Systems that enable observing celestial bodies during daylight or in under cloudy conditions.

The subject matter disclosed herein is generally directed towards systems and methods for estimating vehicle attitude information using position data of stars and astronomical objects in the sky. Considerable advantages may be realized by equipping vehicles with low-cost star trackers adequate for filtering images based on statistical-based techniques, which could provide a robust and reliable attitude determination. The methods described herein provide algorithms to reduce the amount of processing capacity and memory for finding stars and astronomical objects. In some instances, the provided systems and methods allow the prediction of the next location of the stars and/or other astronomical objects to enhance the search by looking for them at the predicted location. The algorithms may be applied in real-time and are suitable for movable platforms with limited resources such as satellites and spacecraft.

A system and method include generating environment data from skylight sensor data. The environment data includes a value of a geospatially dependent parameter associated with light received from a predetermined celestial light source. At least two of a compass direction of the predetermined celestial light source when the skylight sensor data was received, a time at which the skylight sensor data was received, or a geospatial coordinate at which the skylight sensor data was collected are received. At least one of the compass direction of the predetermined celestial light source when the skylight sensor data was received, the time at which the skylight sensor data was received, or the geospatial coordinate at which the skylight sensor data was collected is determined, at least in part, from the environment data.

The invention discloses a method for correcting the pointing errors of a biaxial rotation system based on the spherical cap function, comprising: error collection: selecting stars or radio sources distributed evenly in a star catalogue for tracking and observation to obtain the theoretical position and measurement position of the stars, and subtracting the measurement positions and the theoretical positions to obtain the error distribution; error model fitting: selecting a suitable orthogonal spherical cap function for the obtained error distribution and performing fitting to calculate an error fitting coefficient, the orthogonal spherical cap function model comprising a hemispheric harmonic function HSH, a Zernike spherical cap function ZSF, and a longitudinal spherical cap function LSF; and error control and compensation: putting the error model and the related fitting coefficient into a pointing control system for compensation. In the present method for correcting the pointing errors of a biaxial rotation system based on a spherical cap function, the model has strong stability and is not easily affected by measurement noise; there is no need to determine the form of the model on the bases of the frame form of the telescope, and the correction accuracy is high.

A method of fully autonomous geometric calibration for linear-array remote sensing satellite (LARSS) based on the joint observation for stars and earth by satellite, with the support of satellite's high maneuverability is proposed. This invention realizes the full-link processing from data acquisition to internal and external calibration. Based on the ultra-high attitude stability and agile maneuverability, this invention designs a joint observation mode for the star and the earth, which is suitable for autonomous geometric calibration. With the joint observations, this invention achieves the external calibration through the star observations acquired in the solar shadow area, and achieves the internal calibration through the ground overlapping images acquired in the solar illumination area. Therefore, the high-precision geometric imaging model of the LARSS would be restored by the method, under the condition without using the ground calibration sites.

The present invention relates to a tracking device for tracking and observing or communicating with moving objects in space or in the atmosphere, wherein the present invention is devised to satisfy the aforementioned needs and an object of the present invention is to provide a tracking device of enabling a single mount to change a posture by one of an altitude-azimuth (ALT-AZ) control method, an equatorial control method, and an altitude-altitude (ALT-ALT) control method so as to facilitate the best tracking according to the operation characteristics of a moving object on the celestial sphere by variously controlling an installation angle of a main rotation shaft.

A stellar atmospheric refraction measurement correction method based on collinearity of refraction surfaces, comprising: performing star identification on the basis of observed star vectors in a star sensor and the reference star catalog, to obtain matching relationships between observed stars and reference stars; converting reference star vectors corresponding to the observed stars to a geographic coordinate system before entering the atmosphere to obtain zenith distances and azimuth angles of incident stellar; on the basis of a principle of collinearity of refraction surfaces, performing optimal solving according to imaging coordinates of observation stars, to obtain the optimal position coordinates of the zenith direction on an imaging surface of the star sensor; according to the optimal zenith direction, performing atmospheric refraction correction on all the recognized observed stars by means of the trigonometric cosine formula to obtain corrected star coordinates; and performing optimal solving to obtain the attitude of the star sensor in the geographic coordinate system.

A technique for polar aligning the mount of a telescope or other astronomical instrument includes acquiring star images from an electronic polar scope and determining a location of a celestial pole relative to the star images based on computerized matching of the star images to information in a database. The mount has a right-ascension (RA) axis, and the technique directs an adjustment to the mount so as to align a location of the RA axis with the determined location of the celestial pole.

System and method for determining a position of a target in an unbiased 3D measurement space: generating 2D measurement data in focal planes of each sensor; calculating a line of sight (LOS) from the target for each sensor; intersecting the LOSs and finding the closest intersection point in a 3D space; calculating a boresight LOS in 3D for each sensor; intersecting the boresight lines of sights for each sensor, and finding the closest intersection point in the 3D space to define an origin for forming the unbiased 3D measurement space; and forming local unbiased 3D estimates of the position of the target in the unbiased 3D measurement space as a difference between a closest point of the target LOS and a closest point of the boresight LOS.

Provided is a telescope star searching method and device based on image recognition and telescope. The method includes: using a telescope to photograph a starry sky image; identifying a star in the starry sky image and matching a right ascension and a declination of the identified star according to a star database; obtaining a first altitude/azimuth angle according to photographing time of the starry sky image, a location of an imaging apparatus at the photographing time, and the right ascension and the declination of the identified star; matching a right ascension and a declination of a target star in the star database; obtaining a second altitude/azimuth angle according to current time, a current location of the imaging apparatus, and the right ascension and the declination of the target star; and adjusting the telescope from the first altitude/azimuth angle to the second altitude/azimuth.