are derived and used for astrometry and photometry, respectively, and this constitutes the Tycho project. The present paper describes results of Tycho astrometric data processing, leading from the transit times to the astrometric parameters of the Tycho stars.Some 30 months of Tycho observations, i.e. about 80 percent of the Hipparcos-Tycho mission, have been used to produce a working catalogue of Tycho positions, proper motions and parallaxes of a million stars. The external errors of this preliminary catalogue have been determined by comparison of 98 000 stars common with a preliminary, but much more accurate Hipparcos catalogue. External systematic errors of positions and annual proper motions are less than 0.5 milliarcsecond (mas) and the accidental errors per star are about 30 mas rms at V = 10.5 mag, the median magnitude of the catalogue. It is concluded that a satisfactory accuracy has been achieved.

scholarly journals A CCD Modulation Detector for a Second Hipparcos Mission

1993 ◽  
Vol 156 ◽  
pp. 31-36 ◽  
Author(s):  
E. Høg ◽  
L. Lindegren
Keyword(s):  
Field Of View ◽  
Proper Motions ◽  
Tube System ◽  
Aperture Diameter ◽  
Modulation Period ◽  
Beam Combiner

A CCD modulation detector for a possible Hipparcos-2 mission is described. It is at least 1000 times more light efficient than the image dissector tube system used in the current Hipparcos mission. A beam combiner telescope with 29 cm aperture diameter could measure all 15 million stars brighter than 14th magnitude, providing accurate multi-colour photometry in addition to the astrometric parameters. Using two telescopes with different basic angles will further improve the rigidity of the resulting system of positions and proper motions. An accuracy of 0.5 milli-arcsec up to 10th magnitude is expected for a 2.5 year mission. The modulating grid is imaged on a CCD performing a ‘cophased integration’ of nine separate images of the whole field of view, each image representing a different part of the modulation period.

scholarly journals Proper motions of the satellites of M31

2019 ◽  
Vol 488 (3) ◽  
pp. 3231-3237 ◽  
Author(s):  
Ben Hodkinson ◽  
Jakub Scholtz
Keyword(s):  
Line Of Sight ◽  
Current Debate ◽  
Proper Motions ◽  
Satellite Mission ◽  
Formation History ◽  
History Of ◽  
Transient Feature ◽  
Satellite Galaxies

Abstract We predict the range of proper motions of 19 satellite galaxies of M31 that would rotationally stabilize the M31 plane of satellites consisting of 15–20 members as identified by Ibata et al. Our prediction is based purely on the current positions and line-of-sight velocities of these satellites and the assumption that the plane is not a transient feature. These predictions are therefore independent of the current debate about the formation history of this plane. We further comment on the feasibility of measuring these proper motions with future observations by the THEIA satellite mission as well as the currently planned observations by HST and JWST.

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