Astrometry





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Astrometry

The latest articles related to Astrometry

Extrasolar X-ray source astrometry – Stellar parallax

On an interstellar scale, parallax created by the different orbital positions of the Earth causes nearby stars to appear to move relative to more distant stars. By observing parallax, measuring angles and using geometry, one can determine the distance to various objects. When the object in question is a star, the effect is known as [...]

Extrasolar X-ray source astrometry – Astrometry for balloons

Balloons have also been used to pinpoint X-ray source positions, e.g., Coma Berenices X-1. To observe weak X-ray sources at photon energies between 20 and 100 keV near the galactic center, a balloon flight was conducted on February 29, 1968, from Mildura, Australia. Lupus XR-1, Norma XR-2, Scorpius X-2, Scorpius XR-3, and Scorpius XR-4 could [...]

Naval Observatory Vector Astrometry Subroutines – Structure

Astrometry

The NOVAS library provides three levels of subroutines (functions): basic, utility, and supervisory. Basic-level subroutines supply the values of fundamental variables, such as the nutation angles and the heliocentric positions of solar system bodies for specific epoches. Utility-level subroutines perform transformations, such as those caused by precession, nutation and aberration. Supervisory-level subroutines serve as interfaces [...]

Extrasolar X-ray source astrometry – Visibly dark X-ray source

Astrometry

Of the first X-ray sources discovered in each constellation (126 for 89 areas), some 63% are visibly dark. These visually dark X-ray sources can be radiative cosmic dust, hydrogen gas such as an H II region (e.g. the Orion Nebula), an H I region of hydrogen, a molecular cloud, or a coronal-type gas cloud. Pinpoint [...]

Extrasolar X-ray source astrometry – Norma X-1

Astrometry

Norma XR-1 was discovered at RA Dec by an Aerobee 150 rocket flight on April 25, 1965. It may be the same source as Lockheed 1. Its visual counterpart is V801 Ara. It is a recurrent transient, located at 2S 1636-536, and designated X336-1. Although Nor X-1 has also been designated 2S 1624-490, 4U 1626-49 [...]

Extrasolar X-ray source astrometry – Sounding rocket astrometry

Astrometry

In the beginning of X-ray astronomy, the first celestial object discovered to emit X-rays was the Sun (see solar X-ray astronomy). These X-rays were detected by sounding rocket. Several different types have been used to carry X-ray detectors above the Earth’s atmosphere: an Aerobee 150 first detected Scorpius X-1 (the first X-ray source detected in [...]

AT Microscopii – Astrometry

According to SIMBAD AT Mic has year 2000 (J2000) equatorial coordinates right ascension (RA) declination (Dec) due to Earth orbit precession from AT Mic at J1950 RA Dec . It has a stellar parallax in milliarcseconds (mas) of 97.80, or 10.22 parsecs (33.33 ly). Adapted from the Wikipedia article AT Microscopii, under the G. N. [...]

Extrasolar X-ray source astrometry – Counterparts

Astrometry

X‐ray source counterparts to stars can be identified by calculating the angular separation between source centroids and position of the star. The maximum allowable separation is a compromise between a larger value to identify as many real matches as possible and a smaller value to minimize the probability of spurious matches. “An adopted matching criterion [...]

Binary star – Introduction

Stellar Astrophysics

binary star is a star system consisting of two stars orbiting around their common center of mass. The brighter star is called the primary and the other is its companion star, comes, or secondary. Research between the early 1800s and today suggests that many stars are part of either binary star systems or star systems [...]

Extrasolar X-ray source astrometry – Astrometry for satellites

Astrometry

When satellite launching technology became available, satellites greatly increased the number of first X-ray sources in constellations: OSO 3 – Canis Minor X-1, Vela 5B – Camelopardalis X-1, Uhuru – Hercules X-1, and Einstein – Corona Australis X-1. For example, although Scutum X-1 was initially discovered with an X-ray payload on a sounding rocket in [...]

Extrasolar X-ray source astrometry – Ara X-1

Astrometry

Ara XR-1 was first observed on April 25, 1965, by an Aerobee 150 rocket at RA Dec , later by Uhuru (Uhuru catalog designation: 1U, 2U, 3U, and 4U) at 2U 1641-45, and 2U 1704-42. The Ariel catalogue places them at 2S 1642-455 and 2S 1702-429, but no visual counterpart has been found. It appears [...]

Astronomy – Introduction

Astronomy is a natural science that deals with the study of celestial objects (such as stars, planets, comets, nebulae, star clusters and galaxies) and phenomena that originate outside the Earth’s atmosphere (such as the cosmic background radiation). It is concerned with the evolution, physics, chemistry, meteorology, and motion of celestial objects, as well as the [...]









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