相关论文: Determining the Range of an Artificial Satellite U…
Parallax is the most important astronomical method for determining the distances from the Earth to nearby stars. We present two hands-on activities that explore the concepts and practice of parallax measurement. The first activity is a…
In order to avoid collisions with space debris, the near Earth orbit must be continuously scanned by either ground- or spaced-based facilities. For the low Earth orbit, radar telescopes are the workhorse for this task, especially due to…
Parallax measurements allow distances to celestial objects to be determined. Coupled with measurement of their position on the celestial sphere, it gives a full three-dimensional picture of the location of the objects relative to the…
The Space Infrared Telescope Facility (SIRTF) will drift away from the Earth at about 0.1 AU/yr. Microlensing events will therefore have different characteristics as seen from the satellite and the Earth. From the difference, it is possible…
Refined astrometry measurements allow us to detect large-scale deviations from isotropy through real-time observations of changes in the angular separation between sources at cosmic distances. This "cosmic parallax" effect is a powerful…
We show that distances of objects at cosmological distances can be measured directly using interferometry. Our approach to interferometric parallax comes from analysis of 4-point amplitude and intensity correlations that can be generated…
In order to understand the nature of the lenses that generate microlensing events, one would like to measure their mass, distance, and velocity. Unfortunately, current microlensing experiments measure only one parameter of the events, the…
Determination of absolute parallaxes by means of a scanning astrometric satellite such as Hipparcos or Gaia relies on the short-term stability of the so-called basic angle between the two viewing directions. Uncalibrated variations of the…
Radio telescopes observe extremely faint emission from astronomical objects, ranging from compact sources to large scale structures that can be seen across the whole sky. Satellites actively transmit at radio frequencies (particularly at…
The Gaia satellite will soon probe parallax on cosmological distances. Using the covariant formalism and considering the angle between a pair of sources, we find parallax for both spacelike and timelike separation between observation…
Large constellations of artificial satellites are beginning to interfere with astronomical observing. Visual magnitude measurements of these spacecraft are useful for monitoring and characterizing their brightness. This paper describes the…
We study the apparent optical brightness of satellite streaks in ground-based observatory cameras as the orbit height is varied. This is done via simulations. Several factors are in play: the range to the satellite, satellite size and…
The impact of large-scale constellations of satellites, is a concern for ground-based astronomers. In recent years there has been a significant increase in the number of satellites in Low-Earth Orbit and this trend is set to continue. The…
I show that for a substantial fraction of planets detected in a space-based survey, it would be possible to measure the planet and host masses and distances, if the survey satellite were placed in geosynchronous orbit. Such an orbit would…
Gravitational-wave astronomy allows us to study objects and events invisible to electromagnetic waves. So far, only signals triggered by coalescing binaries have been detected. However, as the interferometers' sensitivities improve over…
Massive Compact Objects (Machos) are currently being discovered at substantially higher rates than would be expected from standard models of known stellar populations. To determine whether they are due to non-standard distri- butions of…
The apparent brightness of satellites is calculated as a function of satellite position as seen by a ground-based observer in darkness. Both direct illumination of the satellite by the Sun as well as indirect illumination due to reflection…
Space-based observatories at the second Sun-Earth Lagrange Point (L2) offer a unique opportunity to efficiently determine the orbits of distant solar system objects by taking advantage of the parallax effect that arises from nearly…
The study explored the usage of astronomical observations for the identification and tracking of artificial satellites. Spacecraft streaks on astronomical images are a growing issue for the astronomical community. The increasing number of…
In determining the distances to stars within the Milky Way galaxy, one often uses photometric or spectroscopic parallax. In these methods, the type of each individual star is determined, and the absolute magnitude of that star type is…